ASM6f is a fork of ASM6, primarily targeted at NES/Famicom development.
Usage:
asm6f [-options] sourcefile [outputfile] [listfile]Options:
-? Show some help
-l Create listing
-L Create verbose listing (expand REPT, MACRO)
-d<name>: Define a symbol and make it equal to 1
-q Quiet mode (suppress all output unless there's an error)
-n export FCEUX-compatible .nl files
-f export Lua symbol file
-c export .cdl for use with FCEUX/Mesen
-m export new format Mesen label file (.mlb)
-M export old format Mesen label file (.mlb)
Default output is <sourcefile>.bin
Default listing is <sourcefile>.lstRight now, everything else is the same as the original ASM6, so check out readme-original.txt for more information.
asm6f supports the use of a number of undocumented/"illegal" opcodes. Unstable opcodes require the use of the "UNSTABLE" and/or "HUNSTABLE" directives, or an error will be thrown.
Information about these opcodes was sourced from Graham's 6502 Opcode document: http://www.oxyron.de/html/opcodes02.html
[Normal] These opcodes appear to be "safe" to use. The alternate $EB opcode for sbc #{immediate} is not supported.
slo (Shift Left, Or)
slo {addrmode} = asl {addrmode} + ora {addrmode}
Known as "aso" in other undocumented opcode sources.rla (Rol Left, And)
rla {addrmode} = rol {addrmode} + and {addrmode}sre (Shift Right, Exclusive or)
sre {addrmode} = lsr {addrmode} + eor {addrmode}
Known as "lse" in other undocumented opcode sources.rra (Ror Right, Add with carry)
rra {addrmode} = ror {addrmode} + adc {addrmode}sax (Store A&X)
sax {addrmode} = store A&X into {addrmode}
"The A&X operation is a result of A and X put onto the bus
at the same time."lax (Load A&X)
lax {addrmode} = lda {addrmode} + ldx {addrmode}dcp (Decrement, ComPare)
dcp {addrmode} = dec {addrmode} + cmp {addrmode}isc (Increment, Subtract with Carry)
isc {addrmode} = inc {addrmode} + sbc {addrmode}
Known as "isb" in other undocumented opcode sources.anc
anc #{immediate} = and #{immediate} + (asl)
"this command performs an AND operation only, but bit 7 is put into
the carry, as if the ASL/ROL would have been executed."alr (And Left Rotate)
alr #{immediate} = and #{immediate} + (rol)
Known as "asr" in other undocumented opcode sources.arr
arr #{immediate} = and #{immediate} + lsr
"Part of this command are some ADC mechanisms. Following effects appear
after AND but before ROR: the V-Flag is set according to (A and #{imm})+#{imm},
bit 0 does NOT go into carry, but bit 7 is exchanged with the carry."axs (A&X, Subtract immediate)
axs #{immediate} = A&X minus #{immediate} into X
Known as "sbx" in other undocumented opcode sources. (Groepaz's doc)
"Performs CMP and DEX at the same time, so that the MINUS sets the flag
like CMP, not SBC."las
las {addrmode} = Stores {addrmode}&S into A,X,S.
Known as "lar" in other undocumented opcode sources.
One source (which?) calls las "probably unreliable".[Unstable] "unstable in certain matters"; requires UNSTABLE directive.
ahx (A&H&X)
ahx {addrmode} = stores A&X&H into {addrmode}
"Sometimes the &H drops off. Page boundary crossing will not work as
expected; the bank where the value is stored may not be equal to the
value stored."shy (Store H&Y)
shy {addrmode} = stores Y&H into {addrmode}
"Sometimes the &H drops off. Page boundary crossing will not work as
expected; the bank where the value is stored may not be equal to the
value stored."shx (Store H&X)
shx {addrmode} = stores X&H into {addrmode}
"Sometimes the &H drops off. Page boundary crossing will not work as
expected; the bank where the value is stored may not be equal to the
value stored."tas
tas {addrmode} = Stores A&X into S, A&X&H into {addrmode}[Highly Unstable] "DO NOT USE!!!", "results are not predictable on some machines". YOU HAVE BEEN WARNED.
requires HUNSTABLE directive.
xaa (X And A) HIGHLY UNSTABLE!!!
xaa #{immediate} = X&#{immediate}
Known as "ane" in other undocumented opcode sources. (Groepaz's doc)lax is currently not supported.
INCLUDE/INCSRC INCBIN/BIN
Filenames can be double-quoted, permitting names that contain
spaces, ex.:
INCLUDE "some file.bin"
INCBIN "some file.bin"
INCBIN "some file.bin", $400
INCBIN "some file.bin", $200, $2000IGNORENL/ENDINL
Suppresses output of any labels when exporting FCEUX .nl files.
Useful for defining labels that may conflict with zero page addresses.
; don't show these button masks in the .nl file
IGNORENL
PAD_A = %10000000
PAD_B = %01000000
PAD_SELECT = %00100000
PAD_START = %00010000
PAD_UP = %00001000
PAD_DOWN = %00000100
PAD_LEFT = %00000010
PAD_RIGHT = %00000001
ENDINLUNSTABLE
Enables use of somewhat unstable 6502 opcodes.
; use some unstable undocumented instructions
ldy #0
ldx #1
ahx example,y
shy example,x
shx example,y
tas example,yHUNSTABLE
Enables use of highly unstable 6502 opcodes.
; throw caution to the wind and use xaa
HUNSTABLE
xaa #7Note that using an iNES header is optional; it's only inserted if at least one of these following directives is used.
INESPRG x Number of PRG ROM banks in a NES ROM.
INESCHR x Number of CHR ROM banks in a NES ROM.
INESMAP x Mapper number of NES ROM.
INESMIR x Mirroring mode of a NES ROM.
NES2CHRRAM x Amount of CHR RAM used by a NES ROM.
NES2PRGRAM x Amount of PRG RAM used by a NES ROM.
NES2SUB x Submapper number of NES ROM.
NES2TV x TV mode of NES ROM: NTSC, PAL, or both (0, 1 or 2) ('N', 'P' or 'B')
NES2VS Sets ROM to use the Vs. Unisystem.
NES2BRAM x Amount of battery-packed PRG RAM in NES ROM.
NES2CHRBRAM x Amount of battery-packed CHR RAM in NES ROM.
//todo - do NOT open source files in update mode, since we do not want to modify them in any way //todo - don't open text files in binary mode //todo - thoroughly verify operation on big-endian machine //todo - avoid putting special values into pointers, like (char*)1 //todo - don't depend on platform supporting unaligned objects //todo - make everything static //todo - redundant parsing code is all over the place, try clean it up / consolidate