Retro/c64-elite-flicker-free
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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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41
src/elite-modify-plus4.py
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@ -89,9 +89,9 @@ print("[ Read ] elite_+4_unpacked.prg")
# Set the addresses for the extra routines (LLX30, PATCH1, PATCH2) that we will
# load into unused portiong of the main game code
llx30 = 0x7100
patch1 = 0x713E
patch2 = 0x7155
llx30 = 0x7200
patch1 = 0x723E
patch2 = 0x7255
# We now modify the code to implement flicker-free ship drawing. The code
# 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")
# 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
# PATCH1
# PATCH2
#
# PATCH3
# PATCH4
# PATCH5
# PATCH6
# DrawPlanetLine
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
# Set the addresses for the extra routines (EraseRestOfPlanet, PATCH4, PATCH5)
# that we inserted above
erasep = 0x715B
patch4 = 0x7229
patch5 = 0x722E
erasep = 0x89BC
patch4 = 0x1EA0
patch5 = 0x1EA5
# 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
# 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")
@ -411,6 +413,17 @@ insert_nops(data_block, 0x8061 + 0x8F0, 1)
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
output_file = open("elite_+4_modified.prg", "wb")