#include <u.h>#include <libc.h>#include "pdf.h" /* 7.4.6 CCITTFaxDecode filter */ enum {	Tbyte = 1,	Tascii,	Tshort,	Tlong,	Trational, 	DImageWidth = 0,	DImageLength,	DBitsPerSample,	DCompression,	DPhotometricInterpretation,	DStripOffsets,	DRowsPerStrip,	DStripByteCounts,	Dcnt,}; #pragma pack ontypedef struct Entry Entry;typedef struct Header Header;typedef struct IFD IFD; struct Entry {	u16int tag;	u16int type;	u32int cnt;	u32int v;}; struct IFD {	u16int decnt;	Entry de[Dcnt];	u32int nextoff;}; /* TIFF header */struct Header {	u16int order;	u16int magic;	u32int ifd₀off;	IFD ifd; /* don't need more than one */};#pragma pack off static Header bh = {	.order = 0x4949, /* II, little endian */	.magic = 42,	.ifd₀off = 8,	.ifd = {		.decnt = Dcnt,		.de = {			[DImageWidth] = { 256, Tlong, 1, 0 },			[DImageLength] = { 257, Tlong, 1, 0 },			[DBitsPerSample] = { 258, Tshort, 1, 1 },			[DCompression] = { 259, Tshort, 1, 4 }, /* 4 ≡ ITU-T T.6 */			[DPhotometricInterpretation] = { 262, Tshort, 1, 0 }, /* 0 ≡ WhiteIsZero, 1 ≡ BlackIsZero */			[DStripOffsets] = { 273, Tlong, 1, sizeof(Header) },			[DRowsPerStrip] = { 278, Tlong, 1, 0 },			[DStripByteCounts] = { 279, Tlong, 1, 0 },		},		.nextoff = 0, /* last one */	},}; static intflreadall(void *aux, Buffer *bi, Buffer *bo){	Header *h; 	h = aux;	h->ifd.de[DStripByteCounts].v = bi->sz;	bufput(bo, (uchar*)h, sizeof(*h));	bufput(bo, bi->b, bi->sz);	bi->off = bi->sz; 	return 0;} static intflopen(Filter *f, Object *o){	Object *parms;	Header *h; 	if((h = malloc(sizeof(*h))) == nil)		return -1;	memmove(h, &bh, sizeof(bh));	parms = dictget(o, "DecodeParms");	h->ifd.de[DImageWidth].v = dictintopt(parms, "Columns", 1728);	h->ifd.de[DImageLength].v = dictint(parms, "Rows");	h->ifd.de[DPhotometricInterpretation].v = !dictint(parms, "BlackIs1");	h->ifd.de[DRowsPerStrip].v = h->ifd.de[DImageLength].v;	f->aux = h; 	return 0;} static voidflclose(Filter *f){	free(f->aux);} Filter filterCCITTFax = {	.name = "CCITTFaxDecode",	.readall = flreadall,	.open = flopen,	.close = flclose,};