/*
* Copyright (c) 2011 Bryan O'Sullivan <bos@serpentine.com>.
*
* Portions copyright (c) 2008-2010 Björn Höhrmann <bjoern@hoehrmann.de>.
*
* See http://bjoern.hoehrmann.de/utf-8/decoder/dfa/ for details.
*/
#include <string.h>
#include <stdint.h>
#include <stdio.h>
#include "pipes_text_cbits.h"
#define UTF8_ACCEPT 0
#define UTF8_REJECT 12
static const uint8_t utf8d[] = {
/*
* The first part of the table maps bytes to character classes that
* to reduce the size of the transition table and create bitmasks.
*/
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
8,8,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
10,3,3,3,3,3,3,3,3,3,3,3,3,4,3,3, 11,6,6,6,5,8,8,8,8,8,8,8,8,8,8,8,
/*
* The second part is a transition table that maps a combination of
* a state of the automaton and a character class to a state.
*/
0,12,24,36,60,96,84,12,12,12,48,72, 12,12,12,12,12,12,12,12,12,12,12,12,
12, 0,12,12,12,12,12, 0,12, 0,12,12, 12,24,12,12,12,12,12,24,12,24,12,12,
12,12,12,12,12,12,12,24,12,12,12,12, 12,24,12,12,12,12,12,12,12,24,12,12,
12,12,12,12,12,12,12,36,12,36,12,12, 12,36,12,12,12,12,12,36,12,36,12,12,
12,36,12,12,12,12,12,12,12,12,12,12,
};
static inline uint32_t
decode(uint32_t *state, uint32_t* codep, uint32_t byte) {
uint32_t type = utf8d[byte];
*codep = (*state != UTF8_ACCEPT) ?
(byte & 0x3fu) | (*codep << 6) :
(0xff >> type) & (byte);
return *state = utf8d[256 + *state + type];
}
/*
* A best-effort decoder. Runs until it hits either end of input or
* the start of an invalid byte sequence.
*
* At exit, we update *destoff with the next offset to write to, *src
* with the next source location past the last one successfully
* decoded, and return the next source location to read from.
*
* Moreover, we expose the internal decoder state (state0 and
* codepoint0), allowing one to restart the decoder after it
* terminates (say, due to a partial codepoint).
*
* In particular, there are a few possible outcomes,
*
* 1) We decoded the buffer entirely:
* In this case we return srcend
* state0 == UTF8_ACCEPT
*
* 2) We met an invalid encoding
* In this case we return the address of the first invalid byte
* state0 == UTF8_REJECT
*
* 3) We reached the end of the buffer while decoding a codepoint
* In this case we return a pointer to the first byte of the partial codepoint
* state0 != UTF8_ACCEPT, UTF8_REJECT
*
*/
const uint8_t *
_hs_pipes_text_decode_utf8_state(uint16_t *const dest, size_t *destoff,
const uint8_t **const src,
const uint8_t *const srcend,
uint32_t *codepoint0, uint32_t *state0)
{
uint16_t *d = dest + *destoff;
const uint8_t *s = *src, *last = *src;
uint32_t state = *state0;
uint32_t codepoint = *codepoint0;
while (s < srcend) {
#if defined(__i386__) || defined(__x86_64__)
/*
* This code will only work on a little-endian system that
* supports unaligned loads.
*
* It gives a substantial speed win on data that is purely or
* partly ASCII (e.g. HTML), at only a slight cost on purely
* non-ASCII text.
*/
if (state == UTF8_ACCEPT) {
while (s < srcend - 4) {
codepoint = *((uint32_t *) s);
if ((codepoint & 0x80808080) != 0)
break;
s += 4;
/*
* Tried 32-bit stores here, but the extra bit-twiddling
* slowed the code down.
*/
*d++ = (uint16_t) (codepoint & 0xff);
*d++ = (uint16_t) ((codepoint >> 8) & 0xff);
*d++ = (uint16_t) ((codepoint >> 16) & 0xff);
*d++ = (uint16_t) ((codepoint >> 24) & 0xff);
}
last = s;
}
#endif
if (decode(&state, &codepoint, *s++) != UTF8_ACCEPT) {
if (state != UTF8_REJECT)
continue;
break;
}
if (codepoint <= 0xffff)
*d++ = (uint16_t) codepoint;
else {
*d++ = (uint16_t) (0xD7C0 + (codepoint >> 10));
*d++ = (uint16_t) (0xDC00 + (codepoint & 0x3FF));
}
last = s;
}
/* Invalid encoding, back up to the errant character */
if (state == UTF8_REJECT)
s -= 1;
*destoff = d - dest;
*codepoint0 = codepoint;
*state0 = state;
*src = last;
return s;
}
