Rename dirs

lib/string.c

@@ -0,0 +1,141 @@
+#include <zinnia/compiler.h>
+#include <zinnia/utils.h>
+#include <stddef.h>
+#include <stdint.h>
+
+[[__hot]]
+size_t strlen(const char* str) {
+    size_t result = 0;
+    while (*str++) {
+        result++;
+    }
+    return result;
+}
+
+[[__hot]]
+size_t strnlen(const char* str, size_t len) {
+    size_t result = 0;
+    while (result < len && *str++) {
+        result++;
+    }
+    return result;
+}
+
+[[__hot]]
+int memcmp(const void* s1, const void* s2, size_t size) {
+    const uint8_t* s1ptr = s1;
+    const uint8_t* s2ptr = s2;
+
+    for (size_t i = 0; i < size; i++) {
+        if (s1ptr[i] != s2ptr[i])
+            return (int)s1ptr[i] - (int)s2ptr[i];
+    }
+    return 0;
+}
+
+typedef size_t word_t [[__may_alias]]
+;
+
+[[__hot]]
+void* memcpy(void* restrict dest, const void* restrict src, size_t n) {
+    uint8_t* d = dest;
+    const uint8_t* s = src;
+
+    // Word copies are only possible if both pointers can be aligned at the same time.
+    if (((uintptr_t)d - (uintptr_t)s) % sizeof(word_t) == 0) {
+        while (n && (uintptr_t)d % sizeof(word_t) != 0) {
+            *d++ = *s++;
+            n--;
+        }
+
+        word_t* word_dest = (word_t*)d;
+        const word_t* word_src = (const word_t*)s;
+        for (; n >= sizeof(word_t); n -= sizeof(word_t))
+            *word_dest++ = *word_src++;
+
+        d = (uint8_t*)word_dest;
+        s = (const uint8_t*)word_src;
+    }
+
+    while (n--)
+        *d++ = *s++;
+
+    return dest;
+}
+
+[[__hot]]
+void* memmove(void* dstptr, const void* srcptr, size_t size) {
+    uint8_t* dst = (uint8_t*)dstptr;
+    const uint8_t* src = (const uint8_t*)srcptr;
+
+    if ((uintptr_t)dst < (uintptr_t)src) {
+        for (size_t i = 0; i < size; i++)
+            dst[i] = src[i];
+    } else {
+        for (size_t i = size; i != 0; i--)
+            dst[i - 1] = src[i - 1];
+    }
+    return dstptr;
+}
+
+[[__hot]]
+void* memset(void* dest, int value, size_t n) {
+    uint8_t* d = dest;
+    const uint8_t byte = (uint8_t)value;
+
+    while (n && (uintptr_t)d % sizeof(word_t) != 0) {
+        *d++ = byte;
+        n--;
+    }
+
+    const word_t word_value = (SIZE_MAX / 0xFF) * byte;
+    word_t* word_dest = (word_t*)d;
+    for (; n >= sizeof(word_t); n -= sizeof(word_t))
+        *word_dest++ = word_value;
+
+    d = (uint8_t*)word_dest;
+    while (n--)
+        *d++ = byte;
+
+    return dest;
+}
+
+char* strncpy(char* restrict dst, const char* restrict src, size_t len) {
+    size_t src_len = strnlen(src, len);
+    memcpy(dst, src, src_len);
+    memset(dst + src_len, 0, len - src_len);
+    return dst;
+}
+
+int strncmp(const char* str1, const char* str2, size_t len) {
+    while (len && *str1 && (*str1 == *str2)) {
+        ++str1;
+        ++str2;
+        --len;
+    }
+    if (len == 0) {
+        return 0;
+    } else {
+        return (*(unsigned char*)str1 - *(unsigned char*)str2);
+    }
+}
+
+int strcmp(const char* str1, const char* str2) {
+    while (*str1 && (*str1 == *str2)) {
+        ++str1;
+        ++str2;
+    }
+    return (*(unsigned char*)str1 - *(unsigned char*)str2);
+}
+
+char* strchr(const char* s, int c) {
+    char ch = (char)c;
+    while (true) {
+        char cur = *s;
+        if (cur == ch)
+            return (char*)s;
+        if (cur == 0)
+            return nullptr;
+        s++;
+    }
+}