static void
compress(
int init_bits,
FILE *outfile,
ifun_t* ReadValue
)
{
register long fcode;
register code_int i = 0;
register int c;
register code_int ent;
register code_int disp;
register code_int hsize_reg;
register int hshift;
/*
* Set up the globals: g_init_bits - initial number of bits
* g_outfile - pointer to output file
*/
g_init_bits = init_bits;
g_outfile = outfile;
/*
* Set up the necessary values
*/
offset = 0;
out_count = 0;
clear_flg = 0;
in_count = 1;
maxcode = MAXCODE(n_bits = g_init_bits);
ClearCode = (1 << (init_bits - 1));
EOFCode = ClearCode + 1;
free_ent = ClearCode + 2;
char_init();
ent = GIFNextPixel( ReadValue );
hshift = 0;
for ( fcode = (long) hsize; fcode < 65536L; fcode *= 2L )
hshift++;
hshift = 8 - hshift; /* set hash code range bound */
hsize_reg = hsize;
cl_hash( (count_int) hsize_reg); /* clear hash table */
output( (code_int)ClearCode );
while ( (c = GIFNextPixel( ReadValue )) != EOF ) {
in_count++;
fcode = (long) (((long) c << maxbits) + ent);
/* i = (((code_int)c << hshift) ~ ent); */ /* xor hashing */
i = (((code_int)c << hshift) ^ ent); /* xor hashing */
if ( HashTabOf (i) == fcode ) {
ent = CodeTabOf (i);
continue;
} else if ( (long)HashTabOf (i) < 0 ) /* empty slot */
goto nomatch;
disp = hsize_reg - i; /* secondary hash (after G. Knott) */
if ( i == 0 )
disp = 1;
probe:
if ( (i -= disp) < 0 )
i += hsize_reg;
if ( HashTabOf (i) == fcode ) {
ent = CodeTabOf (i);
continue;
}
if ( (long)HashTabOf (i) > 0 )
goto probe;
nomatch:
output ( (code_int) ent );
out_count++;
ent = c;
if ( free_ent < maxmaxcode ) {
CodeTabOf (i) = free_ent++; /* code -> hashtable */
HashTabOf (i) = fcode;
} else
cl_block();
}
/*
* Put out the final code.
*/
output( (code_int)ent );
out_count++;
output( (code_int) EOFCode );
return;
}
static void
compress(int init_bits, gdIOCtxPtr outfile, gdImagePtr im, GifCtx *ctx)
{
register long fcode;
register code_int i /* = 0 */;
register int c;
register code_int ent;
register code_int disp;
register code_int hsize_reg;
register int hshift;
/*
* Set up the globals: g_init_bits - initial number of bits
* g_outfile - pointer to output file
*/
ctx->g_init_bits = init_bits;
ctx->g_outfile = outfile;
/*
* Set up the necessary values
*/
ctx->offset = 0;
ctx->out_count = 0;
ctx->clear_flg = 0;
ctx->in_count = 1;
ctx->maxcode = MAXCODE(ctx->n_bits = ctx->g_init_bits);
ctx->ClearCode = (1 << (init_bits - 1));
ctx->EOFCode = ctx->ClearCode + 1;
ctx->free_ent = ctx->ClearCode + 2;
char_init(ctx);
ent = GIFNextPixel( im, ctx );
hshift = 0;
for ( fcode = (long) hsize; fcode < 65536L; fcode *= 2L )
++hshift;
hshift = 8 - hshift; /* set hash code range bound */
hsize_reg = hsize;
cl_hash( (count_int) hsize_reg, ctx ); /* clear hash table */
output( (code_int)ctx->ClearCode, ctx );
#ifdef SIGNED_COMPARE_SLOW
while ( (c = GIFNextPixel( im )) != (unsigned) EOF ) {
#else /*SIGNED_COMPARE_SLOW*/
while ( (c = GIFNextPixel( im, ctx )) != EOF ) { /* } */
#endif /*SIGNED_COMPARE_SLOW*/
++(ctx->in_count);
fcode = (long) (((long) c << maxbits) + ent);
i = (((code_int)c << hshift) ^ ent); /* xor hashing */
if ( HashTabOf (i) == fcode ) {
ent = CodeTabOf (i);
continue;
} else if ( (long)HashTabOf (i) < 0 ) /* empty slot */
goto nomatch;
disp = hsize_reg - i; /* secondary hash (after G. Knott) */
if ( i == 0 )
disp = 1;
probe:
if ( (i -= disp) < 0 )
i += hsize_reg;
if ( HashTabOf (i) == fcode ) {
ent = CodeTabOf (i);
continue;
}
if ( (long)HashTabOf (i) > 0 )
goto probe;
nomatch:
output ( (code_int) ent, ctx );
++(ctx->out_count);
ent = c;
#ifdef SIGNED_COMPARE_SLOW
if ( (unsigned) ctx->free_ent < (unsigned) maxmaxcode) {
#else /*SIGNED_COMPARE_SLOW*/
if ( ctx->free_ent < maxmaxcode ) { /* } */
#endif /*SIGNED_COMPARE_SLOW*/
CodeTabOf (i) = ctx->free_ent++; /* code -> hashtable */
HashTabOf (i) = fcode;
} else
cl_block(ctx);
}
/*
* Put out the final code.
*/
output( (code_int)ent, ctx );
++(ctx->out_count);
output( (code_int) ctx->EOFCode, ctx );
}
/*****************************************************************
* TAG( output )
*
* Output the given code.
* Inputs:
* code: A n_bits-bit integer. If == -1, then EOF. This assumes
* that n_bits =< (long)wordsize - 1.
* Outputs:
* Outputs code to the file.
* Assumptions:
* Chars are 8 bits long.
* Algorithm:
* Maintain a GIFBITS character long buffer (so that 8 codes will
* fit in it exactly). Use the VAX insv instruction to insert each
* code in turn. When the buffer fills up empty it and start over.
*/
static const unsigned long masks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000F,
0x001F, 0x003F, 0x007F, 0x00FF,
0x01FF, 0x03FF, 0x07FF, 0x0FFF,
0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF };
/* Arbitrary value to mark output is done. When we see EOFCode, then we don't
* expect to see any more data. If we do (e.g. corrupt image inputs), cur_bits
* might be negative, so flag it to return early.
*/
#define CUR_BITS_FINISHED -1000
static void
output(code_int code, GifCtx *ctx)
{
if (ctx->cur_bits == CUR_BITS_FINISHED) {
return;
}
ctx->cur_accum &= masks[ ctx->cur_bits ];
if( ctx->cur_bits > 0 )
ctx->cur_accum |= ((long)code << ctx->cur_bits);
else
ctx->cur_accum = code;
ctx->cur_bits += ctx->n_bits;
while( ctx->cur_bits >= 8 ) {
char_out( (unsigned int)(ctx->cur_accum & 0xff), ctx );
ctx->cur_accum >>= 8;
ctx->cur_bits -= 8;
}
/*
* If the next entry is going to be too big for the code size,
* then increase it, if possible.
*/
if ( ctx->free_ent > ctx->maxcode || ctx->clear_flg ) {
if( ctx->clear_flg ) {
ctx->maxcode = MAXCODE (ctx->n_bits = ctx->g_init_bits);
ctx->clear_flg = 0;
} else {
++(ctx->n_bits);
if ( ctx->n_bits == maxbits )
ctx->maxcode = maxmaxcode;
else
ctx->maxcode = MAXCODE(ctx->n_bits);
}
}
if( code == ctx->EOFCode ) {
/*
* At EOF, write the rest of the buffer.
*/
while( ctx->cur_bits > 0 ) {
char_out( (unsigned int)(ctx->cur_accum & 0xff), ctx);
ctx->cur_accum >>= 8;
ctx->cur_bits -= 8;
}
/* Flag that it's done to prevent re-entry. */
ctx->cur_bits = CUR_BITS_FINISHED;
flush_char(ctx);
}
}
/*
* Clear out the hash table
*/
static void
cl_block (GifCtx *ctx) /* table clear for block compress */
{
cl_hash ( (count_int) hsize, ctx );
ctx->free_ent = ctx->ClearCode + 2;
ctx->clear_flg = 1;
output( (code_int)ctx->ClearCode, ctx);
}
static void
cl_hash(register count_int chsize, GifCtx *ctx) /* reset code table */
{
register count_int *htab_p = ctx->htab+chsize;
register long i;
register long m1 = -1;
i = chsize - 16;
do { /* might use Sys V memset(3) here */
*(htab_p-16) = m1;
*(htab_p-15) = m1;
*(htab_p-14) = m1;
*(htab_p-13) = m1;
*(htab_p-12) = m1;
*(htab_p-11) = m1;
*(htab_p-10) = m1;
*(htab_p-9) = m1;
*(htab_p-8) = m1;
*(htab_p-7) = m1;
*(htab_p-6) = m1;
*(htab_p-5) = m1;
*(htab_p-4) = m1;
*(htab_p-3) = m1;
*(htab_p-2) = m1;
*(htab_p-1) = m1;
htab_p -= 16;
} while ((i -= 16) >= 0);
for ( i += 16; i > 0; --i )
*--htab_p = m1;
}
/******************************************************************************
*
* GIF Specific routines
*
******************************************************************************/
/*
* Set up the 'byte output' routine
*/
static void
char_init(GifCtx *ctx)
{
ctx->a_count = 0;
}
/*
* Add a character to the end of the current packet, and if it is 254
* characters, flush the packet to disk.
*/
static void
char_out(int c, GifCtx *ctx)
{
ctx->accum[ ctx->a_count++ ] = c;
if( ctx->a_count >= 254 )
flush_char(ctx);
}
