pecanpico9/tracker/software/math/base128.c

120 wiersze
3.4 KiB
C

#include <stdint.h>
#define PADCHAR '!'
#define INBYTES 7
#define OUTBYTES 8
#define ZOF_TAB 256
#define BAD 0xFF
#define PAD 0xFE /* Encoded '!' is padding */
static const unsigned char dtab[ZOF_TAB] =
{
BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, 187, BAD, 188, BAD, BAD, BAD, BAD,
BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, 189, 190, BAD, BAD, BAD,
191, PAD, BAD, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,
29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44,
45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, BAD, 57, 58, 59,
60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75,
76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, BAD,
BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD,
BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD,
91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106,
107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122,
123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138,
139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154,
155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170,
171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186,
};
static const char *etab = "#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_`abcdefghijklmnopqrstuvwxyz{|}~"
"\xA0\xA1\xA2\xA3\xA4\xA5\xA6\xA7\xA8\xA9\xAA\xAB\xAC\xAD\xAE\xAF\xB0\xB1\xB2\xB3\xB4\xB5\xB6\xB7\xB8\xB9\xBA\xBB\xBC\xBD\xBE\xBF"
"\xC0\xC1\xC2\xC3\xC4\xC5\xC6\xC7\xC8\xC9\xCA\xCB\xCC\xCD\xCE\xCF\xD0\xD1\xD2\xD3\xD4\xD5\xD6\xD7\xD8\xD9\xDA\xDB\xDC\xDD\xDE\xDF"
"\xE0\xE1\xE2\xE3\xE4\xE5\xE6\xE7\xE8\xE9\xEA\xEB\xEC\xED\xEE\xEF\xF0\xF1\xF2\xF3\xF4\xF5\xF6\xF7\xF8\xF9\xFA\xFB\xFC\xFD\xFE\xFF"
"\t\x0B\x1B\x1C ";
uint32_t b128_encode(uint8_t *infile, uint8_t *outfile, uint32_t input_length)
{
unsigned char in[INBYTES];
unsigned char topbits, mask;
int i, len;
uint32_t k = 0;
uint32_t j = 0;
while(k < input_length)
{
len = 0;
for (i = 0; i < INBYTES; i++)
{
in[i] = infile[k++];
len++;
if (k >= input_length) {
break;
}
}
if (len > 0)
{
topbits = 0;
mask = 0x40;
for (i = 0; i < len; i++)
{
outfile[j++] = etab[in[i] & 0x7F];
if (in[i] > 0x7F)
topbits |= mask;
mask >>= 1;
}
if (len < INBYTES) /* Need to pad */
{
outfile[j++] = PADCHAR;
}
outfile[j++] = etab[topbits];
}
}
outfile[j] = 0;
return j;
}
uint32_t b128_decode(uint8_t *infile, uint8_t *outfile, uint32_t input_length)
{
unsigned char in[OUTBYTES];
unsigned char topbits, mask;
int i, len;
uint32_t k = 0;
uint32_t j = 0;
while(k < input_length)
{
len = 0;
for (i = 0; i < OUTBYTES; i++)
{
in[i] = infile[k++];
len++;
if (k >= input_length)
break;
}
if (len > 0)
{
topbits = dtab[in[len - 1]];
mask = 0x40;
for (len = i = 0; i < INBYTES; i++)
{
if (in[i] == PADCHAR)
break;
len++;
in[i] = dtab[in[i]];
if (in[i] == BAD) /* Illegal encoding character, bail out */
return 0;
if (topbits & mask)
in[i] |= 0x80;
mask >>= 1;
}
for (i = 0; i < len; i++)
{
outfile[j++] = in[i];
}
}
}
return j;
}