1
0
mirror of https://github.com/cc65/cc65.git synced 2024-12-24 11:31:31 +00:00
cc65/libsrc/runtime/icmp.s
uz 6a26b6e3b4 Added tosicmp0, a special entry point that clears the X register.
git-svn-id: svn://svn.cc65.org/cc65/trunk@4005 b7a2c559-68d2-44c3-8de9-860c34a00d81
2009-08-14 22:08:28 +00:00

48 lines
726 B
ArmAsm

;
; Piotr Fusik, 15.04.2002
; originally by Ullrich von Bassewitz
;
; Integer compare function - used by the compare operators
;
.export tosicmp, tosicmp0
.importzp sp, sreg
tosicmp0:
ldx #$00
tosicmp:
sta sreg
stx sreg+1 ; Save ax
ldy #$00
lda (sp),y ; Get low byte
tax
inc sp ; 5
bne @L1 ; 3
inc sp+1 ; (5)
@L1:
lda (sp),y ; Get high byte
inc sp ; 5
bne @L2 ; 3
inc sp+1 ; (5)
; Do the compare.
@L2: sec
sbc sreg+1 ; Compare high byte
bne @L4
cpx sreg ; Compare low byte
beq @L3
adc #$FF ; If the C flag is set then clear the N flag
ora #$01 ; else set the N flag
@L3: rts
@L4: bvc @L3
eor #$FF ; Fix the N flag if overflow
ora #$01 ; Clear the Z flag
rts