Ejemplo n.º 1
0
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);
}
Ejemplo n.º 2
0
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;
}
Ejemplo n.º 3
0
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);
}