Main: move libc to "libc/"

libc/src/main.c

@@ -0,0 +1,123 @@
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <ctype.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+int atoi(const char *str)
+{
+    while (isspace(*str)) ++str;
+    bool is_negative = false;
+    switch (*str) {
+    case '-': is_negative = true; // fall through
+    case '+': ++str;
+    }
+    int result = 0;
+    while (isdigit(*str)) result = 10 * result - (*str++ - '0');
+    return is_negative ? result : -result;
+}
+
+int isdigit(const int c)
+{
+    return (unsigned)c - '0' < 10;
+}
+
+int isspace(const int c)
+{
+    return c == ' ' || (unsigned)c - '\t' < 5;
+}
+
+int memcmp(const void *s1, const void *s2, size_t n)
+{
+    for (const unsigned char *p1 = s1, *p2 = s2; n--; ++p1, ++p2) {
+        if (*p1 != *p2) return *p1 - *p2;
+    }
+    return 0;
+}
+
+void *memcpy(void *dest, const void *src, size_t n)
+{
+    char *dest_cell = dest;
+    char *src_cell = (char*)src;
+    while (n--) *dest_cell++ = *src_cell++;
+    return dest;
+}
+
+void *memmove(void *dest, const void *src, size_t n)
+{
+    char *dest_cell = dest;
+    char *src_cell = (char*)src;
+    if (dest_cell <= src_cell) {
+        while (n--) *dest_cell++ = *src_cell++;
+    } else {
+        dest_cell += n;
+        src_cell += n;
+        while (n--) *--dest_cell = *--src_cell;
+    }
+    return dest;
+}
+
+void *memset(void *s, int c, size_t n)
+{
+    char *ss = s;
+    while (n--) *ss++ = c;
+    return s;
+}
+
+int strcmp(const char *s1, const char *s2)
+{
+    for (; *s1; ++s1, ++s2) if (*s1 != *s2) return *s1 < *s2 ? -1 : 1;
+    return 0;
+}
+
+char *strcpy(char *dest, const char *src)
+{
+    char *tmp = dest;
+    while ((*dest++ = *src++) != '\0');
+    return tmp;
+}
+
+size_t strlen(const char *s)
+{
+    const char *ss = s;
+    while (*ss != '\0') ++ss;
+    return ss - s;
+}
+
+int strncmp(const char *s1, const char *s2, size_t n)
+{
+    for (; *s1 && n; ++s1, ++s2, --n) if (*s1 != *s2) return *s1 < *s2 ? -1 : 1;
+    return 0;
+}
+
+char *strncpy(char *dest, const char *src, size_t n)
+{
+    char *tmp = dest;
+    while (n-- && (*dest++ = *src++) != '\0');
+    return tmp;
+}
+
+size_t strnlen(const char *s, size_t maxlen)
+{
+    const char *ss = s;
+    while (*ss != '\0' && maxlen--) ++ss;
+    return ss - s;
+}
+
+char *strstr(const char *haystack, const char *needle)
+{
+    const size_t needle_slen = strlen(needle);
+    if (!needle_slen) return (char*)haystack;
+
+    size_t haystack_slen = strlen(haystack);
+    while (haystack_slen >= needle_slen) {
+        --haystack_slen;
+        if (!memcmp(haystack, needle, needle_slen)) return (char*)haystack;
+        ++haystack;
+    }
+
+    return NULL;
+}