Head

GCC Code Coverage Report

Directory:	../../../ffmpeg/		Exec	Total	Coverage
File:	src/libavcodec/lzwenc.c	Lines:	86	88	97.7 %
Date:	2020-01-28 04:56:05	Branches:	30	36	83.3 %


/*
 * LZW encoder
 * Copyright (c) 2007 Bartlomiej Wolowiec
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * LZW encoder
 * @author Bartlomiej Wolowiec
 */

#include "avcodec.h"
#include "lzw.h"
#include "mathops.h"
#include "put_bits.h"

#define LZW_MAXBITS 12
#define LZW_SIZTABLE (1<<LZW_MAXBITS)
#define LZW_HASH_SIZE 16411
#define LZW_HASH_SHIFT 6

#define LZW_PREFIX_EMPTY -1
#define LZW_PREFIX_FREE -2

/** One code in hash table */
typedef struct Code{
    /// Hash code of prefix, LZW_PREFIX_EMPTY if empty prefix, or LZW_PREFIX_FREE if no code
    int hash_prefix;
    int code;               ///< LZW code
    uint8_t suffix;         ///< Last character in code block
}Code;

/** LZW encode state */
typedef struct LZWEncodeState {
    int clear_code;          ///< Value of clear code
    int end_code;            ///< Value of end code
    Code tab[LZW_HASH_SIZE]; ///< Hash table
    int tabsize;             ///< Number of values in hash table
    int bits;                ///< Actual bits code
    int bufsize;             ///< Size of output buffer
    PutBitContext pb;        ///< Put bit context for output
    int maxbits;             ///< Max bits code
    int maxcode;             ///< Max value of code
    int output_bytes;        ///< Number of written bytes
    int last_code;           ///< Value of last output code or LZW_PREFIX_EMPTY
    enum FF_LZW_MODES mode;  ///< TIFF or GIF
    void (*put_bits)(PutBitContext *, int, unsigned); ///< GIF is LE while TIFF is BE
}LZWEncodeState;


const int ff_lzw_encode_state_size = sizeof(LZWEncodeState);

/**
 * Hash function adding character
 * @param head LZW code for prefix
 * @param add Character to add
 * @return New hash value
 */
static inline int hash(int head, const int add)
{
    head ^= (add << LZW_HASH_SHIFT);
    if (head >= LZW_HASH_SIZE)
        head -= LZW_HASH_SIZE;
    av_assert2(head >= 0 && head < LZW_HASH_SIZE);
    return head;
}

/**
 * Hash function calculates next hash value
 * @param head Actual hash code
 * @param offset Offset calculated by hashOffset
 * @return New hash value
 */
static inline int hashNext(int head, const int offset)
{
    head -= offset;
    if(head < 0)
        head += LZW_HASH_SIZE;
    return head;
}

/**
 * Hash function calculates hash offset
 * @param head Actual hash code
 * @return Hash offset
 */
static inline int hashOffset(const int head)
{
    return head ? LZW_HASH_SIZE - head : 1;
}

/**
 * Write one code to stream
 * @param s LZW state
 * @param c code to write
 */
static inline void writeCode(LZWEncodeState * s, int c)
{
    av_assert2(0 <= c && c < 1 << s->bits);
    s->put_bits(&s->pb, s->bits, c);
}


/**
 * Find LZW code for block
 * @param s LZW state
 * @param c Last character in block
 * @param hash_prefix LZW code for prefix
 * @return LZW code for block or -1 if not found in table
 */
static inline int findCode(LZWEncodeState * s, uint8_t c, int hash_prefix)
{
    int h = hash(FFMAX(hash_prefix, 0), c);
    int hash_offset = hashOffset(h);

    while (s->tab[h].hash_prefix != LZW_PREFIX_FREE) {
        if ((s->tab[h].suffix == c)
            && (s->tab[h].hash_prefix == hash_prefix))
            return h;
        h = hashNext(h, hash_offset);
    }

    return h;
}

/**
 * Add block to LZW code table
 * @param s LZW state
 * @param c Last character in block
 * @param hash_prefix LZW code for prefix
 * @param hash_code LZW code for bytes block
 */
static inline void addCode(LZWEncodeState * s, uint8_t c, int hash_prefix, int hash_code)
{
    s->tab[hash_code].code = s->tabsize;
    s->tab[hash_code].suffix = c;
    s->tab[hash_code].hash_prefix = hash_prefix;

    s->tabsize++;

    if (s->tabsize >= (1 << s->bits) + (s->mode == FF_LZW_GIF))
        s->bits++;
}

/**
 * Clear LZW code table
 * @param s LZW state
 */
static void clearTable(LZWEncodeState * s)
{
    int i, h;

    writeCode(s, s->clear_code);
    s->bits = 9;
    for (i = 0; i < LZW_HASH_SIZE; i++) {
        s->tab[i].hash_prefix = LZW_PREFIX_FREE;
    }
    for (i = 0; i < 256; i++) {
        h = hash(0, i);
        s->tab[h].code = i;
        s->tab[h].suffix = i;
        s->tab[h].hash_prefix = LZW_PREFIX_EMPTY;
    }
    s->tabsize = 258;
}

/**
 * Calculate number of bytes written
 * @param s LZW encode state
 * @return Number of bytes written
 */
static int writtenBytes(LZWEncodeState *s){
    int ret = put_bits_count(&s->pb) >> 3;
    ret -= s->output_bytes;
    s->output_bytes += ret;
    return ret;
}

/**
 * Initialize LZW encoder. Please set s->clear_code, s->end_code and s->maxbits before run.
 * @param s LZW state
 * @param outbuf Output buffer
 * @param outsize Size of output buffer
 * @param maxbits Maximum length of code
 */
void ff_lzw_encode_init(LZWEncodeState *s, uint8_t *outbuf, int outsize,
                        int maxbits, enum FF_LZW_MODES mode,
                        void (*lzw_put_bits)(PutBitContext *, int, unsigned))
{
    s->clear_code = 256;
    s->end_code = 257;
    s->maxbits = maxbits;
    init_put_bits(&s->pb, outbuf, outsize);
    s->bufsize = outsize;
    av_assert0(s->maxbits >= 9 && s->maxbits <= LZW_MAXBITS);
    s->maxcode = 1 << s->maxbits;
    s->output_bytes = 0;
    s->last_code = LZW_PREFIX_EMPTY;
    s->bits = 9;
    s->mode = mode;
    s->put_bits = lzw_put_bits;
}

/**
 * LZW main compress function
 * @param s LZW state
 * @param inbuf Input buffer
 * @param insize Size of input buffer
 * @return Number of bytes written or -1 on error
 */
int ff_lzw_encode(LZWEncodeState * s, const uint8_t * inbuf, int insize)
{
    int i;

    if(insize * 3 > (s->bufsize - s->output_bytes) * 2){
        return -1;
    }

    if (s->last_code == LZW_PREFIX_EMPTY)
        clearTable(s);

    for (i = 0; i < insize; i++) {
        uint8_t c = *inbuf++;
        int code = findCode(s, c, s->last_code);
        if (s->tab[code].hash_prefix == LZW_PREFIX_FREE) {
            writeCode(s, s->last_code);
            addCode(s, c, s->last_code, code);
            code= hash(0, c);
        }
        s->last_code = s->tab[code].code;
        if (s->tabsize >= s->maxcode - 1) {
            clearTable(s);
        }
    }

    return writtenBytes(s);
}

/**
 * Write end code and flush bitstream
 * @param s LZW state
 * @return Number of bytes written or -1 on error
 */
int ff_lzw_encode_flush(LZWEncodeState *s,
                        void (*lzw_flush_put_bits)(PutBitContext *))
{
    if (s->last_code != -1)
        writeCode(s, s->last_code);
    writeCode(s, s->end_code);
    if (s->mode == FF_LZW_GIF)
        s->put_bits(&s->pb, 1, 0);

    lzw_flush_put_bits(&s->pb);
    s->last_code = -1;

    return writtenBytes(s);
}


Generated by: GCOVR (Version 4.1)

Line	Branch	Exec	Source
1			/*
2			* LZW encoder
3			* Copyright (c) 2007 Bartlomiej Wolowiec
4			*
5			* This file is part of FFmpeg.
6			*
7			* FFmpeg is free software; you can redistribute it and/or
8			* modify it under the terms of the GNU Lesser General Public
9			* License as published by the Free Software Foundation; either
10			* version 2.1 of the License, or (at your option) any later version.
11			*
12			* FFmpeg is distributed in the hope that it will be useful,
13			* but WITHOUT ANY WARRANTY; without even the implied warranty of
14			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15			* Lesser General Public License for more details.
16			*
17			* You should have received a copy of the GNU Lesser General Public
18			* License along with FFmpeg; if not, write to the Free Software
19			* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20			*/
21
22			/**
23			* @file
24			* LZW encoder
25			* @author Bartlomiej Wolowiec
26			*/
27
28			#include "avcodec.h"
29			#include "lzw.h"
30			#include "mathops.h"
31			#include "put_bits.h"
32
33			#define LZW_MAXBITS 12
34			#define LZW_SIZTABLE (1<<LZW_MAXBITS)
35			#define LZW_HASH_SIZE 16411
36			#define LZW_HASH_SHIFT 6
37
38			#define LZW_PREFIX_EMPTY -1
39			#define LZW_PREFIX_FREE -2
40
41			/** One code in hash table */
42			typedef struct Code{
43			/// Hash code of prefix, LZW_PREFIX_EMPTY if empty prefix, or LZW_PREFIX_FREE if no code
44			int hash_prefix;
45			int code; ///< LZW code
46			uint8_t suffix; ///< Last character in code block
47			}Code;
48
49			/** LZW encode state */
50			typedef struct LZWEncodeState {
51			int clear_code; ///< Value of clear code
52			int end_code; ///< Value of end code
53			Code tab[LZW_HASH_SIZE]; ///< Hash table
54			int tabsize; ///< Number of values in hash table
55			int bits; ///< Actual bits code
56			int bufsize; ///< Size of output buffer
57			PutBitContext pb; ///< Put bit context for output
58			int maxbits; ///< Max bits code
59			int maxcode; ///< Max value of code
60			int output_bytes; ///< Number of written bytes
61			int last_code; ///< Value of last output code or LZW_PREFIX_EMPTY
62			enum FF_LZW_MODES mode; ///< TIFF or GIF
63			void (put_bits)(PutBitContext , int, unsigned); ///< GIF is LE while TIFF is BE
64			}LZWEncodeState;
65
66
67			const int ff_lzw_encode_state_size = sizeof(LZWEncodeState);
68
69			/**
70			* Hash function adding character
71			* @param head LZW code for prefix
72			* @param add Character to add
73			* @return New hash value
74			*/
75		5529886	static inline int hash(int head, const int add)
76			{
77		5529886	head ^= (add << LZW_HASH_SHIFT);
78	✗✓	5529886	if (head >= LZW_HASH_SIZE)
79			head -= LZW_HASH_SIZE;
80			av_assert2(head >= 0 && head < LZW_HASH_SIZE);
81		5529886	return head;
82			}
83
84			/**
85			* Hash function calculates next hash value
86			* @param head Actual hash code
87			* @param offset Offset calculated by hashOffset
88			* @return New hash value
89			*/
90		1409932	static inline int hashNext(int head, const int offset)
91			{
92		1409932	head -= offset;
93	✓✓	1409932	if(head < 0)
94		1118268	head += LZW_HASH_SIZE;
95		1409932	return head;
96			}
97
98			/**
99			* Hash function calculates hash offset
100			* @param head Actual hash code
101			* @return Hash offset
102			*/
103		3541685	static inline int hashOffset(const int head)
104			{
105	✓✓	3541685	return head ? LZW_HASH_SIZE - head : 1;
106			}
107
108			/**
109			* Write one code to stream
110			* @param s LZW state
111			* @param c code to write
112			*/
113		1630012	static inline void writeCode(LZWEncodeState * s, int c)
114			{
115			av_assert2(0 <= c && c < 1 << s->bits);
116		1630012	s->put_bits(&s->pb, s->bits, c);
117		1630012	}
118
119
120			/**
121			* Find LZW code for block
122			* @param s LZW state
123			* @param c Last character in block
124			* @param hash_prefix LZW code for prefix
125			* @return LZW code for block or -1 if not found in table
126			*/
127		3541685	static inline int findCode(LZWEncodeState * s, uint8_t c, int hash_prefix)
128			{
129		3541685	int h = hash(FFMAX(hash_prefix, 0), c);
130		3541685	int hash_offset = hashOffset(h);
131
132	✓✓	4951617	while (s->tab[h].hash_prefix != LZW_PREFIX_FREE) {
133	✓✓	3325144	if ((s->tab[h].suffix == c)
134	✓✓	1965850	&& (s->tab[h].hash_prefix == hash_prefix))
135		1915212	return h;
136		1409932	h = hashNext(h, hash_offset);
137			}
138
139		1626473	return h;
140			}
141
142			/**
143			* Add block to LZW code table
144			* @param s LZW state
145			* @param c Last character in block
146			* @param hash_prefix LZW code for prefix
147			* @param hash_code LZW code for bytes block
148			*/
149		1626473	static inline void addCode(LZWEncodeState * s, uint8_t c, int hash_prefix, int hash_code)
150			{
151		1626473	s->tab[hash_code].code = s->tabsize;
152		1626473	s->tab[hash_code].suffix = c;
153		1626473	s->tab[hash_code].hash_prefix = hash_prefix;
154
155		1626473	s->tabsize++;
156
157	✓✓	1626473	if (s->tabsize >= (1 << s->bits) + (s->mode == FF_LZW_GIF))
158		1324	s->bits++;
159		1626473	}
160
161			/**
162			* Clear LZW code table
163			* @param s LZW state
164			*/
165		1413	static void clearTable(LZWEncodeState * s)
166			{
167			int i, h;
168
169		1413	writeCode(s, s->clear_code);
170		1413	s->bits = 9;
171	✓✓	23190156	for (i = 0; i < LZW_HASH_SIZE; i++) {
172		23188743	s->tab[i].hash_prefix = LZW_PREFIX_FREE;
173			}
174	✓✓	363141	for (i = 0; i < 256; i++) {
175		361728	h = hash(0, i);
176		361728	s->tab[h].code = i;
177		361728	s->tab[h].suffix = i;
178		361728	s->tab[h].hash_prefix = LZW_PREFIX_EMPTY;
179			}
180		1413	s->tabsize = 258;
181		1413	}
182
183			/**
184			* Calculate number of bytes written
185			* @param s LZW encode state
186			* @return Number of bytes written
187			*/
188		35140	static int writtenBytes(LZWEncodeState *s){
189		35140	int ret = put_bits_count(&s->pb) >> 3;
190		35140	ret -= s->output_bytes;
191		35140	s->output_bytes += ret;
192		35140	return ret;
193			}
194
195			/**
196			* Initialize LZW encoder. Please set s->clear_code, s->end_code and s->maxbits before run.
197			* @param s LZW state
198			* @param outbuf Output buffer
199			* @param outsize Size of output buffer
200			* @param maxbits Maximum length of code
201			*/
202		1063	void ff_lzw_encode_init(LZWEncodeState s, uint8_t outbuf, int outsize,
203			int maxbits, enum FF_LZW_MODES mode,
204			void (lzw_put_bits)(PutBitContext , int, unsigned))
205			{
206		1063	s->clear_code = 256;
207		1063	s->end_code = 257;
208		1063	s->maxbits = maxbits;
209		1063	init_put_bits(&s->pb, outbuf, outsize);
210		1063	s->bufsize = outsize;
211	✓✗✗✓	1063	av_assert0(s->maxbits >= 9 && s->maxbits <= LZW_MAXBITS);
212		1063	s->maxcode = 1 << s->maxbits;
213		1063	s->output_bytes = 0;
214		1063	s->last_code = LZW_PREFIX_EMPTY;
215		1063	s->bits = 9;
216		1063	s->mode = mode;
217		1063	s->put_bits = lzw_put_bits;
218		1063	}
219
220			/**
221			* LZW main compress function
222			* @param s LZW state
223			* @param inbuf Input buffer
224			* @param insize Size of input buffer
225			* @return Number of bytes written or -1 on error
226			*/
227		34077	int ff_lzw_encode(LZWEncodeState * s, const uint8_t * inbuf, int insize)
228			{
229			int i;
230
231	✗✓	34077	if(insize * 3 > (s->bufsize - s->output_bytes) * 2){
232			return -1;
233			}
234
235	✓✓	34077	if (s->last_code == LZW_PREFIX_EMPTY)
236		1063	clearTable(s);
237
238	✓✓	3575762	for (i = 0; i < insize; i++) {
239		3541685	uint8_t c = *inbuf++;
240		3541685	int code = findCode(s, c, s->last_code);
241	✓✓	3541685	if (s->tab[code].hash_prefix == LZW_PREFIX_FREE) {
242		1626473	writeCode(s, s->last_code);
243		1626473	addCode(s, c, s->last_code, code);
244		1626473	code= hash(0, c);
245			}
246		3541685	s->last_code = s->tab[code].code;
247	✓✓	3541685	if (s->tabsize >= s->maxcode - 1) {
248		350	clearTable(s);
249			}
250			}
251
252		34077	return writtenBytes(s);
253			}
254
255			/**
256			* Write end code and flush bitstream
257			* @param s LZW state
258			* @return Number of bytes written or -1 on error
259			*/
260		1063	int ff_lzw_encode_flush(LZWEncodeState *s,
261			void (lzw_flush_put_bits)(PutBitContext ))
262			{
263	✓✗	1063	if (s->last_code != -1)
264		1063	writeCode(s, s->last_code);
265		1063	writeCode(s, s->end_code);
266	✓✗	1063	if (s->mode == FF_LZW_GIF)
267		1063	s->put_bits(&s->pb, 1, 0);
268
269		1063	lzw_flush_put_bits(&s->pb);
270		1063	s->last_code = -1;
271
272		1063	return writtenBytes(s);
273			}