+++ /dev/null
-;
-; Ullrich von Bassewitz, 17.06.1998
-;
-; int abs (int x);
-;
-
- .export _abs
- .import negax
-
-_abs: cpx #$00 ; test hi byte
- bpl L1
- jmp negax ; Negate if negative
-L1: rts
-
-
-
--- /dev/null
+;
+; Christian Krueger, 23-May-2018
+;
+; CC65 runtime: helper call for mod/div with signed ints
+;
+; When negating values, we will ignore the possibility here, that one of the
+; values is $8000, in which case the negate will fail.
+
+ .export absvaludiv
+ .import _abs, popax, udiv16
+ .importzp ptr1, ptr4
+
+
+absvaludiv:
+ jsr _abs
+ sta ptr4
+ stx ptr4+1 ; Save right absolute operand
+ jsr popax
+ jsr _abs
+ sta ptr1
+ stx ptr1+1 ; Save left absolute operand
+ jmp udiv16
;
-; Ullrich von Bassewitz, 07.08.1998
+; Christian Krueger, 24-May-2018
;
; CC65 runtime: division for signed ints
;
; When negating values, we will ignore the possibility here, that one of the
-; values if $8000, in which case the negate will fail.
+; values is $8000, in which case the negate will fail.
.export tosdiva0, tosdivax
- .import popsargs, udiv16, negax
- .importzp sreg, tmp1, tmp2
+ .import absvaludiv, negax
+ .importzp sp, ptr1, tmp1
tosdiva0:
ldx #0
tosdivax:
- jsr popsargs ; Get arguments from stack, adjust sign
- jsr udiv16 ; Do the division
- ldx sreg+1 ; Load high byte of result
-
-; Adjust the sign of the result. tmp1 contains the high byte of the left
-; operand, tmp2 contains the high byte of the right operand.
-
- lda tmp1
- eor tmp2
- bpl Pos ; Jump if sign of result positive
-
-; Result is negative
-
- lda sreg ; Load low byte of result
- jmp negax ; Adjust the sign
-
-; Result is positive
-
-Pos: lda sreg
+ pha ; check if high-bytes indicate
+ txa ; different sign, so that we
+ ldy #1 ; negate the result after the operation
+ eor (sp),y ; eor with lhs high byte
+ sta tmp1 ; save post negation indicator to tmp1
+ pla ; back to entry accu
+ jsr absvaludiv
+ ldx ptr1+1
+ lda ptr1
+ ldy tmp1 ; fetch idicator
+ bmi negate
rts
-
+negate: jmp negax
;
-; Ullrich von Bassewitz, 07.08.1998
+; Christian Krueger, 24-May-2018
;
; CC65 runtime: modulo operation for signed ints
;
; When negating values, we will ignore the possibility here, that one of the
-; values if $8000, in which case the negate will fail.
+; values is $8000, in which case the negate will fail.
.export tosmoda0, tosmodax
- .import popsargs, udiv16, negax
- .importzp ptr1, tmp1
+ .import absvaludiv, negax
+ .importzp sp, sreg, tmp1
tosmoda0:
ldx #0
tosmodax:
- jsr popsargs ; Get arguments from stack, adjust sign
- jsr udiv16 ; Do the division
- lda ptr1 ; Load low byte of result
- ldx ptr1+1 ; Load high byte of result
-
-; Adjust the sign of the result. tmp1 contains the high byte of the left
-; operand, tmp2 contains the high byte of the right operand. The sign of
-; the result of the modulo operation is the same as that of the left
-; operand
-
- bit tmp1
- bpl Pos ; Jump if sign of result positive
-
-; Result is negative
-
- jmp negax ; Adjust the sign
-
-; Result is positive
-
-Pos: rts
+; Prepare adjustment of the sign of the result. The sign of the result of the
+; modulo operation is the same as that of the left operand.
+
+ pha
+ ldy #1 ; prepare lhs operant hi-byte fetch
+ lda (sp),y
+ sta tmp1 ; save post negation indicator to tmp1
+ pla ; back to entry accu
+ jsr absvaludiv
+ ldx sreg+1 ; remainder to return registers
+ lda sreg
+ ldy tmp1 ; fetch idicator
+ bmi negate
+ rts
+negate: jmp negax
;
; CC65 runtime: Multiply the primary register by 3
;
+; Don't touch the Y-register here, the optimizer relies on it!
.export mulax3
.importzp ptr1
+++ /dev/null
-;
-; Ullrich von Bassewitz, 05.08.1998
-;
-; CC65 runtime: negation on ints
-;
-
- .export negax
-
-negax: clc
- eor #$FF
- adc #1
- pha
- txa
- eor #$FF
- adc #0
- tax
- pla
- rts
-
-
-
--- /dev/null
+;
+; Ullrich von Bassewitz, 05.08.1998
+;
+; int abs (int x);
+; and
+; CC65 runtime: negation on ints
+;
+
+ .export negax
+ .export _abs
+
+_abs: cpx #$00 ; test hi byte
+ bpl L1 ; don't touch if positive
+negax: clc
+ eor #$FF
+ adc #1
+ pha
+ txa
+ eor #$FF
+ adc #0
+ tax
+ pla
+ L1: rts
+
+
+
+++ /dev/null
-;
-; Ullrich von Bassewitz, 07.08.1998
-;
-; CC65 runtime: helper stuff for mod/div/mul with signed ints
-;
-
-; When negating values, we will ignore the possibility here, that one of the
-; values if $8000, in which case the negate will fail.
-
- .export popsargs
- .import negax, popax
- .importzp sreg, tmp1, tmp2, ptr4
-
-popsargs:
- stx tmp2 ; Remember sign
- cpx #0
- bpl L1
- jsr negax ; Negate accumulator
-L1: sta ptr4
- stx ptr4+1 ; Save right operand
-
- jsr popax
- stx tmp1 ; Remember sign
- cpx #0
- bpl L2
- jsr negax
-L2: sta sreg
- stx sreg+1
- rts
-
;
; CC65 runtime: division for unsigned ints
;
+; Don't use tmp1 here, the signed division tunnels data with it!
.export tosudiva0, tosudivax, udiv16
- .import popsreg
+ .import popptr1
.importzp sreg, ptr1, ptr4
tosudivax:
sta ptr4
stx ptr4+1 ; Save right operand
- jsr popsreg ; Get left operand
+ jsr popptr1 ; Get left operand
; Do the division
jsr udiv16
-; Result is in sreg, remainder in ptr1
+; Result is in ptr1, remainder in sreg
- lda sreg
- ldx sreg+1
+ lda ptr1
+ ldx ptr1+1
rts
;---------------------------------------------------------------------------
-; 16by16 division. Divide sreg by ptr4. Result is in sreg, remainder in ptr1
+; 16by16 division. Divide ptr1 by ptr4. Result is in ptr1, remainder in sreg
; (see mult-div.s from "The Fridge").
; This is also the entry point for the signed division
udiv16: lda #0
- sta ptr1+1
+ sta sreg+1
ldy #16
ldx ptr4+1
beq udiv16by8a
-L0: asl sreg
- rol sreg+1
- rol a
+L0: asl ptr1
rol ptr1+1
+ rol a
+ rol sreg+1
- pha
+ tax
cmp ptr4
- lda ptr1+1
+ lda sreg+1
sbc ptr4+1
bcc L1
- sta ptr1+1
- pla
+ sta sreg+1
+ txa
sbc ptr4
- pha
- inc sreg
+ tax
+ inc ptr1
-L1: pla
+L1: txa
dey
bne L0
- sta ptr1
+ sta sreg
rts
; 16by8 division
udiv16by8a:
-@L0: asl sreg
- rol sreg+1
+@L0: asl ptr1
+ rol ptr1+1
rol a
bcs @L1
cmp ptr4
bcc @L2
@L1: sbc ptr4
- inc sreg
+ inc ptr1
@L2: dey
bne @L0
- sta ptr1
+ sta sreg
rts
;
.export tosumoda0, tosumodax
- .import popsreg, udiv16
- .importzp ptr1, ptr4
+ .import popptr1, udiv16
+ .importzp sreg, ptr4
tosumoda0:
ldx #0
tosumodax:
sta ptr4
stx ptr4+1 ; Save right operand
- jsr popsreg ; Get right operand
+ jsr popptr1 ; Get right operand
; Do the division
jsr udiv16
-; Result is in sreg, remainder in ptr1
+; Result is in ptr1, remainder in sreg
- lda ptr1
- ldx ptr1+1
+ lda sreg
+ ldx sreg+1
rts
projects / cc65 / commitdiff