mkp224o/base32_from.c

#include <stddef.h>
#include <stdint.h>
#include "types.h"
#include "base32.h"

static const u8 base32f[256] = {
	//00    01    02    03    04    05    06    07
	//08    09    0A    0B    0C    0D    0E    0F
	// 0x00..0x3F
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x00
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x08
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x10
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x18
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x20
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x28
	0xFF, 0xFF, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, // 0x30
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x38
	// 0x40..0x7F
	0xFF, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, // 0x40
	0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, // 0x48
	0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, // 0x50
	0x17, 0x18, 0x19, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x58
	0xFF, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, // 0x60
	0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, // 0x68
	0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, // 0x70
	0x17, 0x18, 0x19, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x78
	// 0x80..0xBF
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	// 0xC0..0xFF
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
};
/*
+--first octet--+-second octet--+--third octet--+--forth octet--+--fifth octet--+
|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|7 6 5 4 3 2 1 0|
+---------+-----+---+---------+-+-------+-------+-+---------+---+-----+---------+
|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|4 3 2 1 0|
+-1.index-+-2.index-+-3.index-+-4.index-+-5.index-+-6.index-+-7.index-+-8.index-+
*/
size_t base32_from(u8 *dst,u8 *dmask,const char *src)
{
	size_t i, j, k = (size_t)-1, l, sk = 0;
	u8 mask = 0, cmask = 0;
	for (i = 0;;i += 5) {
		j = i/5;
		if (!src[j]) {
			if (k != (size_t)-1)
				dst[k] &= cmask;
			if (dmask)
				*dmask = cmask;
			return k + 1;
		}
		l = i%8;
		k = i/8;
		if (k != sk)
			cmask = 0;
		sk = k;
		mask = (0x1F << 3) >> l;
		cmask |= mask;
		//printf("1:m[%02X] cm[%02X]\n",mask,cmask);
		dst[k] &= ~mask;
		dst[k] |= (base32f[(u8)src[j]] << 3) >> l;
		if (((0x1F << 8) >> (l+5-8)) & 0xFF) {
			++k;
			sk = k;
			mask = ((0x1F << 8) >> (l+5-8)) & 0xFF;
			cmask = mask;
			//printf("2:m[%02X] cm[%02X]\n",mask,cmask);
			dst[k] &= ~mask;
			dst[k] |= ((base32f[(u8)src[j]] << 8) >> (l+5-8)) & 0xFF;
		}
		//printf("i = %02d, i/8 = %02d, i%8 = %02d, i%8+5-8 = %02d\n", i, i/8, i%8, i%8+5-8);
		//printf("mask0: %02x\n", (0x1F << 3) >> (i%8));
		//printf("mask1: %02x\n", ((0x1F << 8) >> (i%8+5-8)) & 0xFF);
	}
}

int base32_valid(const char *src,size_t *count)
{
	const char *p;

	for (p = src;base32f[(u8)*p] != 0xFF;++p)
		;

	if (count)
		*count = (size_t) (p - src);
	return !*p;
}