libc: add string operations for libc

lib/c/CMakeLists.txt

@@ -0,0 +1,21 @@
+# See the end of this file for copyright and license terms.
+
+add_library(c)
+target_include_directories(c PRIVATE ${GAY_INCLUDE_DIRS})
+target_compile_definitions(c PRIVATE ${GAY_DEFINITIONS})
+
+target_sources(c PRIVATE
+    string.c
+)
+
+# This file is part of GayBSD.
+# Copyright (c) 2021 fef <owo@fef.moe>.
+#
+# GayBSD is nonviolent software: you may only use, redistribute, and/or
+# modify it under the terms of the Cooperative Nonviolent Public License
+# (CNPL) as found in the LICENSE file in the source code root directory
+# or at <https://git.pixie.town/thufie/npl-builder>; either version 7
+# of the license, or (at your option) any later version.
+#
+# GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
+# permitted by applicable law.  See the CNPL for details.

lib/c/string.c

@@ -0,0 +1,127 @@
+/* See the end of this file for copyright and license terms. */
+
+#include <gay/types.h>
+
+#include <string.h>
+
+int memcmp(const void *s1, const void *s2, size_t n)
+{
+	int delta = 0;
+
+	while (n-- > 0) {
+		/* POSIX explicitly wants a cast to unsigned char */
+		delta = *(const unsigned char *)s1++ - *(const unsigned char *)s2++;
+		if (delta != 0)
+			break;
+	}
+
+	return delta;
+}
+
+void *memcpy(void *dest, const void *src, size_t n)
+{
+	u8 *tmp = (u8 *)dest;
+
+	while (n-- > 0)
+		*tmp++ = *(const u8 *)src++;
+
+	return dest;
+}
+
+void *memset(void *ptr, int c, size_t n)
+{
+	char *tmp = (char *)ptr;
+
+	while (n-- > 0)
+		*tmp++ = (char)c;
+
+	return ptr;
+}
+
+void *memmove(void *dest, const void *src, size_t n)
+{
+	char *tmp = (char *)dest;
+	const char *s = (const char *)src;
+
+	if (dest == src)
+		return dest;
+
+	if (dest < src) {
+		while (n-- != 0)
+			*tmp++ = *s++;
+	} else {
+		tmp += n;
+		s += n;
+		while (n-- != 0)
+			*--tmp = *--s;
+	}
+
+	return dest;
+}
+
+int strcmp(const char *s1, const char *s2)
+{
+	while (*s1 == *s2) {
+		if (*s1++ == '\0' || *s2++ == '\0')
+			break;
+	}
+
+	/* POSIX explicitly wants a cast to unsigned char */
+	return *((const unsigned char *)s1) - *((const unsigned char *)s2);
+}
+
+char *strcpy(char *dest, const char *src)
+{
+	char *tmp = dest;
+
+	while ((*tmp++ = *src++) != '\0');
+		/* nothing */
+
+	return dest;
+}
+
+char *strncpy(char *dest, const char *src, size_t n)
+{
+	char *tmp = dest;
+
+	while (n-- != 0) {
+		if ((*tmp++ = *src++) == '\0')
+			break;
+	}
+
+	return dest;
+}
+
+size_t strlen(const char *s)
+{
+	const char *tmp = s;
+
+	while (*tmp++ != '\0');
+		/* nothing */
+
+	return (size_t)tmp - (size_t)s - 1;
+}
+
+size_t strnlen(const char *s, size_t maxlen)
+{
+	const char *tmp = s;
+
+	while (*tmp++ != '\0' && maxlen-- > 0);
+		/* nothing */
+
+	return (size_t)tmp - (size_t)s - 1;
+}
+
+/*
+ * This file is part of GayBSD.
+ * Copyright (c) 2021 fef <owo@fef.moe>.
+ *
+ * GayBSD is nonviolent software: you may only use, redistribute, and/or
+ * modify it under the terms of the Cooperative Nonviolent Public License
+ * (CNPL) as found in the LICENSE file in the source code root directory
+ * or at <https://git.pixie.town/thufie/npl-builder>; either version 7
+ * of the license, or (at your option) any later version.
+ *
+ * GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
+ * permitted by applicable law.  See the CNPL for details.
+ */