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#ifndef lint |
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static const char RCSid[] = "$Id: color.c,v 2.25 2023/06/30 15:00:32 greg Exp $"; |
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#endif |
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/* |
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* color.c - routines for color calculations. |
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* |
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* Externals declared in color.h |
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*/ |
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|
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#include "copyright.h" |
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|
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <math.h> |
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#include "color.h" |
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|
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#ifdef getc_unlocked /* avoid horrendous overhead of flockfile */ |
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#undef getc |
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#undef putc |
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#undef ferror |
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#define getc getc_unlocked |
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#define putc putc_unlocked |
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#define ferror ferror_unlocked |
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#endif |
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|
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#define MINELEN 8 /* minimum scanline length for encoding */ |
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#define MAXELEN 0x7fff /* maximum scanline length for encoding */ |
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#define MINRUN 4 /* minimum run length */ |
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|
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|
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void * |
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tempbuffer( /* get a temporary buffer */ |
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unsigned int len |
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) |
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{ |
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static void *tempbuf = NULL; |
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static unsigned int tempbuflen = 0; |
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|
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if (!len) { /* call to free */ |
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if (tempbuflen) { |
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free(tempbuf); |
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tempbuf = NULL; |
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tempbuflen = 0; |
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} |
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return(NULL); |
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} |
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if (len <= tempbuflen) /* big enough already? */ |
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return(tempbuf); |
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/* else free & reallocate */ |
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if (tempbuflen) |
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free(tempbuf); |
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tempbuf = malloc(len); |
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tempbuflen = len*(tempbuf != NULL); |
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return(tempbuf); |
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} |
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|
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|
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int |
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fwritecolrs( /* write out a colr scanline */ |
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COLR *scanline, |
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int len, |
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FILE *fp |
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) |
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{ |
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int i, j, beg, cnt = 1; |
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int c2; |
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|
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if ((len < MINELEN) | (len > MAXELEN)) /* OOBs, write out flat */ |
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return(fwrite((char *)scanline,sizeof(COLR),len,fp) - len); |
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/* put magic header */ |
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putc(2, fp); |
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putc(2, fp); |
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putc(len>>8, fp); |
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putc(len&0xff, fp); |
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/* put components seperately */ |
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for (i = 0; i < 4; i++) { |
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for (j = 0; j < len; j += cnt) { /* find next run */ |
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for (beg = j; beg < len; beg += cnt) { |
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for (cnt = 1; (cnt < 127) & (beg+cnt < len) && |
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scanline[beg+cnt][i] == scanline[beg][i]; cnt++) |
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; |
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if (cnt >= MINRUN) |
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break; /* long enough */ |
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} |
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if ((beg-j > 1) & (beg-j < MINRUN)) { |
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c2 = j+1; |
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while (scanline[c2++][i] == scanline[j][i]) |
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if (c2 == beg) { /* short run */ |
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putc(128+beg-j, fp); |
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putc(scanline[j][i], fp); |
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j = beg; |
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break; |
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} |
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} |
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while (j < beg) { /* write out non-run */ |
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if ((c2 = beg-j) > 128) c2 = 128; |
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putc(c2, fp); |
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while (c2--) |
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putc(scanline[j++][i], fp); |
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} |
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if (cnt >= MINRUN) { /* write out run */ |
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putc(128+cnt, fp); |
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putc(scanline[beg][i], fp); |
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} else |
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cnt = 0; |
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} |
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} |
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return(ferror(fp) ? -1 : 0); |
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} |
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|
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/* |
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* An old-format scanline is either a stream of valid RGBE or XYZE real |
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* pixels or at least one real pixel followed by some number of |
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* invalid real pixels of the form (1,1,1,n), where n is a count. |
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* These can themselves be repeated to create a multibyte repeat |
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* count, with the least significant byte first (little-endian order.) |
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* Repeat counts are limited by the size of an int; if a repetition |
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* leads to an overrun, the rest of the the repetition will be |
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* silently ignored. |
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*/ |
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static int |
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oldreadcolrs( /* read in an old-style colr scanline */ |
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COLR *scanline, |
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int len, |
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FILE *fp |
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) |
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{ |
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int rshift = 0; |
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int i; |
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|
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while (len > 0) { |
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scanline[0][RED] = getc(fp); |
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scanline[0][GRN] = getc(fp); |
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scanline[0][BLU] = getc(fp); |
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scanline[0][EXP] = i = getc(fp); |
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if (i == EOF) |
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return(-1); |
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if (scanline[0][GRN] == 1 && |
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(scanline[0][RED] == 1) & |
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(scanline[0][BLU] == 1)) { |
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i = scanline[0][EXP] << rshift; |
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while (i--) { |
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copycolr(scanline[0], scanline[-1]); |
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if (--len <= 0) |
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return(0); |
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scanline++; |
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} |
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rshift += 8; |
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} else { |
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scanline++; |
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len--; |
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rshift = 0; |
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} |
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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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* There are two scanline formats: old and new. The old format |
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* compresses runs of RGBE or XYZE four-byte real pixels; the new |
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* format breaks the pixels into R, G, B, and E lines (or XYZE lines) |
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* which are individually run-length encoded. |
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* |
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* An old-format scanline always begins with a valid real pixel; at |
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* least one of the RGB (or XYZ) values will have its high-order bit |
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* set. A new-format scanline begins with four bytes which are not a |
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* valid real pixel: (2, 2, lenhigh, lenlow) where lenhigh is always |
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* less than 128 and hence never has a high-order bit set. |
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* |
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* A new-format scanline is broken into its RGBE or XYZE components. |
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* Each is output and run-length encoded separately so that a scanline |
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* is broken into four records. In turn, each record is organized |
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* into chunks of up to 128 characters, which begin with a count byte. |
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* If the count byte is greater than 128, the following data byte is |
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* repeated (count-128) times. If not, the count byte is followed by |
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* that many data bytes. |
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*/ |
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int |
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freadcolrs( /* read in an encoded colr scanline */ |
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COLR *scanline, |
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int len, |
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FILE *fp |
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) |
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{ |
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int i, j; |
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int code, val; |
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/* determine scanline type */ |
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if (len <= 0) |
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return(0); |
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if ((i = getc(fp)) == EOF) |
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return(-1); |
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scanline[0][RED] = i; |
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scanline[0][GRN] = getc(fp); |
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scanline[0][BLU] = getc(fp); |
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if ((i = getc(fp)) == EOF) |
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return(-1); |
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if ((scanline[0][RED] != 2) | (scanline[0][GRN] != 2) | |
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(scanline[0][BLU] & 0x80)) { |
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scanline[0][EXP] = i; |
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return(oldreadcolrs(scanline+1, len-1, fp)); |
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} |
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if ((scanline[0][BLU]<<8 | i) != len) |
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return(-1); /* length mismatch! */ |
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/* read each component */ |
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for (i = 0; i < 4; i++) |
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for (j = 0; j < len; ) { |
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if ((code = getc(fp)) == EOF) |
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return(-1); |
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if (code > 128) { /* run */ |
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code &= 127; |
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if ((val = getc(fp)) == EOF) |
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return -1; |
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if (j + code > len) |
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return -1; /* overrun */ |
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while (code--) |
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scanline[j++][i] = val; |
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} else { /* non-run */ |
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if (j + code > len) |
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return -1; /* overrun */ |
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while (code--) { |
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if ((val = getc(fp)) == EOF) |
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return -1; |
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scanline[j++][i] = val; |
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} |
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} |
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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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int |
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fwritescan( /* write out a scanline */ |
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COLOR *scanline, |
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int len, |
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FILE *fp |
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) |
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{ |
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COLR *clrscan; |
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int n; |
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COLR *sp; |
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/* get scanline buffer */ |
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if ((sp = (COLR *)tempbuffer(len*sizeof(COLR))) == NULL) |
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return(-1); |
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clrscan = sp; |
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/* convert scanline */ |
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n = len; |
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while (n-- > 0) { |
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setcolr(sp[0], scanline[0][RED], |
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scanline[0][GRN], |
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scanline[0][BLU]); |
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scanline++; |
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sp++; |
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} |
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return(fwritecolrs(clrscan, len, fp)); |
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} |
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|
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|
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int |
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freadscan( /* read in a scanline */ |
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COLOR *scanline, |
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int len, |
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FILE *fp |
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) |
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{ |
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COLR *clrscan; |
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|
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if ((clrscan = (COLR *)tempbuffer(len*sizeof(COLR))) == NULL) |
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return(-1); |
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if (freadcolrs(clrscan, len, fp) < 0) |
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return(-1); |
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/* convert scanline */ |
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colr_color(scanline[0], clrscan[0]); |
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while (--len > 0) { |
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scanline++; clrscan++; |
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if (clrscan[0][GRN] == clrscan[-1][GRN] && |
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(clrscan[0][RED] == clrscan[-1][RED]) & |
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(clrscan[0][BLU] == clrscan[-1][BLU]) & |
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(clrscan[0][EXP] == clrscan[-1][EXP])) |
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copycolor(scanline[0], scanline[-1]); |
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else |
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colr_color(scanline[0], clrscan[0]); |
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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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void |
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setcolr( /* assign a short color value */ |
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COLR clr, |
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double r, |
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double g, |
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double b |
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) |
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{ |
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double d; |
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int e; |
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|
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d = r > g ? r : g; |
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if (b > d) d = b; |
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|
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if (d <= 1e-32) { |
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clr[RED] = clr[GRN] = clr[BLU] = 0; |
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clr[EXP] = 0; |
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return; |
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} |
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|
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d = frexp(d, &e) * 256.0 / d; |
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|
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if (r > 0.0) |
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clr[RED] = r * d; |
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else |
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clr[RED] = 0; |
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if (g > 0.0) |
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clr[GRN] = g * d; |
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else |
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clr[GRN] = 0; |
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if (b > 0.0) |
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clr[BLU] = b * d; |
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else |
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clr[BLU] = 0; |
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|
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clr[EXP] = e + COLXS; |
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} |
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|
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|
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void |
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colr_color( /* convert short to float color */ |
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COLOR col, |
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COLR clr |
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) |
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{ |
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double f; |
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|
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if (clr[EXP] == 0) |
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col[RED] = col[GRN] = col[BLU] = 0.0; |
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else { |
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f = ldexp(1.0, (int)clr[EXP]-(COLXS+8)); |
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col[RED] = (clr[RED] + 0.5)*f; |
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col[GRN] = (clr[GRN] + 0.5)*f; |
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col[BLU] = (clr[BLU] + 0.5)*f; |
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} |
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} |
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|
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|
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int |
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bigdiff( /* c1 delta c2 > md? */ |
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COLOR c1, |
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COLOR c2, |
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double md |
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) |
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{ |
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int i; |
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|
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for (i = 0; i < 3; i++) |
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if (colval(c1,i)-colval(c2,i) > md*colval(c2,i) || |
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colval(c2,i)-colval(c1,i) > md*colval(c1,i)) |
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return(1); |
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return(0); |
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} |
