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fixed behavior of memset((void*)-1, ch, 0) along with bzero and wmemset #668

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Merged
merged 1 commit into from
Nov 10, 2025
Merged

fixed behavior of memset((void*)-1, ch, 0) along with bzero and wmemset #668

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25 changes: 13 additions & 12 deletions src/libc/bzero.src
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Original file line number Diff line number Diff line change
Expand Up @@ -14,8 +14,8 @@ _bzero:
add hl, sp
ld bc, (hl) ; size
inc bc
cpd ; dec hl
ret po ; zero size
cpd ; dec hl
ret po ; zero size
dec hl
dec hl
ld de, (hl) ; buf
Expand All @@ -31,20 +31,21 @@ else
_bzero:
ld hl, 6
add hl, sp
ld bc, (hl)
ld bc, (hl) ; BC = size
dec hl
dec hl
dec hl
ld hl, (hl)
cpi
add hl, bc
ret c
dec hl
ld de, (hl) ; DE = dst
scf
sbc hl, hl
add hl, bc ; HL = size - 1
ret nc ; size == 0
add hl, de ; HL = dst + size - 1
ld (hl), 0
ret po
push hl
pop de
dec de
cpd ; HL = dst + size - 2, BC = size - 1
ex de, hl ; DE = dst + size - 2, HL = dst
ret po ; return if size == 1
add hl, bc ; HL = dst + size - 1
lddr
ret

Expand Down
27 changes: 14 additions & 13 deletions src/libc/memset.src
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Expand Up @@ -5,19 +5,20 @@
public _memset

_memset:
ld iy, 0
ld iy, -1
add iy, sp
ld hl, (iy + 3)
ld bc, (iy + 9)
cpi
add hl, bc
ret c
dec hl
ld e, (iy + 6)
ld (hl), e
ret po
push hl
pop de
dec de
ld bc, (iy + 10) ; BC = size
sbc hl, hl ; always resets overflow
add hl, bc ; HL = size - 1
ld de, (iy + 4) ; DE = dst
jr nc, .zero_size
ld a, (iy + 7)
add hl, de ; HL = dst + size - 1
ld (hl), a
cpd ; HL = dst + size - 2, BC = size - 1
.zero_size:
ex de, hl ; DE = dst + size - 2, HL = dst
ret po ; return if size == 1
add hl, bc ; HL = dst + size - 1
lddr
ret
49 changes: 23 additions & 26 deletions src/libc/wmemset.src
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Expand Up @@ -6,33 +6,30 @@

; wchar_t *wmemset(wchar_t *dst, wchar_t ch, size_t count)
_wmemset:
pop iy, hl, de, bc
push bc, de, hl, iy
; BC = count
; DE = ch
; HL = dst

; count *= sizeof(wchar_t)
cpi ; hl++ bc--
add hl, bc ; HL = (dst + 1) + (count - 1) = dst + count
ret c ; bc is zero
add hl, bc ; HL = dst + count + (count - 1) = dst + 2 * count - 1

; hl += (count - 1) * 2 + 1
; count -= 2
ld (hl), d ; upper 8 bits
dec hl
ld (hl), e ; lower 8 bits
ret po ; only one element needs to be written

; write multiple elements
push hl
pop de
inc hl
dec de

push bc
ld iy, -1
add iy, sp
ld bc, (iy + 10) ; BC = count
sbc hl, hl
add hl, bc ; HL = count - 1
ex de, hl ; DE = count - 1
ld hl, (iy + 4) ; HL = dst
ret nc ; count == 0
add hl, bc ; HL = dst + count
add hl, de ; HL = dst + 2 * count - 1
ex de, hl ; DE = dst + 2 * count - 1
lea hl, iy + 8 ; HL = &upper_byte
ldd
; HL = &lower_byte
; DE = dst + 2 * count - 2
ld a, (hl)
ld (de), a
push de
pop hl
ret po ; count == 1
inc hl ; HL = dst + 2 * count - 1
dec de ; DE = dst + 2 * count - 3
; use lddr twice
push bc
lddr
pop bc
lddr
Expand Down
9 changes: 9 additions & 0 deletions test/standalone/asprintf_fprintf/src/main.c
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Expand Up @@ -521,6 +521,15 @@ int mempcpy_test(void) {
int bzero_test(void) {
char truth[32];
char data[32];

// test zero size cases
C(T_memset(NULL_ptr, 0xCE, 0) == NULL_ptr);
C(T_memset((void*)0xFFFFFF, 0xCE, 0) == (void*)0xFFFFFF);
C(T_memset((void*)0x000001, 0xCE, 0) == (void*)0x000001);
T_bzero(NULL_ptr, 0);
T_bzero((void*)0xFFFFFF, 0);
T_bzero((void*)0x000001, 0);

T_memset(data, 0x8F, sizeof(data));
T_memset(&truth[ 0], 0x8F, 8);
T_memset(&truth[ 2], 0x00, 1);
Expand Down
10 changes: 7 additions & 3 deletions test/standalone/wide_char/src/main.c
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Expand Up @@ -24,7 +24,7 @@
extern wchar_t * const PTR_000000;
extern wchar_t * const PTR_FFFFFF;

#if 0
#if 1

int T_wmemcmp(const wchar_t *s1, const wchar_t *s2, size_t n) __NOEXCEPT __attribute__((__pure__));
wchar_t * T_wmemchr(const wchar_t *ptr, int ch, size_t count) __NOEXCEPT __attribute__((__pure__));
Expand Down Expand Up @@ -182,6 +182,10 @@ int test_wmemset(void) {
test_printf("%p != %p\n", ptr, (void*)0xC0FFEE);
return __LINE__;
}
C(wmemset(PTR_000000, 0x71CE, 0) == PTR_000000);
C(wmemset(PTR_FFFFFF, 0x71CE, 0) == PTR_FFFFFF);
C(wmemset((void*)0x000001, 0x71CE, 0) == (void*)0x000001);

wchar_t data[192 + 1];
memset(data, 0xBC, sizeof(data));
wmemset(wmemset(&data[ 0], 0x0012, 64) + 64, 0x0012, 64);
Expand All @@ -194,7 +198,7 @@ int test_wmemset(void) {
test_printf("%p != %p\n", res, &data[64]);
return __LINE__;
}

wchar_t truth[192 + 1];
memset(truth, 0xDE, sizeof(truth));
C(&truth[ 0] == wmemset(&truth[ 0], 0x0012, 64));
Expand Down Expand Up @@ -230,7 +234,7 @@ int test_wmemset(void) {
int test_wmemmove(void) {
wchar_t move_str[] =
{0x000F, 0x111F, 0x222F, 0x333F, 0x444F, 0x555F, 0x666F, 0x777F, 0x888F, 0x999F};
const wchar_t truth_str[] =
const wchar_t truth_str[] =
{0x999F, 0x333F, 0x444F, 0x444F, 0x555F, 0x444F, 0x555F, 0x666F, 0x888F, 0x999F};
C(move_str + 5 == wmemmove(move_str + 5, move_str + 4, 3));
C(move_str + 3 == wmemmove(move_str + 3, move_str + 3, 0));
Expand Down
17 changes: 17 additions & 0 deletions test/standalone/wide_char/src/rename.asm
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Expand Up @@ -9,3 +9,20 @@ _PTR_000000:
public _PTR_FFFFFF
_PTR_FFFFFF:
db $FF, $FF, $FF

section .text

public _T_wmemset, _T_wmemcpy, _T_wmemmove, _T_wmemcmp, _T_wmemchr
public _T_wcslen, _T_wcsnlen

_T_wmemset := _wmemset
_T_wmemcpy := _wmemcpy
_T_wmemmove := _wmemmove
_T_wmemcmp := _wmemcmp
_T_wmemchr := _wmemchr

_T_wcslen := _wcslen
_T_wcsnlen := _wcsnlen

extern _wmemset, _wmemcpy, _wmemmove, _wmemcmp, _wmemchr
extern _wcslen, _wcsnlen
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