Added flicker-free planets to Commodore 64 version
This commit is contained in:
Mark Moxon
parent
3dc852da53
commit
47c4d5f029
4 changed files with 858 additions and 18 deletions
10
build.sh
10
build.sh
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@ -31,8 +31,8 @@ $c1541 \
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-write firebird \
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-write gma1.modified gma1 \
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-write gma3 \
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-write gma4 \
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-write gma5 \
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-write gma4.encrypted gma4 \
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-write gma5.encrypted gma5 \
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-write gma6.encrypted gma6
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# Report checksums
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@ -62,8 +62,8 @@ $c1541 \
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-write byebyejulie \
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-write gma1.modified gma1 \
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-write gma3 \
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-write gma4 \
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-write gma5 \
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-write gma4.encrypted gma4 \
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-write gma5.encrypted gma5 \
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-write gma6.encrypted gma6
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# Report checksums
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@ -77,7 +77,7 @@ cd work
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cp ../original-disks/elite_+4_unpacked.prg .
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# Assemble the additional code required for flicker-free ships
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$beebasm -i ../src/elite-flicker-free-plus4.asm -v > compile.txt
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$beebasm -i ../src/elite-flicker-free-plus4.asm -v >> compile.txt
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# Modify the main game code
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$python ../src/elite-modify-plus4.py
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@ -44,7 +44,6 @@ GUARD &CE00 \ Guard against assembling over memory used by game
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XX1 = $0009
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INWK = $0009
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XX19 = $002A
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CNT = $0030
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K3 = $0035
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K4 = $0043
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XX0 = $0057
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@ -56,6 +55,7 @@ X2 = $006D
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Y2 = $006E
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XX12 = $0071
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XX17 = $009F
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CNT = $00AA
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XX4 = $00AD
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XX20 = $00AE
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XX14 = $00FB
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@ -19,7 +19,7 @@
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\
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\ ******************************************************************************
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GUARD &CE00 \ Guard against assembling over memory used by game
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GUARD $CE00 \ Guard against assembling over memory used by game
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\ ******************************************************************************
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\
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@ -44,7 +44,6 @@ GUARD &CE00 \ Guard against assembling over memory used by game
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XX1 = $0009
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INWK = $0009
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XX19 = $002A
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CNT = $0030
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K3 = $0035
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K4 = $0043
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XX0 = $0057
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@ -56,6 +55,7 @@ X2 = $006D
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Y2 = $006E
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XX12 = $0071
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XX17 = $009F
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CNT = $00AA
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XX4 = $00AD
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XX20 = $00AE
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XX14 = $00FB
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@ -64,6 +64,26 @@ LL75 = $9FB8
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LL30 = $AB91
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Y = 72
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K = $0077
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LSP = $007E
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K5 = $0085
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K6 = $0089
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XX13 = $00A2
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TYPE = $00A5
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FLAG = $00A9
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CNT2 = $00AB
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STP = $00AC
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T = $00BB
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SWAP = $06F4
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LSX2 = $26A4
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LSY2 = $27A4
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PL9_2 = $7DA4
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PL26 = $7DE0
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PLL4 = $7E5F
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CIRCLE = $8044
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WP1 = $80F5
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LL145 = $A013
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\ ******************************************************************************
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\
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\ Name: SHPPT
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@ -263,7 +283,259 @@ ORG $A178
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SAVE "ll155.bin", LL155, P%
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ORG $CCE0
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\ ******************************************************************************
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\
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\ Name: BLINE
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\ Type: Subroutine
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\ Category: Drawing circles
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\ Summary: Draw a circle segment and add it to the ball line heap
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\
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\ ******************************************************************************
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ORG $2977
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GUARD $2A12
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.BLINE
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TXA \ Set K6(3 2) = (T X) + K4(1 0)
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ADC K4 \ = y-coord of centre + y-coord of new point
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STA K6+2 \
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LDA K4+1 \ so K6(3 2) now contains the y-coordinate of the new
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ADC T \ point on the circle but as a screen coordinate, to go
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STA K6+3 \ along with the screen y-coordinate in K6(1 0)
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LDA FLAG \ If FLAG = 0, jump down to BL1
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BEQ BL1
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INC FLAG \ Flag is &FF so this is the first call to BLINE, so
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\ increment FLAG to set it to 0, as then the next time
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\ we call BLINE it can draw the first line, from this
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\ point to the next
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.BL5
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JSR DrawPlanetLine \ Draw the current line from the old planet
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\ The following inserts a &FF marker into the LSY2 line
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\ heap to indicate that the next call to BLINE should
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\ store both the (X1, Y1) and (X2, Y2) points. We do
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\ this on the very first call to BLINE (when FLAG is
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\ &FF), and on subsequent calls if the segment does not
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\ fit on-screen, in which case we don't draw or store
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\ that segment, and we start a new segment with the next
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\ call to BLINE that does fit on-screen
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LDY LSP \ If byte LSP-1 of LSY2 = &FF, jump to BL7 to tidy up
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LDA #&FF \ and return from the subroutine, as the point that has
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CMP LSY2-1,Y \ been passed to BLINE is the start of a segment, so all
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BEQ BL7 \ we need to do is save the coordinate in K5, without
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\ moving the pointer in LSP
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STA LSY2,Y \ Otherwise we just tried to plot a segment but it
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\ didn't fit on-screen, so put the &FF marker into the
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\ heap for this point, so the next call to BLINE starts
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\ a new segment
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INC LSP \ Increment LSP to point to the next point in the heap
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BNE BL7 \ Jump to BL7 to tidy up and return from the subroutine
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\ (this BNE is effectively a JMP, as LSP will never be
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\ zero)
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.BL1
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LDA K5 \ Set XX15 = K5 = x_lo of previous point
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STA XX15
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LDA K5+1 \ Set XX15+1 = K5+1 = x_hi of previous point
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STA XX15+1
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LDA K5+2 \ Set XX15+2 = K5+2 = y_lo of previous point
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STA XX15+2
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LDA K5+3 \ Set XX15+3 = K5+3 = y_hi of previous point
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STA XX15+3
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LDA K6 \ Set XX15+4 = x_lo of new point
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STA XX15+4
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LDA K6+1 \ Set XX15+5 = x_hi of new point
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STA XX15+5
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LDA K6+2 \ Set XX12 = y_lo of new point
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STA XX12
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LDA K6+3 \ Set XX12+1 = y_hi of new point
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STA XX12+1
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JSR LL145 \ Call LL145 to see if the new line segment needs to be
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\ clipped to fit on-screen, returning the clipped line's
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\ end-points in (X1, Y1) and (X2, Y2)
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BCS BL5 \ If the C flag is set then the line is not visible on
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\ screen anyway, so jump to BL5, to avoid drawing and
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\ storing this line
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LDA SWAP \ If SWAP = 0, then we didn't have to swap the line
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BEQ BL9 \ coordinates around during the clipping process, so
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\ jump to BL9 to skip the following swap
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LDA X1 \ Otherwise the coordinates were swapped by the call to
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LDY X2 \ LL145 above, so we swap (X1, Y1) and (X2, Y2) back
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STA X2 \ again
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STY X1
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LDA Y1
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LDY Y2
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STA Y2
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STY Y1
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.BL9
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LDY LSP \ Set Y = LSP
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LDA LSY2-1,Y \ If byte LSP-1 of LSY2 is not &FF, jump down to BL8
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CMP #&FF \ to skip the following (X1, Y1) code
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BNE BL8
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\ Byte LSP-1 of LSY2 is &FF, which indicates that we
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\ need to store (X1, Y1) in the heap
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JSR DrawPlanetLine \ Draw the current line from the old planet
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LDA X1 \ Store X1 in the LSP-th byte of LSX2
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STA LSX2,Y
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LDA Y1 \ Store Y1 in the LSP-th byte of LSY2
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STA LSY2,Y
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INY \ Increment Y to point to the next byte in LSX2/LSY2
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.BL8
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LDA #&FF \ Set bit 7 of K3+8 so we do not draw the current line
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STA K3+8 \ in the call to DrawPlanetLine, but store the
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\ coordinates so we we can check them below
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JSR DrawPlanetLine+4 \ Calculate the current line from the old heap, but do
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\ not draw it, but store the coordinates (X1, Y1) and
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\ (X2, Y2) in K3+4 to K3+7
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LDA X2 \ Store X2 in the LSP-th byte of LSX2
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STA LSX2,Y
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LDA Y2 \ Store Y2 in the LSP-th byte of LSX2
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STA LSY2,Y
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INY \ Increment Y to point to the next byte in LSX2/LSY2
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STY LSP \ Update LSP to point to the same as Y
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JSR DrawNewPlanetLine \ Draw a line from (X1, Y1) to (X2, Y2), but only if it
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\ is different to the old line in K3+4 to K3+7
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LDA XX13 \ If XX13 is non-zero, jump up to BL5 to add a &FF
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BNE BL5 \ marker to the end of the line heap. XX13 is non-zero
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\ after the call to the clipping routine LL145 above if
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\ the end of the line was clipped, meaning the next line
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\ sent to BLINE can't join onto the end but has to start
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\ a new segment, and that's what inserting the &FF
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\ marker does
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.BL7
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LDA K6 \ Copy the data for this step point from K6(3 2 1 0)
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STA K5 \ into K5(3 2 1 0), for use in the next call to BLINE:
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LDA K6+1 \
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STA K5+1 \ * K5(1 0) = screen x-coordinate of this point
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\LDA K6+2 \
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\STA K5+2 \ * K5(3 2) = screen y-coordinate of this point
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\LDA K6+3 \
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\STA K5+3 \ They now become the "previous point" in the next call
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JMP PATCH3 \ Jump to patch to implement the commented out
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\ instructions above, plus the rest of the routine
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SAVE "bline.bin", BLINE, P%
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\ ******************************************************************************
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\
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\ Name: PL9 (Part 1 of 3)
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\ Type: Subroutine
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\ Category: Drawing planets
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\ Summary: Draw the planet, with either an equator and meridian, or a crater
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\
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\ ******************************************************************************
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ORG $7D8C
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GUARD $7DA4
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.PL9
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JSR CIRCLE \ Call CIRCLE to draw the planet's new circle
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BCS PL20A \ If the call to CIRCLE returned with the C flag set,
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\ then the circle does not fit on-screen, so jump to
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\ PL20A to remove the planet from the screen and return
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\ from the subroutine
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LDA K+1 \ If K+1 is zero, jump to PL25 as K(1 0) < 256, so the
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BEQ PL25 \ planet fits on the screen and we can draw meridians or
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\ craters
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.PL20
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JMP EraseRestOfPlanet \ We have drawn the new circle, so now we need to erase
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\ any lines that are left in the ball line heap, before
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\ returning from the subroutine using a tail call
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.PL20A
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JMP WPLS2 \ Call WPLS2 to remove the planet from the screen
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.PL25
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LDA $1D0F \ Skip craters and meridians if not configured
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BEQ PL20
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JMP PATCH6 \ Jump to PATCH6 for the rest of the routine
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SAVE "pl9.bin", PL9, P%
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\ ******************************************************************************
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\
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\ Name: WPLS2
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\ Type: Subroutine
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\ Category: Drawing planets
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\ Summary: Remove the planet from the screen
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\
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\ ******************************************************************************
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ORG $80BB
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GUARD $80F5
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.WPLS2
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LDY LSX2 \ If LSX2 is non-zero (which indicates the ball line
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BNE WP1 \ heap is empty), jump to WP1 to reset the line heap
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\ without redrawing the planet
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STY XX14 \ Reset XX14 to the start of the ball line heap (we can
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\ set this to 0 rather than 1 to take advantage of the
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\ fact that Y is 0 - the effect is the same)
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LDA LSP \ Set XX14+1 to the end of the ball line heap
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STA XX14+1
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JSR EraseRestOfPlanet \ Draw the contents of the ball line heap to erase the
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\ old planet
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JMP WP1 \ Reset the ball line heap and return from the
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\ subroutine using a tail call
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SAVE "wpls2.bin", WPLS2, P%
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\ ******************************************************************************
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\
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@ -274,6 +546,8 @@ ORG $CCE0
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\
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\ ******************************************************************************
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ORG $CCE0
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.LLX30
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LDY XX14 \ Set Y = XX14, to get the offset within the ship line
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@ -423,6 +697,319 @@ ORG $CCE0
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JMP LL78 \ Jump down to part 11
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\ ******************************************************************************
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\
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\ Name: EraseRestOfPlanet
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\ Type: Subroutine
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\ Category: Drawing lines
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\ Summary: Draw all remaining lines in the ball line heap to erase the rest
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\ of the old planet
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\
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\ ******************************************************************************
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.EraseRestOfPlanet
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LDY XX14 \ Set Y to the offset in XX14, which points to the part
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\ of the heap that we are overwriting with new points
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CPY XX14+1 \ If XX14 >= XX14+1, then we have already redrawn all of
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BCS eras1 \ the lines from the old circle's ball line heap, so
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\ skip the following
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JSR DrawPlanetLine \ Erase the next planet line from the ball line heap
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JMP EraseRestOfPlanet \ Loop back for the next line in the ball line heap
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.eras1
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RTS \ Return from the subroutine
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\ ******************************************************************************
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\
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\ Name: DrawPlanetLine
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\ Type: Subroutine
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\ Category: Drawing lines
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\ Summary: Draw a segment of the old planet from the ball line heap
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\
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\ ------------------------------------------------------------------------------
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\
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\ Other entry points:
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\
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\ DrawPlanetLine+4 If bit 7 of K3+8 is set, store the line coordinates in
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\ K3+4 to K3+7 (X1, Y1, X2, Y2) and do not draw the line
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\
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\ ******************************************************************************
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.DrawPlanetLine
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LDA #0 \ Clear bit 7 of K3+8 so we draw the current line below
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STA K3+8
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LDA #0 \ Clear bit 7 of K3+9 to indicate that there is no line
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STA K3+9 \ to draw (we may change this below)
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LDA XX14 \ If XX14 = 1, then this is the first point from the
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CMP #2 \ heap, so jump to plin3 to set the previous coordinate
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BCC plin3 \ and return from the subroutine
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LDA X1 \ Save X1, X2, Y1, Y2 and Y on the stack
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PHA
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LDA Y1
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PHA
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LDA X2
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PHA
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LDA Y2
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PHA
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TYA
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PHA
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LDY XX14 \ Set Y to the offset in XX14, which points to the part
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\ of the heap that we are overwriting with new points
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CPY XX14+1 \ If XX14 >= XX14+1, then we have already redrawn all of
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BCS plin1 \ the lines from the old circle's ball line heap, so
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\ jump to plin1 to return from the subroutine
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\ Otherwise we need to draw the line from the heap, to
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\ erase it from the screen
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LDA K3+2 \ Set X1 = K3+2 = screen x-coordinate of previous point
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STA X1 \ from the old heap
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LDA K3+3 \ Set Y1 = K3+3 = screen y-coordinate of previous point
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STA Y1 \ from the old heap
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LDA LSX2,Y \ Set X2 to the y-coordinate from the XX14-th point in
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STA X2 \ the heap
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STA K3+2 \ Store the x-coordinate of the point we are overwriting
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\ in K3+2, so we can use it on the next iteration
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LDA LSY2,Y \ Set Y2 to the y-coordinate from the XX14-th point in
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STA Y2 \ the heap
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STA K3+3 \ Store the y-coordinate of the point we are overwriting
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\ in K3+3, so we can use it on the next iteration
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INC XX14 \ Increment XX14 to point to the next coordinate, so we
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\ work our way through the current heap
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LDA Y1 \ If Y1 or Y2 = &FF then this indicates a break in the
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CMP #&FF \ circle, so jump to plin1 to skip the following and
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BEQ plin1 \ return from the subroutine, asthere is no line to
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LDA Y2 \ erase
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CMP #&FF
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BEQ plin1
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DEC K3+9 \ Decrement K3+9 to &FF to indicate that there is a line
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\ to draw
|
||||
|
||||
BIT K3+8 \ If bit 7 of K3+8 is set, jump to plin2 to store the
|
||||
BMI plin2 \ line coordinates rather than drawing the line
|
||||
|
||||
JSR LL30 \ The coordinates in (X1, Y1) and (X2, Y2) that we just
|
||||
\ pulled from the ball line heap point to a line that is
|
||||
\ still on-screen, so call LL30 to draw this line and
|
||||
\ erase it from the screen
|
||||
|
||||
.plin1
|
||||
|
||||
PLA \ Restore Y, X1, X2, Y1 and Y2 from the stack
|
||||
TAY
|
||||
PLA
|
||||
STA Y2
|
||||
PLA
|
||||
STA X2
|
||||
PLA
|
||||
STA Y1
|
||||
PLA
|
||||
STA X1
|
||||
|
||||
RTS \ Return from the subroutine
|
||||
|
||||
.plin2
|
||||
|
||||
LDA X1 \ Store X1, Y1, X2, Y2 in K3+4 to K3+7
|
||||
STA K3+4
|
||||
LDA Y1
|
||||
STA K3+5
|
||||
LDA X2
|
||||
STA K3+6
|
||||
LDA Y2
|
||||
STA K3+7
|
||||
|
||||
JMP plin1 \ Jump to plin1 to return from the subroutine
|
||||
|
||||
.plin3
|
||||
|
||||
LDA LSX2+1 \ Store the heap's first coordinate in K3+2 and K3+3
|
||||
STA K3+2
|
||||
LDA LSY2+1
|
||||
STA K3+3
|
||||
|
||||
INC XX14 \ Increment XX14 to point to the next coordinate, so we
|
||||
\ work our way through the current heap
|
||||
|
||||
RTS \ Return from the subroutine
|
||||
|
||||
\ ******************************************************************************
|
||||
\
|
||||
\ Name: DrawNewPlanetLine
|
||||
\ Type: Subroutine
|
||||
\ Category: Drawing lines
|
||||
\ Summary: Draw a ball line, but only if it is different to the old line
|
||||
\
|
||||
\ ------------------------------------------------------------------------------
|
||||
\
|
||||
\ Arguments:
|
||||
\
|
||||
\ K3+4 to K3+7 The (X1, Y1) and (X2, Y2) coordinates of the old line
|
||||
\
|
||||
\ ******************************************************************************
|
||||
|
||||
.DrawNewPlanetLine
|
||||
|
||||
BIT K3+9 \ If bit 7 of K3+9 is clear, then there is no old line
|
||||
BPL nlin2 \ to draw, so jump to nlin2 to draw the new line only
|
||||
|
||||
LDA K3+4 \ If the old line equals the new line, jump to nlin3
|
||||
CMP X1 \ to skip drawing both lines
|
||||
BNE nlin1
|
||||
LDA K3+5
|
||||
CMP Y1
|
||||
BNE nlin1
|
||||
LDA K3+6
|
||||
CMP X2
|
||||
BNE nlin1
|
||||
LDA K3+7
|
||||
CMP Y2
|
||||
BEQ nlin3
|
||||
|
||||
.nlin1
|
||||
|
||||
\ If we get here then the old line is differnt to the new
|
||||
\ line, so we draw them both
|
||||
|
||||
JSR LL30 \ Draw the new line from (X1, Y1) to (X2, Y2)
|
||||
|
||||
LDA K3+4 \ Set up the old line's coordinates
|
||||
STA X1
|
||||
LDA K3+5
|
||||
STA Y1
|
||||
LDA K3+6
|
||||
STA X2
|
||||
LDA K3+7
|
||||
STA Y2
|
||||
|
||||
.nlin2
|
||||
|
||||
JSR LL30 \ Draw the old line to erase it
|
||||
|
||||
.nlin3
|
||||
|
||||
RTS \ Return from the subroutine
|
||||
|
||||
SAVE "extra.bin", LLX30, P%
|
||||
|
||||
\ ******************************************************************************
|
||||
\
|
||||
\ Name: BLINE
|
||||
\ Type: Subroutine
|
||||
\ Category: Drawing circles
|
||||
\ Summary: Draw a circle segment and add it to the ball line heap
|
||||
\
|
||||
\ ******************************************************************************
|
||||
|
||||
ORG $69C0
|
||||
|
||||
GUARD $6A00 \ Guard against assembling over memory used by game
|
||||
|
||||
.PATCH3
|
||||
|
||||
\ These are the instructions from the end of BLINE that
|
||||
\ we move here so there's room for the patch
|
||||
|
||||
LDA K6+2 \
|
||||
STA K5+2 \ * K5(3 2) = screen y-coordinate of this point
|
||||
LDA K6+3 \
|
||||
STA K5+3 \ They now become the "previous point" in the next call
|
||||
|
||||
LDA CNT \ Set CNT = CNT + STP
|
||||
CLC
|
||||
ADC STP
|
||||
STA CNT
|
||||
|
||||
RTS \ Return from the subroutine
|
||||
|
||||
\ ******************************************************************************
|
||||
\
|
||||
\ Name: PLS22
|
||||
\ Type: Subroutine
|
||||
\ Category: Drawing planets
|
||||
\ Summary: Draw an ellipse or half-ellipse
|
||||
\
|
||||
\ ******************************************************************************
|
||||
|
||||
.PATCH4
|
||||
|
||||
\ We replace the following instruction just before PL40
|
||||
\ in PLS22 with JMP PATCH4, so we now do this
|
||||
\ instruction to ensure that it still gets done
|
||||
|
||||
STA CNT2 \ Set CNT2 = (CNT2 + STP) mod 64
|
||||
|
||||
JMP PLL4 \ Jump back to PLL4 to draw the next segment
|
||||
|
||||
\ ******************************************************************************
|
||||
\
|
||||
\ Name: CIRCLE2
|
||||
\ Type: Subroutine
|
||||
\ Category: Drawing circles
|
||||
\ Summary: Draw a circle (for the planet or chart)
|
||||
\ Deep dive: Drawing circles
|
||||
\
|
||||
\ ******************************************************************************
|
||||
|
||||
.PATCH5
|
||||
|
||||
LDX #0 \ Set XX14 = 0, to point to the offset before the first
|
||||
STX XX14 \ set of circle coordinates in the ball line heap
|
||||
|
||||
LDX LSP \ Set XX14+1 to the last byte of the ball line heap
|
||||
STX XX14+1
|
||||
|
||||
LDX #1 \ Set LSP = 1 to reset the ball line heap pointer
|
||||
STX LSP
|
||||
|
||||
\ We replace the following instructions at CIRCLE2 with
|
||||
\ JSR PATCH5, so we now do those two instructions to
|
||||
\ ensure that they still get done
|
||||
|
||||
LDX #&FF \ Set FLAG = &FF to reset the ball line heap in the call
|
||||
STX FLAG \ to the BLINE routine below
|
||||
|
||||
RTS \ Return from the subroutine
|
||||
|
||||
\ ******************************************************************************
|
||||
\
|
||||
\ Name: PL9 (Part 1 of 3)
|
||||
\ Type: Subroutine
|
||||
\ Category: Drawing planets
|
||||
\ Summary: Draw the planet, with either an equator and meridian, or a crater
|
||||
\
|
||||
\ ******************************************************************************
|
||||
|
||||
.PATCH6
|
||||
|
||||
LDA TYPE \ If the planet type is 128 then it has an equator and
|
||||
CMP #128 \ a meridian, so this jumps to PL26 if this is not a
|
||||
BNE P%+5 \ planet with an equator - in other words, if it is a
|
||||
\ planet with a crater
|
||||
|
||||
JMP PL9_2 \ Otherwise this is a planet with an equator and
|
||||
\ meridian, so jump to the equator routine in part 2 of
|
||||
\ PL9
|
||||
|
||||
JMP PL26 \ Jump to the crater routine
|
||||
|
||||
SAVE "extra2.bin", PATCH3, P%
|
||||
|
|
|
|||
|
|
@ -14,8 +14,17 @@
|
|||
# It does the following:
|
||||
#
|
||||
# * Decrypt the gma6 file
|
||||
# * Modify the gma6 file to draw flicker-free ships
|
||||
# * Modify the gma6 file to draw flicker-free ships and planets
|
||||
# * Encrypt the gma6 file
|
||||
#
|
||||
# * Decrypt the gma5 file
|
||||
# * Modify the gma5 file to draw flicker-free planets
|
||||
# * Encrypt the gma5 file
|
||||
#
|
||||
# * Decrypt the gma4 file
|
||||
# * Modify the gma4 file to draw flicker-free planets
|
||||
# * Encrypt the gma4 file
|
||||
#
|
||||
# * Modify the gma1 file to remove disk protection
|
||||
#
|
||||
# Run this script by changing directory to the folder containing the disk files
|
||||
|
|
@ -86,7 +95,7 @@ print()
|
|||
print("Modifying Commodore 64 Elite")
|
||||
print("Platform: {}".format(platform.upper()))
|
||||
|
||||
# Configuration variables
|
||||
# Configuration variables for gma6
|
||||
|
||||
load_address = 0x6A00 - 2
|
||||
seed = 0x49
|
||||
|
|
@ -288,9 +297,9 @@ insert_nops(data_block, 0x9FC1, 1)
|
|||
# NOP
|
||||
|
||||
insert_bytes(data_block, 0x9FD9, [
|
||||
0xC8, # INY
|
||||
0xB1, 0x5B, # LDA (V),Y
|
||||
0xAA # TAX
|
||||
0xC8, # INY
|
||||
0xB1, 0x5B, # LDA (V),Y
|
||||
0xAA # TAX
|
||||
])
|
||||
|
||||
lda_sta_block = get_offset(0x9FDD)
|
||||
|
|
@ -298,9 +307,9 @@ for n in range(lda_sta_block, lda_sta_block + 4 * 5):
|
|||
data_block[n] = data_block[n + 4]
|
||||
|
||||
insert_bytes(data_block, 0x9FF1, [
|
||||
0xC8, # INY
|
||||
0xB1, 0x5B, # LDA (V),Y
|
||||
0xAA # TAX
|
||||
0xC8, # INY
|
||||
0xB1, 0x5B, # LDA (V),Y
|
||||
0xAA # TAX
|
||||
])
|
||||
insert_nops(data_block, 0x9FF5, 2)
|
||||
|
||||
|
|
@ -316,7 +325,7 @@ insert_nops(data_block, 0x9FF5, 2)
|
|||
# To: JMP PATCH2
|
||||
|
||||
insert_bytes(data_block, 0xA010, [
|
||||
0x4C, patch2 % 256, patch2 // 256 # JMP PATCH2
|
||||
0x4C, patch2 % 256, patch2 // 256 # JMP PATCH2
|
||||
])
|
||||
|
||||
# LL9 (Part 11)
|
||||
|
|
@ -359,6 +368,91 @@ elite_file.close()
|
|||
|
||||
print("[ Modify ] append file extra.bin")
|
||||
|
||||
# We now move on to the routines for drawing flicker-free planets
|
||||
|
||||
# Set the addresses for the extra routines (LLX30, PATCH1, PATCH2) that we will
|
||||
# append to the end of the main game code (where there is a bit of free space)
|
||||
|
||||
erasep = 0xCD3B
|
||||
patch4 = 0x69D0
|
||||
patch5 = 0x69D5
|
||||
|
||||
# PL9 (Part 1 of 3)
|
||||
#
|
||||
# We have already assembled the modified part 1 of PL9 in BeebAsm and saved
|
||||
# it as the binary file pl9.bin, so now we drop this over the top of the
|
||||
# existing routine (the new routine is slightly bigger, so it ends by jumping
|
||||
# to PATCH6, which contains the spill-over).
|
||||
|
||||
insert_binary_file(data_block, 0x7D8C, "pl9.bin")
|
||||
|
||||
# PL9 (Part 2 of 3)
|
||||
#
|
||||
# The above modification moves PL20, so we need to modify the branch instruction
|
||||
# at the start of part 2 of PL9.
|
||||
|
||||
insert_bytes(data_block, 0x7DA8, [
|
||||
0x90, 0xEB # BCC PL20
|
||||
])
|
||||
|
||||
# PL9 (Part 3 of 3)
|
||||
#
|
||||
# The above modification moves PL20, so we need to modify the branch instruction
|
||||
# at the start of part 3 of PL9.
|
||||
|
||||
insert_bytes(data_block, 0x7DE2, [
|
||||
0x30, 0xB1 # BMI PL20
|
||||
])
|
||||
|
||||
# WPLS2
|
||||
#
|
||||
# We have already assembled the modified part 1 of PL9 in BeebAsm and saved
|
||||
# it as the binary file pl9.bin, so now we drop this over the top of the
|
||||
# existing routine (which is quite a bit longer, so there is room).
|
||||
|
||||
insert_binary_file(data_block, 0x80BB, "wpls2.bin")
|
||||
|
||||
# PLS22
|
||||
#
|
||||
# This is the modification on either side of PL40, with the label moving two
|
||||
# bytes backwards to accommodate the modified code.
|
||||
#
|
||||
# From: BCS PL40
|
||||
# ...
|
||||
# STA CNT2
|
||||
# JMP PLL4
|
||||
# .PL40
|
||||
# RTS
|
||||
#
|
||||
# To: BCS PL40
|
||||
# ...
|
||||
# JMP PATCH4
|
||||
# .PL40
|
||||
# JMP EraseRestOfPlanet
|
||||
|
||||
insert_bytes(data_block, 0x7F04, [
|
||||
0xB0, 0x0A # BCS PL40
|
||||
])
|
||||
insert_bytes(data_block, 0x7F0D, [
|
||||
0x4C, patch4 % 256, patch4 // 256, # JMP PATCH4
|
||||
0x4C, erasep % 256, erasep // 256 # JMP EraseRestOfPlanet
|
||||
])
|
||||
|
||||
# CIRCLE2
|
||||
#
|
||||
# This is the modification at the start of the routine.
|
||||
#
|
||||
# From: LDX #&FF
|
||||
# STX FLAG
|
||||
#
|
||||
# To: JSR PATCH5
|
||||
# NOP
|
||||
|
||||
insert_bytes(data_block, 0x805E, [
|
||||
0x20, patch5 % 256, patch5 // 256 # JSR PATCH5
|
||||
])
|
||||
insert_nops(data_block, 0x8061, 1)
|
||||
|
||||
# All the modifications are done, so write the output file for gma6.modified,
|
||||
# which we can use for debugging
|
||||
|
||||
|
|
@ -386,6 +480,165 @@ output_file.close()
|
|||
|
||||
print("[ Save ] gma6.encrypted")
|
||||
|
||||
# Configuration variables for gma5
|
||||
|
||||
load_address = 0x1D00 - 2
|
||||
seed = 0x36
|
||||
scramble_from = 0x1D00
|
||||
scramble_to = 0x1D00 + (0x21D4 - 3) # File size - 3
|
||||
|
||||
# Set up an array to hold the gma5 binary, so we can modify it
|
||||
|
||||
data_block = bytearray()
|
||||
|
||||
# Load the gma5 code file into data_block
|
||||
|
||||
elite_file = open("gma5", "rb")
|
||||
data_block.extend(elite_file.read())
|
||||
elite_file.close()
|
||||
|
||||
print()
|
||||
print("[ Read ] gma5")
|
||||
|
||||
# Decrypt the gma5 code file
|
||||
|
||||
updated_seed = seed
|
||||
|
||||
for n in range(scramble_to, scramble_from - 1, -1):
|
||||
new = (data_block[n - load_address] - updated_seed) % 256
|
||||
data_block[n - load_address] = new
|
||||
updated_seed = new
|
||||
|
||||
print("[ Decrypt ] gma5")
|
||||
|
||||
# Write an output file containing the decrypted but unmodified gma5 code, which
|
||||
# we can use for debugging
|
||||
|
||||
output_file = open("gma5.decrypted", "wb")
|
||||
output_file.write(data_block)
|
||||
output_file.close()
|
||||
|
||||
print("[ Save ] gma5.decrypted")
|
||||
|
||||
# BLINE
|
||||
#
|
||||
# We have already assembled the modified BLINE in BeebAsm and saved it as the
|
||||
# binary file bline.bin, so now we drop this over the top of the existing
|
||||
# routine (the new routine is slightly bigger, so it ends by jumping to PATCH3,
|
||||
# which contains the spill-over).
|
||||
|
||||
insert_binary_file(data_block, 0x2977, "bline.bin")
|
||||
|
||||
# All the modifications are done, so write the output file for gma5.modified,
|
||||
# which we can use for debugging
|
||||
|
||||
output_file = open("gma5.modified", "wb")
|
||||
output_file.write(data_block)
|
||||
output_file.close()
|
||||
|
||||
print("[ Save ] gma5.modified")
|
||||
|
||||
# Encrypt the gma5 code file
|
||||
|
||||
for n in range(scramble_from, scramble_to):
|
||||
data_block[n - load_address] = (data_block[n - load_address] + data_block[n + 1 - load_address]) % 256
|
||||
|
||||
data_block[scramble_to - load_address] = (data_block[scramble_to - load_address] + seed) % 256
|
||||
|
||||
print("[ Encrypt ] gma5.modified")
|
||||
|
||||
# Write the output file for gma5.encrypted, which contains our modified game
|
||||
# binary with the flicker-free code
|
||||
|
||||
output_file = open("gma5.encrypted", "wb")
|
||||
output_file.write(data_block)
|
||||
output_file.close()
|
||||
|
||||
print("[ Save ] gma5.encrypted")
|
||||
|
||||
# Configuration variables for gma4
|
||||
|
||||
load_address = 0x4000 - 2
|
||||
seed = 0x8E
|
||||
scramble_from = 0x75E4
|
||||
scramble_to = 0x865A
|
||||
|
||||
# Set up an array to hold the gma4 binary, so we can modify it
|
||||
|
||||
data_block = bytearray()
|
||||
|
||||
# Load the gma4 code file into data_block
|
||||
|
||||
elite_file = open("gma4", "rb")
|
||||
data_block.extend(elite_file.read())
|
||||
elite_file.close()
|
||||
|
||||
print()
|
||||
print("[ Read ] gma4")
|
||||
|
||||
# Decrypt the gma4 code file
|
||||
|
||||
updated_seed = seed
|
||||
|
||||
for n in range(scramble_to, scramble_from - 1, -1):
|
||||
new = (data_block[n - load_address] - updated_seed) % 256
|
||||
data_block[n - load_address] = new
|
||||
updated_seed = new
|
||||
|
||||
print("[ Decrypt ] gma4")
|
||||
|
||||
# Write an output file containing the decrypted but unmodified gma4 code, which
|
||||
# we can use for debugging
|
||||
|
||||
output_file = open("gma4.decrypted", "wb")
|
||||
output_file.write(data_block)
|
||||
output_file.close()
|
||||
|
||||
print("[ Save ] gma4.decrypted")
|
||||
|
||||
# We now insert the four extra routines required by the modifications into
|
||||
# the unused space just after the sprites:
|
||||
#
|
||||
# PATCH3
|
||||
# PATCH4
|
||||
# PATCH5
|
||||
# PATCH6
|
||||
#
|
||||
# We have already assembled these in BeebAsm and saved them as the binary file
|
||||
# extra2.bin, so we simply insert this file at the correct address. The contents
|
||||
# of the GMA4 file is moved after decryption, so although the routines end up at
|
||||
# $69C0, they actually get loaded and decrypted at $7C3A, so that's the address
|
||||
# we use when inserting the code into the gm4 file:
|
||||
|
||||
insert_binary_file(data_block, 0x7C3A, "extra2.bin")
|
||||
|
||||
# All the modifications are done, so write the output file for gma4.modified,
|
||||
# which we can use for debugging
|
||||
|
||||
output_file = open("gma4.modified", "wb")
|
||||
output_file.write(data_block)
|
||||
output_file.close()
|
||||
|
||||
print("[ Save ] gma4.modified")
|
||||
|
||||
# Encrypt the gma4 code file
|
||||
|
||||
for n in range(scramble_from, scramble_to):
|
||||
data_block[n - load_address] = (data_block[n - load_address] + data_block[n + 1 - load_address]) % 256
|
||||
|
||||
data_block[scramble_to - load_address] = (data_block[scramble_to - load_address] + seed) % 256
|
||||
|
||||
print("[ Encrypt ] gma4.modified")
|
||||
|
||||
# Write the output file for gma4.encrypted, which contains our modified game
|
||||
# binary with the flicker-free code
|
||||
|
||||
output_file = open("gma4.encrypted", "wb")
|
||||
output_file.write(data_block)
|
||||
output_file.close()
|
||||
|
||||
print("[ Save ] gma4.encrypted")
|
||||
|
||||
# Finally, we need to remove the disk protection from gma1, as described here:
|
||||
# https://www.lemon64.com/forum/viewtopic.php?t=67762&start=90
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue