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Merge pull request #117 from gbowne1/klibc-strncpy

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[klibc] implment strncpy function
This commit is contained in:
Gregory Kenneth Bowne
2026-02-03 10:54:06 -08:00
committed by GitHub
parent 56faa3143d bfc9911a85
commit 3e6f8d0072
2 changed files with 48 additions and 31 deletions
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13
klibc/include/string.h
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@@ -3,12 +3,13 @@
#include <stddef.h> #include <stddef.h>
extern int memcmp(const void* s1, const void* s2, size_t n); extern int memcmp(const void *s1, const void *s2, size_t n);
extern void* memmove(void* dst, const void* src, size_t n); extern void *memmove(void *dst, const void *src, size_t n);
extern void* memcpy(void* dst, const void* src, size_t n); extern void *memcpy(void *dst, const void *src, size_t n);
extern void* memset(void* dst, int c, size_t n); extern void *memset(void *dst, int c, size_t n);
extern size_t strlen(const char* s); extern size_t strlen(const char *s);
extern int strcmp(const char* s1, const char* s2); extern int strcmp(const char *s1, const char *s2);
extern char *strncpy(char *dst, const char *src, size_t n);
#endif // CLASSICOS_KLIBC_STRING_H #endif // CLASSICOS_KLIBC_STRING_H

66
klibc/src/string.c
View File

@@ -1,8 +1,8 @@
#include <string.h> #include <string.h>
int memcmp(const void* s1, const void* s2, size_t n) { int memcmp(const void *s1, const void *s2, size_t n) {
const unsigned char* c1 = s1; const unsigned char *c1 = s1;
const unsigned char* c2 = s2; const unsigned char *c2 = s2;
int d = 0; int d = 0;
while (n--) { while (n--) {
@@ -13,9 +13,9 @@ int memcmp(const void* s1, const void* s2, size_t n) {
return d; return d;
} }
void* memmove(void* dst, const void* src, size_t n) { void *memmove(void *dst, const void *src, size_t n) {
const char* p = src; const char *p = src;
char* q = dst; char *q = dst;
#if defined(__i386__) || defined(__x86_64__) #if defined(__i386__) || defined(__x86_64__)
if (q < p) { if (q < p) {
__asm__ volatile("cld; rep; movsb" : "+c"(n), "+S"(p), "+D"(q)); __asm__ volatile("cld; rep; movsb" : "+c"(n), "+S"(p), "+D"(q));
@@ -41,19 +41,19 @@ void* memmove(void* dst, const void* src, size_t n) {
return dst; return dst;
} }
void* memcpy(void* dst, const void* src, size_t n) { void *memcpy(void *dst, const void *src, size_t n) {
const char* p = src; const char *p = src;
char* q = dst; char *q = dst;
#if defined(__i386__) #if defined(__i386__)
size_t nl = n >> 2; size_t nl = n >> 2;
__asm__ volatile("cld ; rep ; movsl ; movl %3,%0 ; rep ; movsb" __asm__ volatile("cld ; rep ; movsl ; movl %3,%0 ; rep ; movsb"
: "+c"(nl), "+S"(p), "+D"(q) : "+c"(nl), "+S"(p), "+D"(q)
: "r"(n & 3)); : "r"(n & 3));
#elif defined(__x86_64__) #elif defined(__x86_64__)
size_t nq = n >> 3; size_t nq = n >> 3;
__asm__ volatile("cld ; rep ; movsq ; movl %3,%%ecx ; rep ; movsb" __asm__ volatile("cld ; rep ; movsq ; movl %3,%%ecx ; rep ; movsb"
: "+c"(nq), "+S"(p), "+D"(q) : "+c"(nq), "+S"(p), "+D"(q)
: "r"((uint32_t)(n & 7))); : "r"((uint32_t)(n & 7)));
#else #else
while (n--) { while (n--) {
*q++ = *p++; *q++ = *p++;
@@ -63,20 +63,20 @@ void* memcpy(void* dst, const void* src, size_t n) {
return dst; return dst;
} }
void* memset(void* dst, int c, size_t n) { void *memset(void *dst, int c, size_t n) {
char* q = dst; char *q = dst;
#if defined(__i386__) #if defined(__i386__)
size_t nl = n >> 2; size_t nl = n >> 2;
__asm__ volatile("cld ; rep ; stosl ; movl %3,%0 ; rep ; stosb" __asm__ volatile("cld ; rep ; stosl ; movl %3,%0 ; rep ; stosb"
: "+c"(nl), "+D"(q) : "+c"(nl), "+D"(q)
: "a"((unsigned char)c * 0x01010101U), "r"(n & 3)); : "a"((unsigned char)c * 0x01010101U), "r"(n & 3));
#elif defined(__x86_64__) #elif defined(__x86_64__)
size_t nq = n >> 3; size_t nq = n >> 3;
__asm__ volatile("cld ; rep ; stosq ; movl %3,%%ecx ; rep ; stosb" __asm__ volatile("cld ; rep ; stosq ; movl %3,%%ecx ; rep ; stosb"
: "+c"(nq), "+D"(q) : "+c"(nq), "+D"(q)
: "a"((unsigned char)c * 0x0101010101010101U), : "a"((unsigned char)c * 0x0101010101010101U),
"r"((uint32_t)n & 7)); "r"((uint32_t)n & 7));
#else #else
while (n--) { while (n--) {
*q++ = c; *q++ = c;
@@ -86,15 +86,15 @@ void* memset(void* dst, int c, size_t n) {
return dst; return dst;
} }
size_t strlen(const char* s) { size_t strlen(const char *s) {
const char* ss = s; const char *ss = s;
while (*ss) ss++; while (*ss) ss++;
return ss - s; return ss - s;
} }
int strcmp(const char* s1, const char* s2) { int strcmp(const char *s1, const char *s2) {
const unsigned char* c1 = (const unsigned char*)s1; const unsigned char *c1 = (const unsigned char *)s1;
const unsigned char* c2 = (const unsigned char*)s2; const unsigned char *c2 = (const unsigned char *)s2;
unsigned char ch; unsigned char ch;
int d = 0; int d = 0;
@@ -105,3 +105,19 @@ int strcmp(const char* s1, const char* s2) {
return d; return d;
} }
char *strncpy(char *dst, const char *src, size_t n) {
char *q = dst;
const char *p = src;
char ch;
while (n) {
n--;
*q++ = ch = *p++;
if (!ch) break;
}
memset(q, 0, n);
return dst;
}