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Move code out of sight sprites and into the NOP part of the Trumble routine

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This commit is contained in:
Mark Moxon 2023-02-28 12:46:57 +00:00
commit 19f7dbf8aa
2 changed files with 127 additions and 91 deletions
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177
src/elite-flicker-free-plus4.asm
View file

@ -535,6 +535,81 @@ GUARD $80F5 + $08F0
JMP WP1 \ Reset the ball line heap and return from the JMP WP1 \ Reset the ball line heap and return from the
\ subroutine using a tail call \ subroutine using a tail call
\ ******************************************************************************
\
\ Name: EraseRestOfPlanet
\ Type: Subroutine
\ Category: Drawing lines
\ Summary: Draw all remaining lines in the ball line heap to erase the rest
\ of the old planet
\
\ ******************************************************************************
.EraseRestOfPlanet
LDY XX14 \ Set Y to the offset in XX14, which points to the part
\ of the heap that we are overwriting with new points
CPY XX14+1 \ If XX14 >= XX14+1, then we have already redrawn all of
BCS eras1 \ the lines from the old circle's ball line heap, so
\ skip the following
JSR DrawPlanetLine \ Erase the next planet line from the ball line heap
JMP EraseRestOfPlanet \ Loop back for the next line in the ball line heap
.eras1
RTS \ Return from the subroutine
\ ******************************************************************************
\
\ Name: BLINE
\ Type: Subroutine
\ Category: Drawing circles
\ Summary: Draw a circle segment and add it to the ball line heap
\
\ ******************************************************************************
.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: 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 "wpls2-plus4.bin", WPLS2, P% SAVE "wpls2-plus4.bin", WPLS2, P%
\ ****************************************************************************** \ ******************************************************************************
@ -546,7 +621,7 @@ SAVE "wpls2-plus4.bin", WPLS2, P%
\ \
\ ****************************************************************************** \ ******************************************************************************
ORG $7100 ORG $7200
GUARD $7300 GUARD $7300
@ -699,33 +774,6 @@ GUARD $7300
JMP LL78 \ Jump down to part 11 JMP LL78 \ Jump down to part 11
\ ******************************************************************************
\
\ Name: EraseRestOfPlanet
\ Type: Subroutine
\ Category: Drawing lines
\ Summary: Draw all remaining lines in the ball line heap to erase the rest
\ of the old planet
\
\ ******************************************************************************
.EraseRestOfPlanet
LDY XX14 \ Set Y to the offset in XX14, which points to the part
\ of the heap that we are overwriting with new points
CPY XX14+1 \ If XX14 >= XX14+1, then we have already redrawn all of
BCS eras1 \ the lines from the old circle's ball line heap, so
\ skip the following
JSR DrawPlanetLine \ Erase the next planet line from the ball line heap
JMP EraseRestOfPlanet \ Loop back for the next line in the ball line heap
.eras1
RTS \ Return from the subroutine
\ ****************************************************************************** \ ******************************************************************************
\ \
\ Name: DrawPlanetLine \ Name: DrawPlanetLine
@ -854,6 +902,28 @@ GUARD $7300
RTS \ Return from the subroutine RTS \ Return from the subroutine
SAVE "extra-plus4.bin", LLX30, P%
\ ******************************************************************************
\
\ Name: Put patches into NOPs in Trumble code
\ Type: Subroutine
\
\ ******************************************************************************
ORG $1E6A
GUARD $1EB6
.TRUMBLE
JMP PATCHEND \ We inject the following into the batch of NOPs that
\ the Plus/4 version has inserted into the middle of the
\ Trumble sprite-plotting routine, so this instruction
\ just skips over the patches so the routine can still
\ run (the Trumble routine does not have an entry point
\ within the NOPs, so this is safe)
\ ****************************************************************************** \ ******************************************************************************
\ \
\ Name: DrawNewPlanetLine \ Name: DrawNewPlanetLine
@ -911,32 +981,6 @@ GUARD $7300
RTS \ Return from the subroutine RTS \ Return from the subroutine
\ ******************************************************************************
\
\ Name: BLINE
\ Type: Subroutine
\ Category: Drawing circles
\ Summary: Draw a circle segment and add it to the ball line heap
\
\ ******************************************************************************
.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 \ Name: PLS22
@ -986,27 +1030,6 @@ GUARD $7300
RTS \ Return from the subroutine RTS \ Return from the subroutine
\ ****************************************************************************** .PATCHEND
\
\ 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 "extra-plus4.bin", LLX30, P%
SAVE "trumble-plus4.bin", TRUMBLE, P%

41
src/elite-modify-plus4.py
View file

@ -89,9 +89,9 @@ print("[ Read ] elite_+4_unpacked.prg")
# Set the addresses for the extra routines (LLX30, PATCH1, PATCH2) that we will # Set the addresses for the extra routines (LLX30, PATCH1, PATCH2) that we will
# load into unused portiong of the main game code # load into unused portiong of the main game code
llx30 = 0x7100 llx30 = 0x7200
patch1 = 0x713E patch1 = 0x723E
patch2 = 0x7155 patch2 = 0x7255
# We now modify the code to implement flicker-free ship drawing. The code # We now modify the code to implement flicker-free ship drawing. The code
# changes are described here, which can be read alongside the following: # changes are described here, which can be read alongside the following:
@ -304,27 +304,24 @@ insert_binary_file(data_block, 0xA15B + 0x900, "ll78-plus4.bin")
insert_binary_file(data_block, 0xA178 + 0x900, "ll155-plus4.bin") insert_binary_file(data_block, 0xA178 + 0x900, "ll155-plus4.bin")
# We now load the three extra routines required by the modifications into the # We now load the three extra routines required by the modifications into the
# memory used by the Trumble sprites, which are not used in the Plus/4 version: # memory used by the explosion and Trumble sprites, which are not used in the
# Plus/4 version:
# #
# LLX30 # LLX30
# PATCH1 # PATCH1
# PATCH2 # PATCH2
# # DrawPlanetLine
# PATCH3
# PATCH4
# PATCH5
# PATCH6
insert_binary_file(data_block, 0x7100, "extra-plus4.bin") insert_binary_file(data_block, 0x7200, "extra-plus4.bin")
# We now move on to the routines for drawing flicker-free planets # We now move on to the routines for drawing flicker-free planets
# Set the addresses for the extra routines (EraseRestOfPlanet, PATCH4, PATCH5) # Set the addresses for the extra routines (EraseRestOfPlanet, PATCH4, PATCH5)
# that we inserted above # that we inserted above
erasep = 0x715B erasep = 0x89BC
patch4 = 0x7229 patch4 = 0x1EA0
patch5 = 0x722E patch5 = 0x1EA5
# PL9 (Part 1 of 3) # PL9 (Part 1 of 3)
# #
@ -357,7 +354,12 @@ insert_bytes(data_block, 0x7DE2 + 0x8F0, [
# #
# We have already assembled the modified WPLS2 in BeebAsm and saved it as # We have already assembled the modified WPLS2 in BeebAsm and saved it as
# the binary file wpls2.bin, so now we drop this over the top of the # the binary file wpls2.bin, so now we drop this over the top of the
# existing routine (which is quite a bit longer, so there is room). # existing routine. This binary contains the following routines:
#
# WPLS2
# EraseRestOfPlanet
# PATCH3
# PATCH6
insert_binary_file(data_block, 0x80BB + 0x8F0, "wpls2-plus4.bin") insert_binary_file(data_block, 0x80BB + 0x8F0, "wpls2-plus4.bin")
@ -411,6 +413,17 @@ insert_nops(data_block, 0x8061 + 0x8F0, 1)
insert_binary_file(data_block, 0x2974, "bline-plus4.bin") insert_binary_file(data_block, 0x2974, "bline-plus4.bin")
# We now load the extra routines required by the modifications into the memory
# used by the Trumble sprite-drawing routine, which contains a whole raft of
# NOPs in the Plus/4 version. We can therefore slip the following routines into
# this set of NOPs, adding a JMP beforehand to skip over the patches:
#
# DrawNewPlanetLine
# PATCH4
# PATCH5
insert_binary_file(data_block, 0x1E6A, "trumble-plus4.bin")
# All the modifications are done, so write the output file for the modified PRG # All the modifications are done, so write the output file for the modified PRG
output_file = open("elite_+4_modified.prg", "wb") output_file = open("elite_+4_modified.prg", "wb")