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Fixed __ldvrmu calling convention and __ldiv (#793) #794

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Merged
mateoconlechuga merged 1 commit into from
Apr 24, 2026
+105 −90
Merged

Fixed __ldvrmu calling convention and __ldiv (#793) #794

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8 changes: 6 additions & 2 deletions src/crt/ldivu.src
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Original file line number Diff line number Diff line change
Expand Up @@ -10,14 +10,15 @@

.else

; REMEMBER to keep ldivu.src, lremu.src, and ldiv.src in sync with this choice
.if 1

__ldivu:
; I: EUHL=dividend, AUBC=divisor
; O: euhl=EUHL/AUBC
push bc

call __ldvrmu
call __ldivu_lremu_common

ld a, b
pop bc
Expand All @@ -26,6 +27,8 @@ __ldivu:
ei
ret

.extern __ldivu_lremu_common

.else

__ldivu:
Expand All @@ -41,8 +44,9 @@ __ldivu:
pop hl

ret
.endif

.extern __ldvrmu

.endif

.endif
86 changes: 86 additions & 0 deletions src/crt/ldivu_lremu_common.src
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Original file line number Diff line number Diff line change
@@ -0,0 +1,86 @@
.assume adl=1

.section .text

.global __ldivu_lremu_common
.type __ldivu_lremu_common, @function

;;; struct u32div_t {
;;; uint32_t rem;
;;; uint32_t quot;
;;; };
;;; u32div_t _ldivu_lremu_common(uint32_t dividend, uint32_t divisor) {

__ldivu_lremu_common:
; Similar to __ldvrmu but faster and with a different calling convention.
; Note: Uses shadow registers and disables interrupts.
; I: EUHL=dividend, AUBC=divisor
; O: a[uhl']=EUHL%AUBC, bcu=0, b=A, c=?, euhl=EUHL/AUBC, eubc'=AUBC, zf=!IEF2

;;; u32div_t result;
;;; result.quot = dividend;
; euhl : result.quot

push bc

ld c, a ; c = A
ld a, i ; a = I
; pf = IEF2
di

ld a, c ; a = A
exx
pop bc
ld e, a ; eubc' : divisor

push af

;;; result.rem = 0;
xor a, a
sbc hl, hl ; auhl' : result.rem

;;; int i = 32;
exx
ld b, 32 ; b : i

;;; do {
.L.c.loop:

;;; bool dividendBit = result.quot >> 31;
;;; result.quot <<= 1;
add hl, hl
rl e
;;; result.rem = (result.rem << 1) + dividendBit;
exx
adc hl, hl
adc a, a

;;; bool quotBit = result.rem >= divisor;
;;; result.rem -= divisor;
sbc hl, bc
sbc a, e

;;; if (!quotBit) {
jr nc, .L.c.restore_skip
;;; result.rem += divisor;
add hl, bc
adc a, e
;;; }
.L.c.restore_skip:

;;; if (quotBit) {
exx
jr c, .L.c.skip
;;; result.quot++;
inc l
;;; }
.L.c.skip:

;;; } while (--i != 0);
djnz .L.c.loop

;;; return result;
pop bc
bit 2, c
ret
;;; }
85 changes: 1 addition & 84 deletions src/crt/ldvrmu.src
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Original file line number Diff line number Diff line change
@@ -1,11 +1,7 @@
.assume adl=1

.section .text
;;; struct u32div_t {
;;; uint32_t rem;
;;; uint32_t quot;
;;; };
;;; u32div_t _ldvrmu(uint32_t dividend, uint32_t divisor) {

.global __ldvrmu
.type __ldvrmu, @function

Expand All @@ -15,83 +11,6 @@

.else

; REMEMBER to also modify ldivu.src, lremu.src, and ldiv.src if you change this
.if 1

__ldvrmu:
; I: EUHL=dividend, AUBC=divisor
; O: a[uhl']=EUHL%AUBC, bcu=0, b=A, c=?, euhl=EUHL/AUBC, eubc'=AUBC, zf=!IEF2

;;; u32div_t result;
;;; result.quot = dividend;
; euhl : result.quot

push bc

ld c, a ; c = A
ld a, i ; a = I
; pf = IEF2
di

ld a, c ; a = A
exx
pop bc
ld e, a ; eubc' : divisor

push af

;;; result.rem = 0;
xor a, a
sbc hl, hl ; auhl' : result.rem

;;; int i = 32;
exx
ld b, 32 ; b : i

;;; do {
.L.c.loop:

;;; bool dividendBit = result.quot >> 31;
;;; result.quot <<= 1;
add hl, hl
rl e
;;; result.rem = (result.rem << 1) + dividendBit;
exx
adc hl, hl
adc a, a

;;; bool quotBit = result.rem >= divisor;
;;; result.rem -= divisor;
sbc hl, bc
sbc a, e

;;; if (!quotBit) {
jr nc, .L.c.restore_skip
;;; result.rem += divisor;
add hl, bc
adc a, e
;;; }
.L.c.restore_skip:

;;; if (quotBit) {
exx
jr c, .L.c.skip
;;; result.quot++;
inc l
;;; }
.L.c.skip:

;;; } while (--i != 0);
djnz .L.c.loop

;;; return result;
pop bc
bit 2, c
ret
;;; }

.else

__ldvrmu:
; I: EUHL=dividend, AUBC=divisor
; O: auhl=EUHL%AUBC, euix=EUHL/AUBC, iyh=A, iyl=0
Expand Down Expand Up @@ -128,5 +47,3 @@ __ldvrmu:
ret

.endif

.endif
8 changes: 6 additions & 2 deletions src/crt/lremu.src
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Original file line number Diff line number Diff line change
Expand Up @@ -10,12 +10,13 @@

.else

; REMEMBER to keep ldivu.src, lremu.src, and ldiv.src in sync with this choice
.if 1

__lremu:
; I: EUHL=dividend, AUBC=divisor
; O: euhl=EUHL%AUBC
call __ldvrmu
call __ldivu_lremu_common
ld e, a
push de
exx
Expand All @@ -26,6 +27,8 @@ __lremu:
ei
ret

.extern __ldivu_lremu_common

.else

__lremu:
Expand All @@ -41,8 +44,9 @@ __lremu:
pop iy
pop ix
ret
.endif

.extern __ldvrmu

.endif

.endif
8 changes: 6 additions & 2 deletions src/libc/ldiv.src
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
.global _ldiv
.type _ldiv, @function

; REMEMBER to keep ldivu.src, lremu.src, and ldiv.src in sync with this choice
.if 1

_ldiv:
Expand All @@ -27,7 +28,7 @@ _ldiv:
bit 7, e
call __ldivs_lrems_common

call __ldvrmu
call __ldivu_lremu_common

exx
ld e, a
Expand All @@ -53,6 +54,8 @@ _ldiv:
.L.ei_skip:
jp (hl)

.extern __ldivu_lremu_common

.else

_ldiv:
Expand Down Expand Up @@ -111,8 +114,9 @@ _ldiv:
push de
jp (hl)

.extern __ldvrmu

.endif

.extern __ldivs_lrems_common
.extern __ldvrmu
.extern __lneg
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