ENH: reorder code to remove forward declarations
This commit is contained in:
Ken Martin
parent
3a44f2a47e
commit
d4ae4849f7
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@ -67,9 +67,6 @@ static const char_type magic_header[] = { "\037\235" }; /* 1F 9D */
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#define FIRST 257 /* first free entry */
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#define CLEAR 256 /* table clear output code */
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static void cl_hash(struct cmcompress_stream* cdata, count_int hsize); /* reset code table */
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static int cl_block (struct cmcompress_stream* cdata); /* table clear for block compress */
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static int output(struct cmcompress_stream* cdata, code_int code);
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#ifdef DEBUG
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static void prratio( FILE *stream, long int num, long int den);
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#endif
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@ -92,230 +89,6 @@ int cmcompress_compress_initialize(struct cmcompress_stream* cdata)
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return 1;
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}
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/*
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* compress stdin to stdout
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*
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* Algorithm: use open addressing double hashing (no chaining) on the
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* prefix code / next character combination. We do a variant of Knuth's
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* algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
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* secondary probe. Here, the modular division first probe is gives way
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* to a faster exclusive-or manipulation. Also do block compression with
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* an adaptive reset, whereby the code table is cleared when the compression
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* ratio decreases, but after the table fills. The variable-length output
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* codes are re-sized at this point, and a special CLEAR code is generated
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* for the decompressor. Late addition: construct the table according to
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* file size for noticeable speed improvement on small files. Please direct
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* questions about this implementation to ames!jaw.
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*/
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int cmcompress_compress_start(struct cmcompress_stream* cdata)
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{
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#ifndef COMPATIBLE
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if (cdata->nomagic == 0)
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{
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char headLast = (char)(cdata->maxbits | cdata->block_compress);
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cdata->output_stream(cdata, (const char*)magic_header, 2);
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cdata->output_stream(cdata, &headLast, 1);
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if(ferror(stdout))
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{
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printf("Error...\n");
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}
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}
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#endif /* COMPATIBLE */
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cdata->offset = 0;
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cdata->bytes_out = 3; /* includes 3-byte header mojo */
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cdata->out_count = 0;
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cdata->clear_flg = 0;
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cdata->ratio = 0;
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cdata->in_count = 1;
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cdata->checkpoint = CHECK_GAP;
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cdata->maxcode = MAXCODE(cdata->n_bits = INIT_BITS);
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cdata->free_ent = ((cdata->block_compress) ? FIRST : 256 );
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cdata->first_pass = 1;
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cdata->hshift = 0;
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for ( cdata->fcode = (long) cdata->hsize; cdata->fcode < 65536L; cdata->fcode *= 2L )
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{
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cdata->hshift++;
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}
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cdata->hshift = 8 - cdata->hshift; /* set hash code range bound */
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cdata->hsize_reg = cdata->hsize;
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cl_hash(cdata, (count_int) cdata->hsize_reg); /* clear hash table */
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return 1;
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}
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int cmcompress_compress(struct cmcompress_stream* cdata, void* buff, size_t n)
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{
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register code_int i;
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register int c;
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register int disp;
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unsigned char* input_buffer = (unsigned char*)buff;
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size_t cc;
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/*printf("cmcompress_compress(%p, %p, %d)\n", cdata, buff, n);*/
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if ( cdata->first_pass )
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{
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cdata->ent = input_buffer[0];
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++ input_buffer;
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-- n;
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cdata->first_pass = 0;
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}
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for ( cc = 0; cc < n; ++ cc )
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{
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c = input_buffer[cc];
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cdata->in_count++;
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cdata->fcode = (long) (((long) c << cdata->maxbits) + cdata->ent);
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i = ((c << cdata->hshift) ^ cdata->ent); /* xor hashing */
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if ( htabof (i) == cdata->fcode )
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{
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cdata->ent = codetabof (i);
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continue;
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}
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else if ( (long)htabof (i) < 0 ) /* empty slot */
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{
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goto nomatch;
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}
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disp = cdata->hsize_reg - i; /* secondary hash (after G. Knott) */
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if ( i == 0 )
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{
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disp = 1;
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}
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probe:
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if ( (i -= disp) < 0 )
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{
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i += cdata->hsize_reg;
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}
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if ( htabof (i) == cdata->fcode )
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{
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cdata->ent = codetabof (i);
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continue;
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}
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if ( (long)htabof (i) > 0 )
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{
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goto probe;
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}
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nomatch:
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if ( !output(cdata, (code_int) cdata->ent ) )
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{
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return 0;
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}
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cdata->out_count++;
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cdata->ent = c;
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if (
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#ifdef SIGNED_COMPARE_SLOW
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(unsigned) cdata->free_ent < (unsigned) cdata->maxmaxcode
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#else
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cdata->free_ent < cdata->maxmaxcode
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#endif
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)
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{
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codetabof (i) = (unsigned short)(cdata->free_ent++); /* code -> hashtable */
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htabof (i) = cdata->fcode;
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}
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else if ( (count_int)cdata->in_count >= cdata->checkpoint && cdata->block_compress )
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{
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if ( !cl_block (cdata) )
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{
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return 0;
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}
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}
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}
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return 1;
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}
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int cmcompress_compress_finalize(struct cmcompress_stream* cdata)
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{
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/*
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* Put out the final code.
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*/
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if ( !output(cdata, (code_int)cdata->ent ) )
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{
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return 0;
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}
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cdata->out_count++;
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if ( !output(cdata, (code_int)-1 ) )
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{
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return 0;
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}
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if(cdata->bytes_out > cdata->in_count) /* exit(2) if no savings */
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{
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return 0;
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}
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return 1;
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}
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static int cl_block (struct cmcompress_stream* cdata) /* table clear for block compress */
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{
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register long int rat;
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cdata->checkpoint = cdata->in_count + CHECK_GAP;
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#ifdef DEBUG
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if ( cdata->debug )
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{
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fprintf ( stderr, "count: %ld, ratio: ", cdata->in_count );
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prratio ( stderr, cdata->in_count, cdata->bytes_out );
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fprintf ( stderr, "\n");
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}
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#endif /* DEBUG */
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if(cdata->in_count > 0x007fffff)
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{ /* shift will overflow */
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rat = cdata->bytes_out >> 8;
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if(rat == 0)
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{ /* Don't divide by zero */
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rat = 0x7fffffff;
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}
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else
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{
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rat = cdata->in_count / rat;
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}
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}
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else
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{
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rat = (cdata->in_count << 8) / cdata->bytes_out; /* 8 fractional bits */
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}
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if ( rat > cdata->ratio )
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{
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cdata->ratio = rat;
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}
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else
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{
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cdata->ratio = 0;
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#ifdef DEBUG
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if(cdata->verbose)
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{
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dump_tab(); /* dump string table */
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}
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#endif
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cl_hash (cdata, (count_int) cdata->hsize );
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cdata->free_ent = FIRST;
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cdata->clear_flg = 1;
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if ( !output (cdata, (code_int) CLEAR ) )
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{
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return 0;
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}
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#ifdef DEBUG
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if(cdata->debug)
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{
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fprintf ( stderr, "clear\n" );
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}
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#endif /* DEBUG */
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}
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return 1;
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}
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static void cl_hash(struct cmcompress_stream* cdata, count_int hsize) /* reset code table */
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{
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register count_int *htab_p = cdata->htab+hsize;
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@ -350,28 +123,6 @@ static void cl_hash(struct cmcompress_stream* cdata, count_int hsize) /* rese
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}
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}
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#if defined(DEBUG)
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static void prratio(FILE *stream, long int num, long int den)
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{
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register int q; /* Doesn't need to be long */
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if(num > 214748L)
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{ /* 2147483647/10000 */
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q = num / (den / 10000L);
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}
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else
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{
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q = 10000L * num / den; /* Long calculations, though */
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}
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if (q < 0)
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{
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putc('-', stream);
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q = -q;
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}
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fprintf(stream, "%d.%02d%%", q / 100, q % 100);
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}
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#endif
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/*-
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* Output the given code.
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* Inputs:
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@ -549,3 +300,252 @@ static int output(struct cmcompress_stream* cdata, code_int code)
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}
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return 1;
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}
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/*
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* compress stdin to stdout
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*
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* Algorithm: use open addressing double hashing (no chaining) on the
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* prefix code / next character combination. We do a variant of Knuth's
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* algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
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* secondary probe. Here, the modular division first probe is gives way
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* to a faster exclusive-or manipulation. Also do block compression with
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* an adaptive reset, whereby the code table is cleared when the compression
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* ratio decreases, but after the table fills. The variable-length output
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* codes are re-sized at this point, and a special CLEAR code is generated
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* for the decompressor. Late addition: construct the table according to
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* file size for noticeable speed improvement on small files. Please direct
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* questions about this implementation to ames!jaw.
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*/
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int cmcompress_compress_start(struct cmcompress_stream* cdata)
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{
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#ifndef COMPATIBLE
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if (cdata->nomagic == 0)
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{
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char headLast = (char)(cdata->maxbits | cdata->block_compress);
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cdata->output_stream(cdata, (const char*)magic_header, 2);
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cdata->output_stream(cdata, &headLast, 1);
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if(ferror(stdout))
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{
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printf("Error...\n");
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}
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}
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#endif /* COMPATIBLE */
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cdata->offset = 0;
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cdata->bytes_out = 3; /* includes 3-byte header mojo */
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cdata->out_count = 0;
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cdata->clear_flg = 0;
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cdata->ratio = 0;
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cdata->in_count = 1;
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cdata->checkpoint = CHECK_GAP;
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cdata->maxcode = MAXCODE(cdata->n_bits = INIT_BITS);
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cdata->free_ent = ((cdata->block_compress) ? FIRST : 256 );
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cdata->first_pass = 1;
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cdata->hshift = 0;
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for ( cdata->fcode = (long) cdata->hsize; cdata->fcode < 65536L; cdata->fcode *= 2L )
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{
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cdata->hshift++;
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}
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cdata->hshift = 8 - cdata->hshift; /* set hash code range bound */
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cdata->hsize_reg = cdata->hsize;
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cl_hash(cdata, (count_int) cdata->hsize_reg); /* clear hash table */
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return 1;
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}
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static int cl_block (struct cmcompress_stream* cdata) /* table clear for block compress */
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{
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register long int rat;
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cdata->checkpoint = cdata->in_count + CHECK_GAP;
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#ifdef DEBUG
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if ( cdata->debug )
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{
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fprintf ( stderr, "count: %ld, ratio: ", cdata->in_count );
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prratio ( stderr, cdata->in_count, cdata->bytes_out );
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fprintf ( stderr, "\n");
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}
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#endif /* DEBUG */
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if(cdata->in_count > 0x007fffff)
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{ /* shift will overflow */
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rat = cdata->bytes_out >> 8;
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if(rat == 0)
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{ /* Don't divide by zero */
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rat = 0x7fffffff;
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}
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else
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{
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rat = cdata->in_count / rat;
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}
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}
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else
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{
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rat = (cdata->in_count << 8) / cdata->bytes_out; /* 8 fractional bits */
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}
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if ( rat > cdata->ratio )
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{
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cdata->ratio = rat;
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}
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else
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{
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cdata->ratio = 0;
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#ifdef DEBUG
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if(cdata->verbose)
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{
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dump_tab(); /* dump string table */
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}
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#endif
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cl_hash (cdata, (count_int) cdata->hsize );
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cdata->free_ent = FIRST;
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cdata->clear_flg = 1;
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if ( !output (cdata, (code_int) CLEAR ) )
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{
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return 0;
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}
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#ifdef DEBUG
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if(cdata->debug)
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{
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fprintf ( stderr, "clear\n" );
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}
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#endif /* DEBUG */
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}
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return 1;
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}
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int cmcompress_compress(struct cmcompress_stream* cdata, void* buff, size_t n)
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{
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register code_int i;
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register int c;
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register int disp;
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unsigned char* input_buffer = (unsigned char*)buff;
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size_t cc;
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/*printf("cmcompress_compress(%p, %p, %d)\n", cdata, buff, n);*/
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if ( cdata->first_pass )
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{
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cdata->ent = input_buffer[0];
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++ input_buffer;
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-- n;
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cdata->first_pass = 0;
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}
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for ( cc = 0; cc < n; ++ cc )
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{
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c = input_buffer[cc];
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cdata->in_count++;
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cdata->fcode = (long) (((long) c << cdata->maxbits) + cdata->ent);
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i = ((c << cdata->hshift) ^ cdata->ent); /* xor hashing */
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if ( htabof (i) == cdata->fcode )
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{
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cdata->ent = codetabof (i);
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continue;
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}
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else if ( (long)htabof (i) < 0 ) /* empty slot */
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{
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goto nomatch;
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}
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disp = cdata->hsize_reg - i; /* secondary hash (after G. Knott) */
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if ( i == 0 )
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{
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disp = 1;
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}
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probe:
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if ( (i -= disp) < 0 )
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{
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i += cdata->hsize_reg;
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}
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if ( htabof (i) == cdata->fcode )
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{
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cdata->ent = codetabof (i);
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continue;
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}
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if ( (long)htabof (i) > 0 )
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{
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goto probe;
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}
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nomatch:
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if ( !output(cdata, (code_int) cdata->ent ) )
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{
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return 0;
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}
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cdata->out_count++;
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cdata->ent = c;
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if (
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#ifdef SIGNED_COMPARE_SLOW
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(unsigned) cdata->free_ent < (unsigned) cdata->maxmaxcode
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#else
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cdata->free_ent < cdata->maxmaxcode
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#endif
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)
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{
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codetabof (i) = (unsigned short)(cdata->free_ent++); /* code -> hashtable */
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htabof (i) = cdata->fcode;
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}
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else if ( (count_int)cdata->in_count >= cdata->checkpoint && cdata->block_compress )
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{
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if ( !cl_block (cdata) )
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{
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return 0;
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}
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}
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}
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return 1;
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}
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int cmcompress_compress_finalize(struct cmcompress_stream* cdata)
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{
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/*
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* Put out the final code.
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*/
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if ( !output(cdata, (code_int)cdata->ent ) )
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{
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return 0;
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}
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cdata->out_count++;
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if ( !output(cdata, (code_int)-1 ) )
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{
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return 0;
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}
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if(cdata->bytes_out > cdata->in_count) /* exit(2) if no savings */
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{
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return 0;
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}
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return 1;
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}
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#if defined(DEBUG)
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static void prratio(FILE *stream, long int num, long int den)
|
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{
|
||||
register int q; /* Doesn't need to be long */
|
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|
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if(num > 214748L)
|
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{ /* 2147483647/10000 */
|
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q = num / (den / 10000L);
|
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}
|
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else
|
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{
|
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q = 10000L * num / den; /* Long calculations, though */
|
||||
}
|
||||
if (q < 0)
|
||||
{
|
||||
putc('-', stream);
|
||||
q = -q;
|
||||
}
|
||||
fprintf(stream, "%d.%02d%%", q / 100, q % 100);
|
||||
}
|
||||
#endif
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue