feat: expand user mode, add DOOM game, add manpages

programs/include/libc/string.h

@@ -0,0 +1,35 @@
+#ifndef _LIBC_STRING_H
+#define _LIBC_STRING_H
+
+#pragma once
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void *memcpy(void *dest, const void *src, size_t n);
+void *memset(void *s, int c, size_t n);
+void *memmove(void *dest, const void *src, size_t n);
+int   memcmp(const void *s1, const void *s2, size_t n);
+
+size_t strlen(const char *s);
+int    strcmp(const char *s1, const char *s2);
+int    strncmp(const char *s1, const char *s2, size_t n);
+char  *strcpy(char *dest, const char *src);
+char  *strncpy(char *dest, const char *src, size_t n);
+char  *strcat(char *dest, const char *src);
+char  *strncat(char *dest, const char *src, size_t n);
+char  *strdup(const char *s);
+char  *strchr(const char *s, int c);
+char  *strrchr(const char *s, int c);
+int    strcasecmp(const char *s1, const char *s2);
+int    strncasecmp(const char *s1, const char *s2, size_t n);
+char  *strstr(const char *haystack, const char *needle);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _LIBC_STRING_H */