shithub: riscv

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gif: fix color table clipping (for cb5.gif)

--- a/sys/src/cmd/jpg/readgif.c

+++ b/sys/src/cmd/jpg/readgif.c

@@ -376,7 +376,7 @@

 uchar*

 decode(Header *h, Rawimage *i, Entry *tbl)

 {

-	int c, doclip, incode, codesize, CTM, EOD, pici, datai, stacki, nbits, sreg, fc, code, piclen;

+	int c, incode, codesize, CTM, EOD, pici, datai, stacki, nbits, sreg, fc, code, piclen;

 	int csize, nentry, maxentry, first, ocode, ndata, nb;

 	uchar clip, *p, *pic;

 	uchar stack[4096], data[256];

@@ -386,10 +386,6 @@

 	codesize = h->buf[0];

 	if(codesize>8 || 0>codesize)

 		giferror(h, "ReadGIF: can't handle codesize %d", codesize);

-	doclip = 0;

-	if(i->cmap!=nil && i->cmaplen!=3*(1<<codesize)

-	  && (codesize!=2 || i->cmaplen!=3*2))			/* peculiar GIF bitmap files... */

-		doclip = 1;

 	CTM =1<<codesize;

 	EOD = CTM+1;

@@ -490,10 +486,10 @@

 	}

 Return:

-	if(doclip){

-		clip = i->cmaplen/3;

+	if(i->cmap!=nil && i->cmaplen!=3*256){

+		clip = (i->cmaplen/3)-1;

 		for(p = pic; p < pic+piclen; p++)

-			if(*p >= clip)

+			if(*p > clip)

 				*p = clip;

 	}

 	h->pic = nil;