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assem

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This commit is contained in:
Irmen de Jong 2021-01-10 03:44:10 +01:00
parent 79782ad547
commit 1ef9b8be61
1 changed files with 104 additions and 13 deletions
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113
examples/cx16/assembler/assem.p8
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@ -5,6 +5,7 @@
%zeropage basicsafe
%option no_sysinit
; TODO : NOTE: treat $0a (10 - line feed) and $0c (13 - normal petscii Return) both as line separators
main {
@ -21,7 +22,7 @@ main {
textparse {
; byte counts per address mode id:
ubyte[16] operand_size = [0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 1, 1, 1]
ubyte[16] operand_size = [0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 1, 1, 2]
str input_line = "?" * 40
uword[3] word_addrs
@ -161,9 +162,8 @@ textparse {
sub parse_operand(uword operand_ptr) -> ubyte {
; parses the operand. Returns 2 things:
; - addressing mode id as result value or 0 when error
; - addressing mode id as result value or 0 (am_Invalid) when error
; - operand numeric value in cx16.r15 (if applicable)
; TODO
ubyte firstchr = @(operand_ptr)
ubyte parsed_len
@ -180,24 +180,115 @@ textparse {
}
}
'a' -> {
; possibly Accumulator operand
; TODO parse
return instructions.am_Acc
if not @(operand_ptr+1)
return instructions.am_Acc ; Accumulator - no value.
; TODO its a symbol/label, immediate or indexed addressing
txt.print("TODO symbol: ")
txt.print(operand_ptr)
txt.nl()
}
'(' -> {
; various forms of indirect
; TODO parse number and other stuff
cx16.r15 = $98ab
operand_ptr++
parsed_len = conv.any2uword(operand_ptr)
if parsed_len {
operand_ptr+=parsed_len
if msb(cx16.r15) {
; absolute indirects
if str_is1(operand_ptr, ')')
return instructions.am_Ind
if str_is3(operand_ptr, ",x)")
return instructions.am_IaX
} else {
; zero page indirects
if str_is1(operand_ptr, ')')
return instructions.am_Izp
if str_is3(operand_ptr, ",x)")
return instructions.am_IzX
if str_is3(operand_ptr, "),y")
return instructions.am_IzY
}
}
}
'$', '%', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' -> {
; address optionally followed by ,x or ,y
; TODO Parse
cx16.r0 = $9988
parsed_len = conv.any2uword(operand_ptr)
if parsed_len {
operand_ptr += parsed_len
txt.print("abs-restoperand=")
txt.print(operand_ptr)
txt.nl()
if msb(cx16.r15) {
; absolute or abs indirects
if @(operand_ptr)==0
return instructions.am_Abs
if str_is2(operand_ptr, ",x")
return instructions.am_AbsX
if str_is2(operand_ptr, ",y")
return instructions.am_AbsY
} else {
; zero page or zp indirects
if @(operand_ptr)==0
return instructions.am_Zp
if str_is2(operand_ptr, ",x")
return instructions.am_ZpX
if str_is2(operand_ptr, ",y")
return instructions.am_ZpY
}
}
return 0
}
}
return instructions.am_Invalid
}
asmsub str_is1(uword st @R0, ubyte char @A) clobbers(Y) -> ubyte @A {
%asm {{
cmp (cx16.r0)
bne +
ldy #1
lda (cx16.r0),y
bne +
lda #1
rts
+ lda #0
rts
}}
}
asmsub str_is2(uword st @R0, uword compare @AY) clobbers(Y) -> ubyte @A {
%asm {{
sta P8ZP_SCRATCH_W1
sty P8ZP_SCRATCH_W1+1
ldy #0
jmp str_is3._is_2_entry
}}
}
asmsub str_is3(uword st @R0, uword compare @AY) clobbers(Y) -> ubyte @A {
%asm {{
sta P8ZP_SCRATCH_W1
sty P8ZP_SCRATCH_W1+1
lda (cx16.r0)
cmp (P8ZP_SCRATCH_W1)
bne +
ldy #1
_is_2_entry
lda (cx16.r0),y
cmp (P8ZP_SCRATCH_W1),y
bne +
iny
lda (cx16.r0),y
cmp (P8ZP_SCRATCH_W1),y
bne +
iny
lda (cx16.r0),y
bne +
lda #1
rts
+ lda #0
rts
}}
}
sub emit(ubyte value) {