[*] Initial commit

lonetix/numlib_itoa.c

@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+/**
+ * \file numlib_itoa.c
+ *
+ * Integer to ASCII conversion.
+ *
+ * \copyright The DoubleFourteen Code Forge (C) All Rights Reserved
+ * \author    Lorenzo Cogotti
+ */
+
+#include "numlib.h"
+
+#include <string.h>
+
+// XXX(micia): benchmark memcpy()-less version, something with rep stos
+//             amount of data copied over is very small, so it would probably pay off
+//             leaving memcpy() out
+
+char *Utoa(unsigned long long x, char *dest)
+{
+	char buf[DIGS(x) + 1];
+	size_t n;
+
+	char *p = buf + sizeof(buf);
+
+	*--p = '\0';
+	do {
+		*--p  = '0' + (x % 10);
+		x    /= 10;
+	} while (x != 0);
+
+	n = (buf + sizeof(buf)) - p;
+	memcpy(dest, p, n);
+	return dest + n - 1;
+}
+
+char *Itoa(long long x, char *dest)
+{
+	char buf[1 + DIGS(x) + 1];
+	unsigned long long ax;  // NOTE keep this unsigned!
+	size_t n;
+
+	char *p = buf + sizeof(buf);
+
+	ax = ABS(x);  // also handles LLONG_MIN, ax being unsigned
+	              // NOTE: this is still a signed overflow, which is technically
+	              //       undefined in standard C
+
+	*--p = '\0';
+	do {
+		*--p  = '0' + (ax % 10);
+		ax   /= 10;
+	} while (ax != 0);
+
+	if (x < 0)
+		*--p = '-';
+
+	n = (buf + sizeof(buf)) - p;
+	memcpy(dest, p, n);
+	return dest + n - 1;
+}
+
+char *Xtoa(unsigned long long x, char *dest)
+{
+	char buf[XDIGS(x) + 1];
+	size_t n;
+
+	char *p = buf + sizeof(buf);
+
+	*--p = '\0';
+	do {
+		*--p   = "0123456789abcdef"[x & 0xf];
+		x    >>= 4;
+	} while (x != 0);
+
+	n = (buf + sizeof(buf)) - p;
+	memcpy(dest, p, n);
+	return dest + n - 1;
+}