Bug#627899: Acknowledgement (avr-libc itoa & ltoa & ultoa can be realized more fast)

[Dmitry E. Oboukhov]

In attache there is a file that can convert using the algorithm for 8,
16, 32, 36 and 10 (default) radixes.

-- 

. ''`.                               Dmitry E. Oboukhov
: :’  :   email: un...@debian.org jabber://un...@uvw.ru
`. `~’              GPGKey: 1024D / F8E26537 2006-11-21
  `- 1B23 D4F8 8EC0 D902 0555  E438 AB8C 00CF F8E2 6537

#include <avr/pgmspace.h>

static const unsigned long digits8[] PROGMEM = {
	1073741824,
	134217728,
	16777216,
	2097152,
	262144,
	32768,
	4096,
	512,
	64,
	8,
	1,
};

static const unsigned long digits10[] PROGMEM = {
	1000000000,
	100000000,
	10000000,
	1000000,
	100000,
	10000,
	1000,
	100,
	10,
	1,
};

static const unsigned long digits16[] PROGMEM = {
	268435456,
	16777216,
	1048576,
	65536,
	4096,
	256,
	16,
	1,
};

static const unsigned long digits32[] PROGMEM = {
	1073741824,
	33554432,
	1048576,
	32768,
	1024,
	32,
	1,
};

static const unsigned long digits36[] PROGMEM = {
	2176782336,
	60466176,
	1679616,
	46656,
	1296,
	36,
	1,
};

static const char *letters PROGMEM =
	"0123456789"
	"abcdefghijklmnopqrstuvwxyz";

char *	my_ultoa (unsigned long __val, char *__s, int base) {
	unsigned char max;
	const unsigned long *d;
	unsigned char i, j, k, first = 1;

	switch(base) {
		case 8:
			max = sizeof(digits8) / sizeof(unsigned long);
			d = digits8;
			break;

		case 16:
			max = sizeof(digits16) / sizeof(unsigned long);
			d = digits16;
			break;

		case 32:
			max = sizeof(digits32) / sizeof(unsigned long);
			d = digits32;
			break;

		case 36:
			max = sizeof(digits36) / sizeof(unsigned long);
			d = digits36;
			break;

		default:
			max = sizeof(digits10) / sizeof(unsigned long);
			d = digits10;
			break;
	}

	for (i = j = 0; i < max; i++) {
		unsigned long check = pgm_read_dword(d + i);
		if (check > __val) {
			if (first)
				continue;
			__s[j++] = '0';
			continue;
		}
		first = k = 0;
		while(check <= __val) {
			__val -= check;
			k++;
		}

		__s[j++] = pgm_read_byte(letters + k);
	}

	if (first)
		__s[j++] = '0';
	__s[j] = 0;

	return __s;
}

char * my_ltoa (long __val, char *__s, int base) {
	if (__val >= 0)
		return my_ultoa((unsigned long)__val, __s, base);
	__s[0] = '-';
	return my_ultoa((unsigned long)(-__val), __s + 1, base) - 1;
}

signature.asc
Description: Digital signature