Add stupid string.h implementation

lib/string.c

@@ -0,0 +1,150 @@
+/*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted
+ * provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of
+ *    conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
+ *    conditions and the following disclaimer in the documentation and/or other materials
+ *    provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software without specific prior
+ *    written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
+ * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <ardix/string.h>
+#include <ardix/types.h>
+
+#ifndef __HAVE_ASM_MEMCMP
+int memcmp(const void *s1, const void *s2, size_t n)
+{
+	int delta = 0;
+
+	while (n-- > 0) {
+		/*
+		 * TODO
+		 * See if avr-gcc is smart enough to combine the pointer
+		 * dereferencing and increment into a single `ld Rd,X+`
+		 * instruction even if there is an if statement in between
+		 */
+		delta = *(const unsigned char *)s1 - *(const unsigned char *)s2;
+		if (delta != 0)
+			break;
+
+		s1++;
+		s2++;
+	}
+
+	return delta;
+}
+#endif /* __HAVE_ASM_MEMCMP */
+
+#ifndef __HAVE_ASM_MEMCPY
+void *memcpy(void *dest, const void *src, size_t n)
+{
+	uint8_t *tmp = (uint8_t *)dest;
+
+	while (n-- > 0)
+		*tmp++ = *(const uint8_t *)src++;
+
+	return dest;
+}
+#endif /* __HAVE_ASM_MEMCPY */
+
+#ifndef __HAVE_ASM_MEMSET
+void *memset(void *ptr, int c, size_t n)
+{
+	char *tmp = (char *)ptr;
+
+	while (n-- > 0)
+		*tmp++ = (char)c;
+
+	return ptr;
+}
+#endif /* __HAVE_ASM_MEMSET */
+
+#ifndef __HAVE_ASM_MEMMOVE
+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;
+}
+#endif /* __HAVE_ASM_MEMMOVE */
+
+#ifndef __HAVE_ASM_STRCMP
+int strcmp(const char *s1, const char *s2)
+{
+	while (*s1++ == *s2++) {
+		if (*s1 == '\0' || *s2 == '\0')
+			break;
+	}
+
+	return *((const unsigned char *)s1) - *((const unsigned char *)s2);
+}
+#endif /* __HAVE_ASM_STRCMP */
+
+#ifndef __HAVE_ASM_STRCPY
+char *strcpy(char *dest, const char *src)
+{
+	char *tmp = dest;
+
+	while ((*tmp++ = *src++) != '\0');
+		/* nothing */
+
+	return dest;
+}
+#endif /* __HAVE_ASM_STRCPY */
+
+#ifndef __HAVE_ASM_STRNCPY
+char *strncpy(char *dest, const char *src, size_t n)
+{
+	char *tmp = dest;
+
+	while (n-- != 0) {
+		if ((*tmp++ = *src++) == '\0')
+			break;
+	}
+
+	return dest;
+}
+#endif /* __HAVE_ASM_STRNCPY */
+
+#ifndef __HAVE_ASM_STRLEN
+size_t strlen(const char *s)
+{
+	const char *tmp = s;
+
+	while (*tmp++ != '\0');
+		/* nothing */
+
+	return (size_t)tmp - (size_t)s - (size_t)1;
+}
+#endif /* __HAVE_ASM_STRLEN */