mirror of https://github.com/cc65/cc65.git
64 lines
1.5 KiB
ArmAsm
64 lines
1.5 KiB
ArmAsm
;
|
|
; 2020-07-14, Groepaz
|
|
;
|
|
; void cpeeks (char* s, unsigned length);
|
|
;
|
|
; get string from current position, do NOT advance cursor
|
|
|
|
.export _cpeeks
|
|
|
|
.import popax
|
|
.importzp ptr1, ptr2, tmp1, tmp2
|
|
|
|
.macpack generic
|
|
|
|
.include "pce.inc"
|
|
.include "extzp.inc"
|
|
|
|
_cpeeks:
|
|
eor #<$FFFF ; counting a word upward is faster
|
|
sta ptr2 ; so, we use -(length + 1)
|
|
txa
|
|
eor #>$FFFF
|
|
sta ptr2+1
|
|
|
|
st0 #VDC_MARR ; Memory-Address Read
|
|
ldy SCREEN_PTR
|
|
ldx SCREEN_PTR+1
|
|
sty VDC_DATA_LO
|
|
stx VDC_DATA_HI
|
|
|
|
st0 #VDC_VRR ; VRAM Read Register
|
|
|
|
jsr popax
|
|
sta tmp1 ; (will be a .Y index)
|
|
stx ptr1+1
|
|
|
|
ldx #<$0000
|
|
stx ptr1
|
|
beq L2 ; branch always
|
|
|
|
L3: ldy tmp2
|
|
lda VDC_DATA_LO ; get character
|
|
bit VDC_DATA_HI ; we need to "read" the highbyte to advance the address
|
|
iny
|
|
sty tmp2
|
|
and #<~$80 ; remove reverse bit
|
|
|
|
ldy tmp1
|
|
sta (ptr1),y
|
|
iny
|
|
bne L1
|
|
inc ptr1+1
|
|
L1: sty tmp1
|
|
|
|
L2: inc ptr2 ; count length
|
|
bne L3
|
|
inc ptr2+1
|
|
bne L3
|
|
|
|
txa ; terminate the string
|
|
ldy tmp1
|
|
sta (ptr1),y
|
|
rts
|