6502/COMMON
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Merge pull request #22 from Russell-S-Harper/development

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Russell-S-Harper 2018-08-23 20:00:22 -04:00 committed by GitHub
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2 changed files with 6 additions and 6 deletions
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4
README.md
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@ -16,7 +16,7 @@ Why 6502 and not, for example, x86?
* 6502 assembler is very easy and has a large archive of existing functions
* existing 6502 SWEET16 already has the “hard work” done
* interesting to see it run in newer versions of 6502 processors
* interesting to see it run in newer faster versions of 6502 processors
* how do you think Bender does what he does? (or the Terminator!)
In progress:
@ -34,7 +34,7 @@ The meat of the project:
Auxiliary:
* `emulator/*`: 6502 emulator (borrowed Mike Chambers’ Fake6502 CPU emulator v1.1 ©2011)
* `xa-pre-process/*`: utility `xapp` to convert 32-bit fixed decimal quantities so that `xa` can use them
* `xa-pre-process/*`: my utility `xapp` to convert 32-bit fixed decimal quantities so that `xa` can use them
Right now, for testing purposes, the code builds everything into one file `system.obj` and runs the code in the last block loaded, in this case, the code corresponding to `page6.src`. Eventually will support decoupling of system and application files. Application files will be inherently relocatable.

8
common/common.asm
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@ -43,7 +43,7 @@ _3 TAX ; save operand for later
ASL ; shift to get offset to register
ASL
TAX ; back to index
RTS ; "return" to routine
RTS ; "return" to routine
_4 TXA ; get operand
ASL ; shift to get offset to 0X instructions
TAY
@ -52,7 +52,7 @@ _4 TXA ; get operand
LDA FN_0X,Y ; push low address
PHA
TXA ; restore operand
RTS ; "return" to routine
RTS ; "return" to routine
_5 TXA ; get operand
AND #$F ; mask to get index
ASL ; shift to get offset to FX instructions
@ -408,7 +408,7 @@ _ABSX .( ; sets register at X to absolute value
RTS
.)
_BKRRD .( ; implement banker's rounding on quadword pointed by X
_BKRRD .( ; implement banker's rounding on quad-word pointed by X
; The logic table below shows the expected results. The only differences are
; when the least significant byte (LSB) is 128 and the second byte (2B) is even
@ -736,7 +736,7 @@ _6 JMP _RETI0X ; pull X, transfer I0 to r register, let it handle the return
_MOD .(
RTS
.)
_ESC .( ; ESC 00 - escape back into regular assembler
PLA ; discard the COMMON _1 return address
PLA