/*-
* compress write
*
* Algorithm: use open addressing double hashing (no chaining) on the
* prefix code / next character combination. We do a variant of Knuth's
* algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
* secondary probe. Here, the modular division first probe is gives way
* to a faster exclusive-or manipulation. Also do block compression with
* an adaptive reset, whereby the code table is cleared when the compression
* ratio decreases, but after the table fills. The variable-length output
* codes are re-sized at this point, and a special CLEAR code is generated
* for the decompressor. Late addition: construct the table according to
* file size for noticeable speed improvement on small files. Please direct
* questions about this implementation to ames!jaw.
*/
static int
zwrite(void *cookie, const char *wbp, int num)
{
code_int i;
int c, disp;
struct s_zstate *zs;
const u_char *bp;
u_char tmp;
int count;
if (num == 0)
return (0);
zs = cookie;
count = num;
bp = wbp;
if (state == S_MIDDLE)
goto middle;
state = S_MIDDLE;
maxmaxcode = 1L << maxbits;
if (fwrite(magic_header,
sizeof(char), sizeof(magic_header), fp) != sizeof(magic_header))
return (-1);
tmp = (u_char)((maxbits) | block_compress);
if (fwrite(&tmp, sizeof(char), sizeof(tmp), fp) != sizeof(tmp))
return (-1);
offset = 0;
bytes_out = 3; /* Includes 3-byte header mojo. */
out_count = 0;
clear_flg = 0;
ratio = 0;
in_count = 1;
checkpoint = CHECK_GAP;
maxcode = MAXCODE(n_bits = INIT_BITS);
free_ent = ((block_compress) ? FIRST : 256);
ent = *bp++;
--count;
hshift = 0;
for (fcode = (long)hsize; fcode < 65536L; fcode *= 2L)
hshift++;
hshift = 8 - hshift; /* Set hash code range bound. */
hsize_reg = hsize;
cl_hash(zs, (count_int)hsize_reg); /* Clear hash table. */
middle: for (i = 0; count--;) {
c = *bp++;
in_count++;
fcode = (long)(((long)c << maxbits) + ent);
i = ((c << hshift) ^ ent); /* Xor hashing. */
if (htabof(i) == fcode) {
ent = codetabof(i);
continue;
} else if ((long)htabof(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 (htabof(i) == fcode) {
ent = codetabof(i);
continue;
}
if ((long)htabof(i) >= 0)
goto probe;
nomatch: if (output(zs, (code_int) ent) == -1)
return (-1);
out_count++;
ent = c;
if (free_ent < maxmaxcode) {
codetabof(i) = free_ent++; /* code -> hashtable */
htabof(i) = fcode;
} else if ((count_int)in_count >=
checkpoint && block_compress) {
if (cl_block(zs) == -1)
return (-1);
}
}
return (num);
}
void compress(void)
{
register long fcode;
register code_int i = 0;
register int c;
register code_int ent;
register int disp;
register code_int hsize_reg;
register int hshift;
offset = 0;
bytes_out = 3;
out_count = 0;
clear_flg = 0;
ratio = 0;
in_count = 1;
checkpoint = 10000;
maxcode = ((1 << (n_bits = 9)) - 1);
free_ent = ((block_compress) ? (257) : (256));
ent = getbyte();
hshift = 0;
for (fcode = (long) hsize; fcode < 65536L; fcode *= 2L) {
hshift++;
}
hshift = 8 - hshift;
hsize_reg = hsize;
cl_hash((count_int) hsize_reg);
while (InCnt > 0) {
int apsim_bound111 = 0;
c = getbyte();
in_count++;
fcode = (long) (((long) c << maxbits) + ent);
i = ((c << hshift) ^ ent);
if (htab[i] == fcode) {
ent = codetab[i];
continue;
} else if ((long) htab[i] < 0) {
goto nomatch;
}
disp = hsize_reg - i;
if (i == 0) {
disp = 1;
}
probe:
if ((i -= disp) < 0) {
i += hsize_reg;
}
if (htab[i] == fcode) {
ent = codetab[i];
continue;
}
if ((long) htab[i] > 0 && (++apsim_bound111 < in_count))
goto probe;
nomatch:
out_count++;
ent = c;
if (free_ent < maxmaxcode) {
codetab[i] = free_ent++;
htab[i] = fcode;
} else if (((count_int) in_count >= checkpoint) && (block_compress)) {
cl_block();
}
}
if (bytes_out > in_count) {
exit_stat = 2;
}
return;
}
void
compress(void)
{
register long fcode;
register code_int i = 0;
register int c;
register code_int ent;
register int disp;
register code_int hsize_reg;
register int hshift;
offset = 0;
bytes_out = 3; /* includes 3-byte header mojo */
out_count = 0;
clear_flg = 0;
ratio = 0;
in_count = 1;
checkpoint = CHECK_GAP;
maxcode = MAXCODE(n_bits = INIT_BITS);
free_ent = ((block_compress) ? (FIRST) : (256));
ent = getbyte();
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 */
while (InCnt > 0) { /* apsim_loop 11 0 */
int apsim_bound111 = 0;
c = getbyte(); /* decrements InCnt */
in_count++;
fcode = (long) (((long) c << maxbits) + ent);
i = ((c << hshift) ^ ent); /* xor hashing */
if (htabof(i) == fcode) {
ent = codetabof(i);
continue;
} else if ((long) htabof(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) { /* apsim_loop 111 11 */
i += hsize_reg;
}
if (htabof(i) == fcode) {
ent = codetabof(i);
continue;
}
if ((long) htabof(i) > 0 && (++apsim_bound111 < in_count))
goto probe;
nomatch:
out_count++;
ent = c;
if (free_ent < maxmaxcode) {
codetabof(i) = free_ent++; /* apsim_unknown codetab */
htabof(i) = fcode; /* apsim_unknown htab */
} else if (((count_int) in_count >= checkpoint) && (block_compress)) {
cl_block();
}
}
if (bytes_out > in_count) { /* exit(2) if no savings */
exit_stat = 2;
}
return;
}
int main() {
register long fcode;
register code_int i = 0;
register int c;
register code_int ent;
#ifdef XENIX_16
register code_int disp;
#else /* Normal machine */
register int disp;
#endif
register code_int hsize_reg;
register int hshift;
#ifndef COMPATIBLE
if (nomagic == 0) {
/* putchar(magic_header[0]); putchar(magic_header[1]);
putchar((char)(maxbits | block_compress)); */
}
#endif /* COMPATIBLE */
offset = 0;
bytes_out = 3; /* includes 3-byte header mojo */
out_count = 0;
clear_flg = 0;
ratio = 0;
in_count = 1;
printf("main: bytes_out %d... hsize %d\n", (int)bytes_out, (int)hsize);
checkpoint = CHECK_GAP;
maxcode = MAXCODE(n_bits = INIT_BITS);
free_ent = ((block_compress) ? FIRST : 256 );
ent = '\0'; /* getchar (); */
hshift = 0;
for ( fcode = (long) hsize; fcode < 65536L; fcode *= 2L )
hshift++;
hshift = 8 - hshift; /* set hash code range bound */
printf("main: hshift %d...\n", hshift);
hsize_reg = hsize;
cl_hash( (count_int) hsize_reg); /* clear hash table */
/*#ifdef SIGNED_COMPARE_SLOW
while ( (c = getchar()) != (unsigned) EOF ) {
#else
while ( (c = getchar()) != EOF ) {
#endif*/
printf("main: bytes_out %d...\n", (int)bytes_out);
printf("main: hsize_reg %d...\n", (int)hsize_reg);
printf("main: before compress %d...\n", (int)in_count);
while (in_count < BYTES_TO_COMPRESS) {
c = in_count % 255;
printf("main: compressing %d...\n", (int)in_count);
in_count++;
fcode = (long) (((long) c << maxbits) + ent);
i = (((long)c << hshift) ^ ent); /* xor hashing */
if ( htabof (i) == fcode ) {
ent = codetabof (i);
continue;
} else if ( (long)htabof (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 ( htabof (i) == fcode ) {
ent = codetabof (i);
continue;
}
if ( (long)htabof (i) > 0 )
goto probe;
nomatch:
output ( (code_int) ent );
out_count++;
ent = c;
#ifdef SIGNED_COMPARE_SLOW
if ( (unsigned) free_ent < (unsigned) maxmaxcode) {
#else
if ( free_ent < maxmaxcode ) {
#endif
codetabof (i) = free_ent++; /* code -> hashtable */
htabof (i) = fcode;
}
else if ( (count_int)in_count >= checkpoint && block_compress )
cl_block ();
}
/*
* Put out the final code.
*/
printf("main: output...\n");
output( (code_int)ent );
out_count++;
output( (code_int)-1 );
if(bytes_out > in_count) /* exit(2) if no savings */
exit_stat = 2;
printf("main: end...\n");
report (0xdeaddead);
return 0;
}
/*****************************************************************
* 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 BITS 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 char buf[BITS];
#ifndef vax
char_type lmask[9] = {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00};
char_type rmask[9] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
#endif /* vax */
void output( code )
code_int code;
{
/*
* On the VAX, it is important to have the register declarations
* in exactly the order given, or the asm will break.
*/
register int r_off = offset, bits= n_bits;
register char * bp = buf;
if ( code >= 0 ) {
#ifdef vax
/* VAX DEPENDENT!! Implementation on other machines is below.
*
* Translation: Insert BITS bits from the argument starting at
* offset bits from the beginning of buf.
*/
0; /* Work around for pcc -O bug with asm and if stmt */
asm( "insv 4(ap),r11,r10,(r9)" );
#else /* not a vax */
/*
* byte/bit numbering on the VAX is simulated by the following code
*/
/*
* Get to the first byte.
*/
bp += (r_off >> 3);
r_off &= 7;
/*
* Since code is always >= 8 bits, only need to mask the first
* hunk on the left.
*/
*bp = (*bp & rmask[r_off]) | ((code << r_off) & lmask[r_off]);
bp++;
bits -= (8 - r_off);
code >>= 8 - r_off;
/* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */
if ( bits >= 8 ) {
*bp++ = code;
code >>= 8;
bits -= 8;
}
/* Last bits. */
if(bits)
*bp = code;
#endif /* vax */
offset += n_bits;
if ( offset == (n_bits << 3) ) {
bp = buf;
bits = n_bits;
bytes_out += bits;
/* do
putchar(*bp++); */
while(--bits);
offset = 0;
}
/*
* If the next entry is going to be too big for the code size,
* then increase it, if possible.
*/
if ( free_ent > maxcode || (clear_flg > 0))
{
/*
* Write the whole buffer, because the input side won't
* discover the size increase until after it has read it.
*/
if ( offset > 0 ) {
/* if( fwrite( buf, 1, n_bits, stdout ) != n_bits)
writeerr(); */
bytes_out += n_bits;
}
offset = 0;
if ( clear_flg ) {
maxcode = MAXCODE (n_bits = INIT_BITS);
clear_flg = 0;
}
else {
n_bits++;
if ( n_bits == maxbits )
maxcode = maxmaxcode;
else
maxcode = MAXCODE(n_bits);
}
}
} else {
static void compress(int init_bits, FILE *outfile, byte *data, int len, struct GifStore *aGifStore)
{ register long fcode;
register int i = 0;
register int c;
register int ent;
register int disp;
register int hsize_reg;
register int hshift;
unsigned short codetab [HSIZE];
count_int htab [HSIZE];
/*
* Set up the globals: g_init_bits - initial number of bits
* g_outfile - pointer to output file
*/
aGifStore->g_init_bits = init_bits;
aGifStore->g_outfile = outfile;
/* initialize 'compress' globals */
memset((char *) htab, 0, sizeof(htab));
memset((char *) codetab, 0, sizeof(codetab));
aGifStore->free_ent = 0;
aGifStore->clear_flg = 0;
aGifStore->cur_accum = 0;
aGifStore->cur_bits = 0;
/*
* Set up the necessary values
*/
aGifStore->clear_flg = 0;
aGifStore->maxcode = MAXCODE(aGifStore->n_bits = aGifStore->g_init_bits);
aGifStore->ClearCode = 1 << (init_bits - 1);
aGifStore->EOFCode = aGifStore->ClearCode + 1;
aGifStore->free_ent = aGifStore->ClearCode + 2;
aGifStore->a_count = 0;
ent = aGifStore->pc2nc[*data++]; len--;
hshift = 0;
for ( fcode = (long)HSIZE; fcode < 65536L; fcode *= 2L )
hshift++;
hshift = 8 - hshift; /* set hash code range bound */
hsize_reg = HSIZE;
cl_hash2( (count_int) hsize_reg, htab); /* clear hash table */
output(aGifStore->ClearCode, aGifStore);
while (len)
{ c = aGifStore->pc2nc[*data++];
len--;
fcode = (long) ( ( (long) c << XV_BITS) + ent);
i = (((int) c << hshift) ^ ent); /* xor hashing */
if ( htab[i] == fcode )
{ ent = codetab[i];
continue;
}
else if ( (long)htab[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 ( htab[i] == fcode )
{ ent = codetab[i];
continue;
}
if ( (long)htab[i] >= 0 )
goto probe;
nomatch:
output(ent, aGifStore);
ent = c;
if ( aGifStore->free_ent < (1<<XV_BITS) )
{ codetab[i] = (unsigned short)(aGifStore->free_ent++); /* code -> hashtable */
htab[i] = fcode;
}
else
cl_block(htab, aGifStore);
}
/* Put out the final code */
output(ent, aGifStore);
output(aGifStore->EOFCode, aGifStore);
}
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, FILE *outfile, byte *data, int len)
{
register long fcode;
register int i = 0;
register int c;
register int ent;
register int disp;
register 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;
/* initialize 'compress' globals */
maxbits = XV_BITS;
maxmaxcode = 1<<XV_BITS;
memset(htab, 0, sizeof(htab));
memset(codetab, 0, sizeof(codetab));
hsize = HSIZE;
free_ent = 0;
clear_flg = 0;
in_count = 1;
out_count = 0;
cur_accum = 0;
cur_bits = 0;
/* Set up the necessary values */
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 = pc2nc[*data++];
len--;
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(ClearCode);
while (len) {
c = pc2nc[*data++];
len--;
in_count++;
fcode = (long)(((long) c << maxbits) + ent);
i = (((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(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(ent);
out_count++;
output(EOFCode);
}
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);
}
compress() {
register long fcode;
register code_int i = 0;
register int c;
register code_int ent;
#ifdef XENIX_16
register code_int disp;
#else /* Normal machine */
register int disp;
#endif
register code_int hsize_reg;
register int hshift;
#ifndef COMPATIBLE
if (nomagic == 0) {
putbyte(magic_header[0]); putbyte(magic_header[1]);
putbyte((char)(maxbits | block_compress));
}
#endif /* COMPATIBLE */
offset = 0;
bytes_out = 3; /* includes 3-byte header mojo */
out_count = 0;
clear_flg = 0;
ratio = 0;
in_count = 1;
checkpoint = CHECK_GAP;
maxcode = MAXCODE(n_bits = INIT_BITS);
free_ent = ((block_compress) ? FIRST : 256 );
ent = getbyte ();
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 */
#ifdef SIGNED_COMPARE_SLOW
while ( (c = getbyte()) != (unsigned) EOF ) {
#else
while ( (c = getbyte()) != EOF ) {
#endif
in_count++;
fcode = (long) (((long) c << maxbits) + ent);
i = ((c << hshift) ^ ent); /* xor hashing */
if ( htabof (i) == fcode ) {
ent = codetabof (i);
continue;
} else if ( (long)htabof (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 ( htabof (i) == fcode ) {
ent = codetabof (i);
continue;
}
if ( (long)htabof (i) > 0 )
goto probe;
nomatch:
output ( (code_int) ent );
out_count++;
ent = c;
#ifdef SIGNED_COMPARE_SLOW
if ( (unsigned) free_ent < (unsigned) maxmaxcode) {
#else
if ( free_ent < maxmaxcode ) {
#endif
codetabof (i) = free_ent++; /* code -> hashtable */
htabof (i) = fcode;
}
else if ( (count_int)in_count >= checkpoint && block_compress )
cl_block ();
}
/*
* Put out the final code.
*/
output( (code_int)ent );
out_count++;
output( (code_int)-1 );
/*
* Print out stats on stderr
*/
if(zcat_flg == 0 && !quiet) {
#ifdef DEBUG
fprintf( stderr,
"%ld chars in, %ld codes (%ld bytes) out, compression factor: ",
in_count, out_count, bytes_out );
prratio( stderr, in_count, bytes_out );
fprintf( stderr, "\n");
fprintf( stderr, "\tCompression as in compact: " );
prratio( stderr, in_count-bytes_out, in_count );
fprintf( stderr, "\n");
fprintf( stderr, "\tLargest code (of last block) was %d (%d bits)\n",
free_ent - 1, n_bits );
#else /* !DEBUG */
fprintf( stderr, "Compression: " );
prratio( stderr, in_count-bytes_out, in_count );
#endif /* DEBUG */
}
if(bytes_out > in_count) /* exit(2) if no savings */
exit_stat = 2;
return;
}
/*****************************************************************
* 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 BITS 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 char buf[BITS];
char_type lmask[9] = {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00};
char_type rmask[9] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
output( code )
code_int code;
{
#ifdef DEBUG
static int col = 0;
#endif /* DEBUG */
/*
* On the VAX, it is important to have the register declarations
* in exactly the order given, or the asm will break.
*/
register int r_off = offset, bits= n_bits;
register char * bp = buf;
#ifdef DEBUG
if ( verbose )
fprintf( stderr, "%5d%c", code,
(col+=6) >= 74 ? (col = 0, '\n') : ' ' );
#endif /* DEBUG */
if ( code >= 0 ) {
/*
* byte/bit numbering on the VAX is simulated by the following code
*/
/*
* Get to the first byte.
*/
bp += (r_off >> 3);
r_off &= 7;
/*
* Since code is always >= 8 bits, only need to mask the first
* hunk on the left.
*/
*bp = (*bp & rmask[r_off]) | (code << r_off) & lmask[r_off];
bp++;
bits -= (8 - r_off);
code >>= 8 - r_off;
/* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */
if ( bits >= 8 ) {
*bp++ = code;
code >>= 8;
bits -= 8;
}
/* Last bits. */
if(bits)
*bp = code;
offset += n_bits;
if ( offset == (n_bits << 3) ) {
bp = buf;
bits = n_bits;
bytes_out += bits;
do
putbyte(*bp++);
while(--bits);
offset = 0;
}
/*
* If the next entry is going to be too big for the code size,
* then increase it, if possible.
*/
if ( free_ent > maxcode || (clear_flg > 0))
{
/*
* Write the whole buffer, because the input side won't
* discover the size increase until after it has read it.
*/
if ( offset > 0 ) {
writebytes( buf, n_bits );
bytes_out += n_bits;
}
offset = 0;
if ( clear_flg ) {
maxcode = MAXCODE (n_bits = INIT_BITS);
clear_flg = 0;
}
else {
n_bits++;
if ( n_bits == maxbits )
maxcode = maxmaxcode;
else
maxcode = MAXCODE(n_bits);
}
#ifdef DEBUG
if ( debug ) {
fprintf( stderr, "\nChange to %d bits\n", n_bits );
col = 0;
}
#endif /* DEBUG */
}
} else {
/*
* At EOF, write the rest of the buffer.
*/
if ( offset > 0 )