diff options
Diffstat (limited to 'editor/pnmpaste.c')
| -rw-r--r-- | editor/pnmpaste.c | 58 |
1 files changed, 34 insertions, 24 deletions
diff --git a/editor/pnmpaste.c b/editor/pnmpaste.c index 33834669..1e29d933 100644 --- a/editor/pnmpaste.c +++ b/editor/pnmpaste.c @@ -1,4 +1,4 @@ -/* pnmpaste.c - paste a rectangle into a portable anymap +/* pnmpaste.c - paste a rectangle into a PNM image ** ** Copyright (C) 1989 by Jef Poskanzer. ** @@ -21,7 +21,7 @@ enum boolOp {REPLACE, AND, OR, XOR /*, NAND, NOR, NXOR */ }; -struct cmdlineInfo { +struct CmdlineInfo { /* All the information the user supplied in the command line, in a form easy for the program to use. */ @@ -36,7 +36,7 @@ struct cmdlineInfo { static void parseCommandLine(int argc, const char ** argv, - struct cmdlineInfo * const cmdlineP) { + struct CmdlineInfo * const cmdlineP) { /*---------------------------------------------------------------------------- Note that the file spec array we return is stored in the storage that was passed to us as the argv array. @@ -65,7 +65,7 @@ parseCommandLine(int argc, const char ** argv, opt.short_allowed = FALSE; /* We have no short (old-fashioned) options */ opt.allowNegNum = TRUE; /* We have parms that are negative numbers */ - optParseOptions3(&argc, (char **)argv, opt, sizeof opt, 0); + pm_optParseOptions3(&argc, (char **)argv, opt, sizeof opt, 0); /* Uses and sets argc, argv, and some of *cmdlineP and others. */ if (replaceOpt + andOpt + orOpt + xorOpt > 1) @@ -108,7 +108,7 @@ static unsigned char leftBits(unsigned char const x, unsigned int const n){ /*---------------------------------------------------------------------------- - Clear rightmost (8-n) bits, retain leftmost (=high) n bits. + 'x' with the leftmost (high) n bits retained and the rest cleared to zero. -----------------------------------------------------------------------------*/ assert(n <= 8); @@ -121,7 +121,7 @@ static unsigned char rightBits(unsigned char const x, unsigned int const n){ /*---------------------------------------------------------------------------- - Return rightmost (=low) n bits of x. (Clear the rest). + The rightmost 'n' bits of 'x'. -----------------------------------------------------------------------------*/ assert(n <= 8); @@ -146,6 +146,12 @@ insertDirect(FILE * const ifP, 'buffer' is a scratch buffer for our use, at least wide enough to hold a packed PBM row of 'ifP'. -----------------------------------------------------------------------------*/ + /* We use pbm_readpbmrow_packed() to read whole bytes rounded up and merge + those into 'destrow', which means we update more than we're supposed to + if the image is not a multiple of 8 columns. In that case, we then fix + up the last byte by replacing the bits from the original image that we + messed up. + */ unsigned int const colBytes = pbm_packed_bytes(cols); unsigned int const last = colBytes - 1; unsigned char const origRight = destrow[last]; @@ -172,6 +178,10 @@ insertDirect(FILE * const ifP, } } + /* destrow[] now contains garbage in all but the cols % 8 leftmost bits of + the last byte we touched. Those are supposed to be unchanged from the + input, so we restore them now. + */ if (cols % 8 > 0) destrow[last] = leftBits(destrow[last], cols % 8) | rightBits(origRight, 8 - cols % 8); @@ -194,10 +204,10 @@ insertShift(FILE * const ifP, buffer[] is wide enough to hold a packed PBM row of *ifP plus one byte of margin. -----------------------------------------------------------------------------*/ - unsigned int const shiftBytes = pbm_packed_bytes(cols + offset); - unsigned int const last = shiftBytes - 1; - unsigned char const origLeft = destrow[0]; - unsigned char const origRight = destrow[last]; + unsigned int const shiftByteCt = pbm_packed_bytes(cols + offset); + unsigned int const last = shiftByteCt - 1; + unsigned char const origLeft = destrow[0]; + unsigned char const origRight = destrow[last]; unsigned int const padOffset = (cols + offset) % 8; @@ -209,7 +219,7 @@ insertShift(FILE * const ifP, /* Note that buffer[0] is undefined. */ - for (i = 0; i < shiftBytes; ++i) { + for (i = 0; i < shiftByteCt; ++i) { unsigned int const rsh = offset; unsigned int const lsh = 8-rsh; unsigned char const t = buffer[i] << lsh | buffer[i+1] >> rsh; @@ -227,9 +237,9 @@ insertShift(FILE * const ifP, } } - /* destrow[] now contains garbage in the 'offset' leftmost bits - and 8-offset rightmost bits. Those are supposed to be unchanged - from the input, so we restore them now. + /* destrow[] now contains garbage in the 'offset' leftmost bits and + 8-offset rightmost bits of the last byte we touched. Those are + supposed to be unchanged from the input, so we restore them now. */ destrow[0] = leftBits(origLeft, offset) | @@ -257,11 +267,11 @@ pastePbm(FILE * const fpInset, /*---------------------------------------------------------------------------- Fast paste for PBM -----------------------------------------------------------------------------*/ - unsigned char * const baserow = pbm_allocrow_packed(baseCols); - unsigned char * const buffer = pbm_allocrow_packed(insetCols+8); - int const shiftBytes = insertCol / 8; - unsigned int const shiftOffset = insertCol % 8; - int const baseColBytes = pbm_packed_bytes(baseCols); + unsigned char * const baserow = pbm_allocrow_packed(baseCols); + unsigned char * const buffer = pbm_allocrow_packed(insetCols+8); + unsigned int const shiftByteCt = insertCol / 8; + unsigned int const shiftOffset = insertCol % 8; + unsigned int const baseColByteCt = pbm_packed_bytes(baseCols); unsigned int row; @@ -272,16 +282,16 @@ pastePbm(FILE * const fpInset, if (row >= insertRow && row < insertRow + insetRows) { if (shiftOffset == 0) - insertDirect(fpInset, &baserow[shiftBytes], insetCols, + insertDirect(fpInset, &baserow[shiftByteCt], insetCols, insetFormat, operation, buffer); else - insertShift(fpInset, &baserow[shiftBytes], insetCols, + insertShift(fpInset, &baserow[shiftByteCt], insetCols, insetFormat, shiftOffset, operation, buffer); } if (baseCols % 8 > 0) - baserow[baseColBytes-1] - = leftBits(baserow[baseColBytes-1] , baseCols % 8); + baserow[baseColByteCt-1] + = leftBits(baserow[baseColByteCt-1] , baseCols % 8); pbm_writepbmrow_packed(stdout, baserow, baseCols, 0); } @@ -344,7 +354,7 @@ pasteNonPbm(FILE * const fpInset, int main(int argc, const char ** argv) { - struct cmdlineInfo cmdline; + struct CmdlineInfo cmdline; FILE * fpInset; FILE * fpBase; xelval maxvalInset, maxvalBase; |