From aaf7355c5ededfcdc877c7f2989fb1ba02dfb848 Mon Sep 17 00:00:00 2001
From: Danny Holman <dholman@gymli.org>
Date: Mon, 27 May 2024 13:53:52 -0500
Subject: libk: create a subset libc for kernel use

Create a subset of the C library for use inside the kernel.

Signed-off-by: Danny Holman <dholman@gymli.org>
---
 libk/string.c | 133 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 libk/string.c

(limited to 'libk/string.c')

diff --git a/libk/string.c b/libk/string.c
new file mode 100644
index 0000000..be59397
--- /dev/null
+++ b/libk/string.c
@@ -0,0 +1,133 @@
+#include <libk/string.h>
+
+int memcmp(const void *str1, const void *str2, size_t n) {
+        unsigned char const *p1 = str1;
+        unsigned char const *p2 = str2;
+        int ret = 0;
+
+        if (str1 == str2)
+                return 0;
+
+        while (n > 0) {
+                if (*p1 != *p2) {
+                        ret = (*p1 > *p2)?1:-1;
+                        break;
+                }
+                n--;
+                p1++;
+                p2++;
+        }
+        return ret;
+}
+
+void* memcpy(void* __restrict dest, const void* __restrict src, size_t n) {
+        if (dest == src)
+                return dest;
+
+        unsigned char *pdest = dest;
+        unsigned char const *psrc = src;
+        for (size_t i = 0; i < n; i++)
+                pdest[i] = psrc[i];
+        return dest;
+}
+
+char* strncpy(char* __restrict dest, const char* __restrict src, size_t n) {
+        for (size_t i = 0; i < n; i++) {
+                if (src[i] == '\0')
+                        break;
+                dest[i] = src[i];
+        }
+        return dest;
+}
+
+char* strcpy(char* __restrict dest, const char* __restrict src) {
+        return (char*)memcpy(dest, src, strlen(src));
+}
+
+char* strcat(char* __restrict dest, const char* __restrict src) {
+        return (char*)memcpy(&dest[strlen(dest)], src, strlen(src));
+}
+
+char* strncat(char* __restrict dest, const char* __restrict src, size_t n) {
+        return (char*)memcpy(&dest[strlen(dest)], src, n);
+}
+
+void* memmove(void* __restrict dest, const void* __restrict src, size_t n) {
+        if (dest == src)
+                return dest;
+
+        unsigned char const *psrc = src;
+        unsigned char buffer[n];
+
+        for (size_t i = 0; i < n; i++)
+                buffer[i] = psrc[i];
+        return memcpy(dest, (void*)buffer, n);
+}
+
+void* memset(void *str, int c, size_t n) {
+        unsigned char *p = str;
+        for (size_t i = 0; i < n; i++)
+                p[i] = (unsigned char)c;
+        return str;
+}
+
+int strncmp(const char *str1, const char *str2, size_t n) {
+        return memcmp(str1, str2, n);
+}
+
+int strcmp(const char *str1, const char *str2) {
+        size_t str1_sz = strlen(str1);
+        size_t str2_sz = strlen(str2);
+        if (str1_sz > str2_sz)
+                return memcmp(str1, str2, str2_sz);
+        return memcmp(str1, str2, str1_sz);
+}
+
+size_t strlen(const char *str) {
+        size_t i = 0;
+        while (str[i] != '\0')
+                i++;
+        return i;
+}
+
+int _is_delim(char c, const char *delim) {
+        while (*delim != '\0') {
+                if (c == *delim)
+                        return 1;
+                delim++;
+        }
+        return 0;
+}
+
+char* strtok(char* __restrict str, const char* __restrict delim) {
+        static char *old_str;
+
+        if (str == NULL)
+                str = old_str;
+
+        while (1) {
+                if (_is_delim(*str, delim)) {
+                        str++;
+                        continue;
+                }
+
+                if (*str == '\0')
+                        return NULL;
+                break;
+        }
+
+        char *ret = str;
+        while (1) {
+                if (*str == '\0') {
+                        old_str = str;
+                        return ret;
+                }
+
+                if (_is_delim(*str, delim)) {
+                        *str = '\0';
+                        old_str = str + 1;
+                        return ret;
+                }
+                str++;
+        }
+}
-- 
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