reorganization: first steps

1 files changed, 82 insertions, 0 deletions

diff --git a/src/libk/mem.c b/src/libk/mem.c
new file mode 100644
index 0000000..14dd6bd
--- /dev/null
+++ b/src/libk/mem.c
@@ -0,0 +1,82 @@
+#include <assert.h>
+#include <shared/mem.h>
+#include <stdint.h>
+
+union dualptr_const { const uintptr_t *w; const char *c; uintptr_t u; };
+union dualptr       {       uintptr_t *w;       char *c; uintptr_t u; };
+
+void *memchr(const void *s, int c, size_t n) {
+	const unsigned char *s2 = s;
+	for (size_t i = 0; i < n; i++) {
+		if (s2[i] == (unsigned char)c)
+			return (void*)&s2[i];
+	}
+	return NULL;
+}
+
+int memcmp(const void *s1, const void *s2, size_t n) {
+	const unsigned char *c1 = s1, *c2 = s2;
+	for (size_t i = 0; i < n; i++) {
+		if (c1[i] != c2[i]) {
+			if (c1[i] < c2[i])  return -1;
+			else                return 1;
+		}
+	}
+	return 0;
+}
+
+void *memcpy(void *dest, const void *src, size_t n) {
+	// TODO erms, rep movsb
+	union dualptr_const s = {.c = src};
+	union dualptr d = {.c = dest};
+	if (dest == src) return dest;
+	// assert(src >= dest || src + n < dest);
+
+	for (; (d.u & 7) && n != 0; n--) {
+		*(d.c)++ = *(s.c)++;
+	}
+	while (n >= sizeof(uintptr_t)) {
+		*(d.w)++ = *(s.w)++;
+		n -= sizeof(uintptr_t);
+	}
+	while (n-- != 0) {
+		*(d.c)++ = *(s.c)++;
+	}
+	return dest;
+}
+
+void *memmove(void *dest, const void *src, size_t n) {
+	if (src >= dest || src + n < dest)
+		return memcpy(dest, src, n);
+	for (; n; n--) /* naive reverse copy */
+		((uint8_t*)dest)[n-1] = ((uint8_t*)src)[n-1];
+	return dest;
+}
+
+void *memset(void *s, int c, size_t n) {
+	union dualptr d = {.c = s};
+
+	uintptr_t fill = (c & 0xff) * 0x0101010101010101;
+	while (n >= sizeof(uintptr_t)) {
+		*(d.w)++ = fill;
+		n -= sizeof(uintptr_t);
+	}
+	while (n-- != 0)
+		*(d.c)++ = c;
+	return s;
+}
+
+int strcmp(const char *s1, const char *s2) {
+	while (*s1 && *s1 == *s2) {
+		s1++; s2++;
+	}
+	if (*s1 == *s2) return  0;
+	if (*s1 <  *s2) return -1;
+	else            return  1;
+}
+
+size_t strlen(const char *s) {
+	size_t c = 0;
+	while (*s++) c++;
+	return c;
+}