mirror of https://github.com/marketideas/qasm.git
115 lines
4.0 KiB
ArmAsm
115 lines
4.0 KiB
ArmAsm
; Copyright 2018 faddenSoft. All Rights Reserved.
|
|
; See the LICENSE.txt file for distribution terms (Apache 2.0).
|
|
;
|
|
; Assembler: Merlin 32
|
|
|
|
xc off
|
|
xc
|
|
xc
|
|
mx %11
|
|
org $1000
|
|
|
|
; 65816 mode with short regs
|
|
clc
|
|
xce
|
|
sep #$30
|
|
mx %11
|
|
|
|
jsr test1
|
|
jsr test2
|
|
jsr test3
|
|
jsr test4
|
|
jsr test5
|
|
rts
|
|
|
|
; TEST #1: simple example
|
|
test1 lda #$00
|
|
dfb $2c ;BIT abs
|
|
:inner lda #$01
|
|
beq :inner
|
|
rts
|
|
|
|
; TEST #2: embedded with break path
|
|
;
|
|
; Example inspired by incorrect analysis...
|
|
;
|
|
; The code analyzer sees:
|
|
; beq {+03} ;jumps to the $8f
|
|
; lda #$00
|
|
; brk $8f
|
|
; and stops, then pursues the branch. If we try to walk from top
|
|
; to bottom, skipping forward by the full length of an instruction,
|
|
; we'll appear to find ourselves in the middle of an embedded
|
|
; instruction.
|
|
;
|
|
; This is different from the typical embedded instruction,
|
|
; where the inner is contained entirely within the outer.
|
|
test2 sep #$30 ;short regs
|
|
mx %00 ;pretend they're long
|
|
|
|
lda $00 ;load something to scramble flags
|
|
beq :store
|
|
lda #$0000
|
|
:store stal $012345
|
|
rts
|
|
|
|
; TEST #3: embedded with non-instruction byte
|
|
;
|
|
; The code analyzer sees two paths, involving the three bytes.
|
|
; The first is the three-byte JSR, the second is the one-byte
|
|
; RTS. The third NOP byte is never "executed" by the analyzer,
|
|
; but because of the way we display embedded instructions it
|
|
; gets put on its own line. Since it's not an instruction start
|
|
; or a data item, things get confused. (This is referred to as
|
|
; an "embedded orphan" in the code.)
|
|
|
|
test3 dfb $20 ;JSR
|
|
:mid dfb $60 ;RTS
|
|
dfb $ea ;NOP
|
|
bra :mid
|
|
|
|
|
|
; TEST #4: overlapping chain
|
|
;
|
|
; Each BIT instruction is three bytes, and each byte is a branch target,
|
|
; so we get a string of embedded instructions.
|
|
test4
|
|
:bits hex 2c2c2c2c2c2c2c2c2ceaea
|
|
asl
|
|
bcc :bits
|
|
asl
|
|
bcc :bits+1
|
|
asl
|
|
bcc :bits+2
|
|
asl
|
|
bcc :bits+3
|
|
asl
|
|
bcc :bits+4
|
|
asl
|
|
bcc :bits+5
|
|
asl
|
|
bcc :bits+6
|
|
asl
|
|
bcc :bits+7
|
|
asl
|
|
bcc :bits+8
|
|
asl
|
|
bcc :bits+9
|
|
rts
|
|
|
|
; TEST #5: another overlap
|
|
;
|
|
; Trying to be a little different.
|
|
test5 dfb $2c
|
|
:mid1 nop
|
|
hex ad
|
|
:mid2 lda $00
|
|
asl
|
|
bcc :mid1
|
|
asl
|
|
bcc :mid2
|
|
|
|
; TEST #6: "embedded" off the end of the file
|
|
dfb $af ;ldal
|
|
|