/*
 * jit-varint.c - Variable length integer encoding.
 *
 * Copyright (C) 2011 Aleksey Demakov
 *
 * The libjit library is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation, either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * The libjit library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with the libjit library. If not, see
 * <http://www.gnu.org/licenses/>.
 */
#include <jit/jit.h>
#include "jit-varint.h"
/*
 * Flush the current encode buffer.
 */
static int
flush_encoder(jit_varint_encoder_t *encoder)
{
	jit_varint_data_t data;
	/* Allocate a new jit_varint_data structure to hold the data */
	data = jit_malloc(sizeof(struct jit_varint_data) + encoder->len);
	if(!data)
	{
		return 0;
	}
	/* Copy the temporary debug data into the new structure */
	jit_memcpy(data->data, encoder->buf, encoder->len);
	/* Link the structure into the debug list */
	data->next = 0;
	if(encoder->last)
	{
		encoder->last->next = data;
	}
	else
	{
		encoder->data = data;
	}
	encoder->last = data;
	/* Reset the temporary debug buffer */
	encoder->len = 0;
	return 1;
}
void
_jit_varint_init_encoder(jit_varint_encoder_t *encoder)
{
	encoder->len = 0;
	encoder->data = 0;
	encoder->last = 0;
}
void
_jit_varint_init_decoder(jit_varint_decoder_t *decoder, jit_varint_data_t data)
{
	decoder->len = 0;
	decoder->data = data;
	decoder->end = (data == 0);
}
int
_jit_varint_encode_end(jit_varint_encoder_t *encoder)
{
	if(!encoder->len)
	{
		return 1;
	}
	/* Mark the end of the data */
	encoder->buf[encoder->len++] = 0xFF;
	/* Flush the data that we have collected so far */
	return flush_encoder(encoder);
}
/*
 * Compress a "long" value so that it takes up less bytes.
 * This is used to store offsets within functions and
 * debug line numbers, which are usually small integers.
 */
int
_jit_varint_encode_uint(jit_varint_encoder_t *encoder, jit_uint value)
{
	if(encoder->len + 6> sizeof(encoder->buf))
	{
		/* Overflow occurred: end current buffer */
		if(!_jit_varint_encode_end(encoder))
		{
			return 0;
		}
	}
	/* Write the value to the temporary buffer */
	if(value < 0x80) { /* 0xxx xxxx */ encoder->buf[encoder->len++] = (unsigned char) (value);
	}
	else if(value < 0x4000) { /* 10xx xxxx &#124; xxxx xxxx */ encoder->buf[encoder->len++] = (unsigned char) (value>> 8) &#124; 0x80;
		encoder->buf[encoder->len++] = (unsigned char) (value);
	}
	else if(value < 0x200000) { /* 110x xxxx &#124; xxxx xxxx &#124; xxxx xxxx */ encoder->buf[encoder->len++] = (unsigned char) (value>> 16) &#124; 0xC0;
		encoder->buf[encoder->len++] = (unsigned char) (value>> 8);
		encoder->buf[encoder->len++] = (unsigned char) (value);
	}
	else if(value < 0x10000000) { /* 1110 xxxx &#124; xxxx xxxx &#124; xxxx xxxx &#124; xxxx xxxx */ encoder->buf[encoder->len++] = (unsigned char) (value>> 24) &#124; 0xE0;
		encoder->buf[encoder->len++] = (unsigned char) (value>> 16);
		encoder->buf[encoder->len++] = (unsigned char) (value>> 8);
		encoder->buf[encoder->len++] = (unsigned char) (value);
	}
	else
	{
		/* 1111 0000 &#124; xxxx xxxx &#124; xxxx xxxx &#124; xxxx xxxx &#124; xxxx xxxx */
		encoder->buf[encoder->len++] = 0xF0;
		encoder->buf[encoder->len++] = (unsigned char) (value>> 24);
		encoder->buf[encoder->len++] = (unsigned char) (value>> 16);
		encoder->buf[encoder->len++] = (unsigned char) (value>> 8);
		encoder->buf[encoder->len++] = (unsigned char) (value);
	}
	return 1;
}
jit_varint_data_t
_jit_varint_get_data(jit_varint_encoder_t *encoder)
{
	return encoder->data;
}
void
_jit_varint_free_data(jit_varint_data_t data)
{
	while(data)
	{
		jit_varint_data_t next = data->next;
		jit_free(data);
		data = next;
	}
}
int
_jit_varint_decode_end(jit_varint_decoder_t *decoder)
{
	return decoder->end;
}
jit_uint
_jit_varint_decode_uint(jit_varint_decoder_t *decoder)
{
	jit_uint value;
	unsigned char c;
	value = (jit_uint) (-1);
	if(decoder->end)
	{
		return value;
	}
	if(decoder->len>= JIT_VARINT_BUFFER_SIZE)
	{
		/* Sanity check failed */
		decoder->end = 2;
		return value;
	}
again:
	c = decoder->data->data[decoder->len++];
	if(!(c & 0x80))
	{
		/* 0xxx xxxx */
		value = ((jit_uint) c);
	}
	else if(!(c & 0x40))
	{
		/* 10xx xxxx &#124; xxxx xxxx */
		value = ((jit_uint) c & 0x3F) << 8; value &#124;= ((jit_uint) decoder->data->data[decoder->len++]);
	}
	else if(!(c & 0x20))
	{
		/* 110x xxxx &#124; xxxx xxxx &#124; xxxx xxxx */
		value = ((jit_uint) c & 0x1F) << 16; value &#124;= ((jit_uint) decoder->data->data[decoder->len++]) << 8; value &#124;= ((jit_uint) decoder->data->data[decoder->len++]);
	}
	else if(!(c & 0x10))
	{
		/* 1110 xxxx &#124; xxxx xxxx &#124; xxxx xxxx &#124; xxxx xxxx */
		value = ((jit_uint) c & 0x0F) << 24; value &#124;= ((jit_uint) decoder->data->data[decoder->len++]) << 16; value &#124;= ((jit_uint) decoder->data->data[decoder->len++]) << 8; value &#124;= ((jit_uint) decoder->data->data[decoder->len++]);
	}
	else if(!(c & 0x0f))
	{
		/* 1111 0000 &#124; xxxx xxxx &#124; xxxx xxxx &#124; xxxx xxxx &#124; xxxx xxxx */
		value &#124;= ((jit_uint) decoder->data->data[decoder->len++]) << 24; value &#124;= ((jit_uint) decoder->data->data[decoder->len++]) << 16; value &#124;= ((jit_uint) decoder->data->data[decoder->len++]) << 8; value &#124;= ((jit_uint) decoder->data->data[decoder->len++]);
	}
	else
	{
		/* Met data end mark */
		if(decoder->data->next)
		{
			/* There is another data block */
			decoder->data = decoder->data->next;
			decoder->len = 0;
			goto again;
		}
		/* This was the last data block */
		decoder->end = 1;
	}
	return value;
}
#if 0
void
_jit_varint_encode_int(jit_varint_encoder_t *encoder, jit_int value)
{
	value = (value << 1) ^ (value>> (8 * sizeof(jit_uint) - 1));;
	_jit_varint_encode_uint(encoder, (jit_uint) value);
}
jit_int
_jit_varint_decode_int(jit_varint_decoder_t *decoder)
{
	jit_uint value = _jit_varint_decode_uint(decoder);
	return (jit_int) ((value>> 1) ^ -(value & 1));
}
#endif
#if defined(VARINT_TEST)
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void *
jit_malloc(unsigned int size)
{
	return malloc(size);
}
void
jit_free(void *ptr)
{
	if(ptr)
	{
		free(ptr);
	}
}
void *
jit_memcpy(void *dest, const void *src, unsigned int len)
{
	return memcpy(dest, src, len);
}
int
main()
{
	jit_uint i, j, n, v;
	for(n = 1; n != 0; n>>= 1)
	{
		jit_varint_encoder_t encoder;
		_jit_varint_init_encoder(&encoder);
		_jit_varint_encode_uint(&encoder, n);
		_jit_varint_encode_uint(&encoder, n - 1);
		_jit_varint_encode_uint(&encoder, n + 1);
		_jit_varint_encode_end(&encoder);
		jit_varint_data_t data = _jit_varint_get_data(&encoder);
		jit_varint_decoder_t decoder;
		_jit_varint_init_decoder(&decoder, data);
		v = _jit_varint_decode_uint(&decoder);
		if(v != n)
		{
			fprintf(stderr, "FAILED\n");
		}
		v = _jit_varint_decode_uint(&decoder);
		if(v != n - 1)
		{
			fprintf(stderr, "FAILED\n");
		}
		v = _jit_varint_decode_uint(&decoder);
		if(v != n + 1)
		{
			fprintf(stderr, "FAILED\n");
		}
		_jit_varint_decode_uint(&decoder);
		if(!_jit_varint_decode_end(&decoder))
		{
			fprintf(stderr, "FAILED\n");
		}
		_jit_varint_free_data(data);
	}
}
#endif
</div><div class="naked_ctrl">
<form action="/index.cgi/contrast" method="get" name="gate">
<p><a href="http://altstyle.alfasado.net">AltStyle</a> によって変換されたページ <a href="https://cgit.git.savannah.gnu.org/cgit/libjit.git/plain/jit/jit-varint.c">(-&gt;オリジナル)</a>
/ <label>アドレス: <input type="text" name="naked_post_url" value="https://cgit.git.savannah.gnu.org/cgit/libjit.git/plain/jit/jit-varint.c" size="22" /></label> <label>モード: <select name="naked_post_mode">
<option value="default">デフォルト</option>
<option value="speech">音声ブラウザ</option>
<option value="ruby">ルビ付き</option>
<option value="contrast" selected="selected">配色反転</option>
<option value="larger-text">文字拡大</option>
<option value="mobile">モバイル</option>
</select>
<input type="submit" value="表示" />
</p>
</form>
</div>