ref: 26e00d014cebde8bc07725700b5ac9c0cade8171
dir: /sys/src/cmd/jpg/readjpg.c/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include <draw.h>
#include "imagefile.h"
enum {
/* Constants, all preceded by byte 0xFF */
SOF =0xC0, /* Start of Frame */
SOF2 =0xC2, /* Start of Frame; progressive Huffman */
JPG =0xC8, /* Reserved for JPEG extensions */
DHT =0xC4, /* Define Huffman Tables */
DAC =0xCC, /* Arithmetic coding conditioning */
RST =0xD0, /* Restart interval termination */
RST7 =0xD7, /* Restart interval termination (highest value) */
SOI =0xD8, /* Start of Image */
EOI =0xD9, /* End of Image */
SOS =0xDA, /* Start of Scan */
DQT =0xDB, /* Define quantization tables */
DNL =0xDC, /* Define number of lines */
DRI =0xDD, /* Define restart interval */
DHP =0xDE, /* Define hierarchical progression */
EXP =0xDF, /* Expand reference components */
APPn =0xE0, /* Reserved for application segments */
JPGn =0xF0, /* Reserved for JPEG extensions */
COM =0xFE, /* Comment */
CLAMPOFF = 300,
NCLAMP = CLAMPOFF+700
};
typedef struct Framecomp Framecomp;
typedef struct Header Header;
typedef struct Huffman Huffman;
struct Framecomp /* Frame component specifier from SOF marker */
{
int C;
int H;
int V;
int Tq;
};
struct Huffman
{
int *size; /* malloc'ed */
int *code; /* malloc'ed */
int *val; /* malloc'ed */
int mincode[17];
int maxcode[17];
int valptr[17];
/* fast lookup */
int value[256];
int shift[256];
};
struct Header
{
Biobuf *fd;
char err[256];
jmp_buf errlab;
/* variables in i/o routines */
int sr; /* shift register, right aligned */
int cnt; /* # bits in right part of sr */
uchar *buf;
int nbuf;
int peek;
int Nf;
Framecomp comp[3];
uchar mode;
int X;
int Y;
int qt[4][64]; /* quantization tables */
Huffman dcht[4];
Huffman acht[4];
int **data[3];
int ndata[3];
uchar *sf; /* start of frame; do better later */
uchar *ss; /* start of scan; do better later */
int ri; /* restart interval */
/* progressive scan */
Rawimage *image;
Rawimage **array;
int *dccoeff[3];
int **accoeff[3]; /* only need 8 bits plus quantization */
int naccoeff[3];
int nblock[3];
int nacross;
int ndown;
int Hmax;
int Vmax;
};
static uchar clamp[NCLAMP];
static Rawimage *readslave(Header*, int);
static int readsegment(Header*, int*);
static void quanttables(Header*, uchar*, int);
static void huffmantables(Header*, uchar*, int);
static void soiheader(Header*);
static int nextbyte(Header*, int);
static int int2(uchar*, int);
static void nibbles(int, int*, int*);
static int receive(Header*, int);
static int receiveEOB(Header*, int);
static int receivebit(Header*);
static void restart(Header*, int);
static int decode(Header*, Huffman*);
static Rawimage* baselinescan(Header*, int);
static void progressivescan(Header*, int);
static Rawimage* progressiveIDCT(Header*, int);
static void idct(int*);
static void colormap1(Header*, int, Rawimage*, int*, int, int);
static void colormapall1(Header*, int, Rawimage*, int*, int*, int*, int, int);
static void colormap(Header*, int, Rawimage*, int**, int**, int**, int, int, int, int, int*, int*);
static void jpgerror(Header*, char*, ...);
static char readerr[] = "ReadJPG: read error: %r";
static char memerr[] = "ReadJPG: malloc failed: %r";
static int zig[64] = {
0, 1, 8, 16, 9, 2, 3, 10, 17, /* 0-7 */
24, 32, 25, 18, 11, 4, 5, /* 8-15 */
12, 19, 26, 33, 40, 48, 41, 34, /* 16-23 */
27, 20, 13, 6, 7, 14, 21, 28, /* 24-31 */
35, 42, 49, 56, 57, 50, 43, 36, /* 32-39 */
29, 22, 15, 23, 30, 37, 44, 51, /* 40-47 */
58, 59, 52, 45, 38, 31, 39, 46, /* 48-55 */
53, 60, 61, 54, 47, 55, 62, 63 /* 56-63 */
};
static
void
jpginit(void)
{
int k;
static int inited;
if(inited)
return;
inited = 1;
for(k=0; k<CLAMPOFF; k++)
clamp[k] = 0;
for(; k<CLAMPOFF+256; k++)
clamp[k] = k-CLAMPOFF;
for(; k<NCLAMP; k++)
clamp[k] = 255;
}
static
void*
jpgmalloc(Header *h, int n, int clear)
{
void *p;
p = malloc(n);
if(p == nil)
jpgerror(h, memerr);
if(clear)
memset(p, 0, n);
return p;
}
static
void
clear(void **p)
{
if(*p){
free(*p);
*p = nil;
}
}
static
void
jpgfreeall(Header *h, int freeimage)
{
int i, j;
clear(&h->buf);
if(h->dccoeff[0])
for(i=0; i<3; i++)
clear(&h->dccoeff[i]);
if(h->accoeff[0])
for(i=0; i<3; i++){
if(h->accoeff[i])
for(j=0; j<h->naccoeff[i]; j++)
clear(&h->accoeff[i][j]);
clear(&h->accoeff[i]);
}
for(i=0; i<4; i++){
clear(&h->dcht[i].size);
clear(&h->acht[i].size);
clear(&h->dcht[i].code);
clear(&h->acht[i].code);
clear(&h->dcht[i].val);
clear(&h->acht[i].val);
}
if(h->data[0])
for(i=0; i<3; i++){
if(h->data[i])
for(j=0; j<h->ndata[i]; j++)
clear(&h->data[i][j]);
clear(&h->data[i]);
}
if(freeimage && h->image!=nil){
clear(&h->array);
clear(&h->image->cmap);
for(i=0; i<3; i++)
clear(&h->image->chans[i]);
clear(&h->image);
}
}
static
void
jpgerror(Header *h, char *fmt, ...)
{
va_list arg;
va_start(arg, fmt);
vseprint(h->err, h->err+sizeof h->err, fmt, arg);
va_end(arg);
if(h->image != nil)
fprint(2, "jpg: partial image: %s\n", h->err);
werrstr("%s", h->err);
longjmp(h->errlab, 1);
}
Rawimage**
Breadjpg(Biobuf *b, int colorspace)
{
Rawimage *r, **array;
Header *h;
char buf[ERRMAX];
buf[0] = '\0';
if(colorspace!=CYCbCr && colorspace!=CRGB){
errstr(buf, sizeof buf); /* throw it away */
werrstr("ReadJPG: unknown color space");
return nil;
}
jpginit();
h = malloc(sizeof(Header));
array = malloc(2*sizeof(Rawimage*));
if(h==nil || array==nil){
free(h);
free(array);
return nil;
}
h->array = array;
memset(h, 0, sizeof(Header));
h->fd = b;
errstr(buf, sizeof buf); /* throw it away */
if(setjmp(h->errlab))
r = h->image;
else
r = readslave(h, colorspace);
jpgfreeall(h, 0);
free(h);
array[0] = r;
array[1] = nil;
return array;
}
Rawimage**
readjpg(int fd, int colorspace)
{
Rawimage** a;
Biobuf b;
if(Binit(&b, fd, OREAD) < 0)
return nil;
a = Breadjpg(&b, colorspace);
Bterm(&b);
return a;
}
static
Rawimage*
readslave(Header *header, int colorspace)
{
Rawimage *image;
int nseg, i, H, V, m, n;
uchar *b;
soiheader(header);
nseg = 0;
image = nil;
header->buf = jpgmalloc(header, 4096, 0);
header->nbuf = 4096;
while(header->err[0] == '\0'){
nseg++;
n = readsegment(header, &m);
b = header->buf;
switch(m){
case -1:
return image;
case APPn+0:
if(nseg==1 && strncmp((char*)b, "JFIF", 4)==0) /* JFIF header; check version */
if(b[5]>1 || b[6]>2)
sprint(header->err, "ReadJPG: can't handle JFIF version %d.%2d", b[5], b[6]);
break;
case APPn+1: case APPn+2: case APPn+3: case APPn+4: case APPn+5:
case APPn+6: case APPn+7: case APPn+8: case APPn+9: case APPn+10:
case APPn+11: case APPn+12: case APPn+13: case APPn+14: case APPn+15:
break;
case DQT:
quanttables(header, b, n);
break;
case SOF:
case SOF2:
header->Y = int2(b, 1);
header->X = int2(b, 3);
header->Nf = b[5];
for(i=0; i<header->Nf; i++){
header->comp[i].C = b[6+3*i+0];
nibbles(b[6+3*i+1], &H, &V);
if(H<=0 || V<=0)
jpgerror(header, "non-positive sampling factor (Hsamp or Vsamp)");
/* hack: colormap1() doesnt handle resampling */
if(header->Nf == 1)
H = V = 1;
header->comp[i].H = H;
header->comp[i].V = V;
header->comp[i].Tq = b[6+3*i+2];
}
header->mode = m;
header->sf = b;
break;
case SOS:
header->ss = b;
switch(header->mode){
case SOF:
image = baselinescan(header, colorspace);
break;
case SOF2:
progressivescan(header, colorspace);
break;
default:
sprint(header->err, "unrecognized or unspecified encoding %d", header->mode);
break;
}
break;
case DHT:
huffmantables(header, b, n);
break;
case DRI:
header->ri = int2(b, 0);
break;
case COM:
break;
case EOI:
if(header->mode == SOF2)
image = progressiveIDCT(header, colorspace);
return image;
default:
sprint(header->err, "ReadJPG: unknown marker %.2x", m);
break;
}
}
return image;
}
/* readsegment is called after reading scan, which can have */
/* read ahead a byte. so we must check peek here */
static
int
readbyte(Header *h)
{
uchar x;
if(h->peek >= 0){
x = h->peek;
h->peek = -1;
}else if(Bread(h->fd, &x, 1) != 1)
jpgerror(h, readerr);
return x;
}
static
int
marker(Header *h)
{
int c;
Again:
while((c=readbyte(h)) == 0)
;
if(c != 0xFF)
goto Again;
while(c == 0xFF)
c = readbyte(h);
if(c == 0)
goto Again;
return c;
}
static
int
int2(uchar *buf, int n)
{
return (buf[n]<<8) + buf[n+1];
}
static
void
nibbles(int b, int *p0, int *p1)
{
*p0 = (b>>4) & 0xF;
*p1 = b & 0xF;
}
static
void
soiheader(Header *h)
{
h->peek = -1;
if(marker(h) != SOI)
jpgerror(h, "ReadJPG: unrecognized marker in header");
h->err[0] = '\0';
h->mode = 0;
h->ri = 0;
}
static
int
readsegment(Header *h, int *markerp)
{
int m, n;
uchar tmp[2];
if((m = marker(h)) == EOI){
*markerp = m;
return 0;
}
if(Bread(h->fd, tmp, 2) != 2)
Readerr:
jpgerror(h, readerr);
n = int2(tmp, 0);
if(n < 2)
goto Readerr;
n -= 2;
if(n > h->nbuf){
free(h->buf);
/* zero in case of short read later */
h->buf = jpgmalloc(h, n+1, 1); /* +1 for sentinel */
h->nbuf = n;
}
/* accept short reads to cope with some real-world jpegs */
if(Bread(h->fd, h->buf, n) < 0)
goto Readerr;
*markerp = m;
return n;
}
static
int
huffmantable(Header *h, uchar *b)
{
Huffman *t;
int Tc, th, n, nsize, i, j, k, v, cnt, code, si, sr;
int *maxcode;
nibbles(b[0], &Tc, &th);
if(Tc > 1)
jpgerror(h, "ReadJPG: unknown Huffman table class %d", Tc);
if(th>3 || (h->mode==SOF && th>1))
jpgerror(h, "ReadJPG: unknown Huffman table index %d", th);
if(Tc == 0)
t = &h->dcht[th];
else
t = &h->acht[th];
/* flow chart C-2 */
nsize = 0;
for(i=1; i<=16; i++)
nsize += b[i];
if(nsize == 0)
return 0;
t->size = jpgmalloc(h, (nsize+1)*sizeof(int), 1);
k = 0;
for(i=1; i<=16; i++){
n = b[i];
for(j=0; j<n; j++)
t->size[k++] = i;
}
t->size[k] = 0;
/* initialize HUFFVAL */
t->val = jpgmalloc(h, nsize*sizeof(int), 1);
for(i=0; i<nsize; i++)
t->val[i] = b[17+i];
/* flow chart C-3 */
t->code = jpgmalloc(h, (nsize+1)*sizeof(int), 1);
k = 0;
code = 0;
si = t->size[0];
for(;;){
do
t->code[k++] = code++;
while(t->size[k] == si);
if(t->size[k] == 0)
break;
do{
code <<= 1;
si++;
}while(t->size[k] != si);
}
/* flow chart F-25 */
i = 0;
j = 0;
for(;;){
for(;;){
i++;
if(i > 16)
goto outF25;
if(b[i] != 0)
break;
t->maxcode[i] = -1;
}
t->valptr[i] = j;
t->mincode[i] = t->code[j];
j += b[i]-1;
t->maxcode[i] = t->code[j];
j++;
}
outF25:
/* create byte-indexed fast path tables */
maxcode = t->maxcode;
/* stupid startup algorithm: just run machine for each byte value */
for(v=0; v<256; ){
code = 0;
cnt = 8;
sr = v;
for(i=1;;i++){
cnt--;
if(sr & (1<<cnt))
code |= 1;
if(code <= maxcode[i])
break;
code <<= 1;
if(cnt == 0){
t->shift[v] = 0;
t->value[v] = -1;
goto continueBytes;
}
}
t->shift[v] = 8-cnt;
t->value[v] = t->val[t->valptr[i]+(code-t->mincode[i])];
continueBytes:
v++;
}
return nsize;
}
static
void
huffmantables(Header *h, uchar *b, int n)
{
int l, mt;
for(l=0; l<n; l+=17+mt)
mt = huffmantable(h, &b[l]);
}
static
int
quanttable(Header *h, uchar *b)
{
int i, pq, tq, *q;
nibbles(b[0], &pq, &tq);
if(pq > 1)
jpgerror(h, "ReadJPG: unknown quantization table class %d", pq);
if(tq > 3)
jpgerror(h, "ReadJPG: unknown quantization table index %d", tq);
q = h->qt[tq];
for(i=0; i<64; i++){
if(pq == 0)
q[i] = b[1+i];
else
q[i] = int2(b, 1+2*i);
}
return 64*(1+pq);
}
static
void
quanttables(Header *h, uchar *b, int n)
{
int l, m;
for(l=0; l<n; l+=1+m)
m = quanttable(h, &b[l]);
}
static
Rawimage*
baselinescan(Header *h, int colorspace)
{
int Ns, z, k, m, Hmax, Vmax, comp;
int allHV1, nblock, ri, mcu, nacross, nmcu;
Huffman *dcht, *acht;
int block, t, diff, *qt;
uchar *ss;
Rawimage *image;
int Td[3], Ta[3], H[3], V[3], DC[3];
int ***data, *zz;
ss = h->ss;
Ns = ss[0];
if((Ns!=3 && Ns!=1) || Ns!=h->Nf)
jpgerror(h, "ReadJPG: can't handle scan not 1 or 3 components");
image = jpgmalloc(h, sizeof(Rawimage), 1);
h->image = image;
image->r = Rect(0, 0, h->X, h->Y);
image->cmap = nil;
image->cmaplen = 0;
image->chanlen = h->X*h->Y;
image->fields = 0;
image->gifflags = 0;
image->gifdelay = 0;
image->giftrindex = 0;
if(Ns == 3)
image->chandesc = colorspace;
else
image->chandesc = CY;
image->nchans = h->Nf;
for(k=0; k<h->Nf; k++)
image->chans[k] = jpgmalloc(h, h->X*h->Y, 0);
/* compute maximum H and V */
Hmax = 0;
Vmax = 0;
for(comp=0; comp<Ns; comp++){
if(h->comp[comp].H > Hmax)
Hmax = h->comp[comp].H;
if(h->comp[comp].V > Vmax)
Vmax = h->comp[comp].V;
}
/* initialize data structures */
allHV1 = 1;
data = h->data;
for(comp=0; comp<Ns; comp++){
/* JPEG requires scan components to be in same order as in frame, */
/* so if both have 3 we know scan is Y Cb Cr and there's no need to */
/* reorder */
nibbles(ss[2+2*comp], &Td[comp], &Ta[comp]);
H[comp] = h->comp[comp].H;
V[comp] = h->comp[comp].V;
nblock = H[comp]*V[comp];
if(nblock != 1)
allHV1 = 0;
data[comp] = jpgmalloc(h, nblock*sizeof(int*), 0);
h->ndata[comp] = nblock;
DC[comp] = 0;
for(m=0; m<nblock; m++)
data[comp][m] = jpgmalloc(h, 8*8*sizeof(int), 0);
}
ri = h->ri;
h->cnt = 0;
h->sr = 0;
h->peek = -1;
nacross = ((h->X+(8*Hmax-1))/(8*Hmax));
nmcu = ((h->Y+(8*Vmax-1))/(8*Vmax))*nacross;
for(mcu=0; mcu<nmcu; ){
for(comp=0; comp<Ns; comp++){
dcht = &h->dcht[Td[comp]];
acht = &h->acht[Ta[comp]];
qt = h->qt[h->comp[comp].Tq];
for(block=0; block<H[comp]*V[comp]; block++){
/* F-22 */
t = decode(h, dcht);
diff = receive(h, t);
DC[comp] += diff;
/* F-23 */
zz = data[comp][block];
memset(zz, 0, 8*8*sizeof(int));
zz[0] = qt[0]*DC[comp];
k = 1;
do{
t = decode(h, acht);
assert(t >= 0);
if((t&0x0F) == 0){
if((t&0xF0) != 0xF0)
break;
k += 16;
}else{
z = receive(h, t&0xF);
k += t>>4;
if(k >= 64)
break;
zz[zig[k]] = z*qt[k];
k++;
}
} while(k < 64);
idct(zz);
}
}
/* rotate colors to RGB and assign to bytes */
if(Ns == 1) /* very easy */
colormap1(h, colorspace, image, data[0][0], mcu, nacross);
else if(allHV1) /* fairly easy */
colormapall1(h, colorspace, image, data[0][0], data[1][0], data[2][0], mcu, nacross);
else /* miserable general case */
colormap(h, colorspace, image, data[0], data[1], data[2], mcu, nacross, Hmax, Vmax, H, V);
/* process restart marker, if present */
mcu++;
if(ri>0 && mcu<nmcu && mcu%ri==0){
restart(h, mcu);
for(comp=0; comp<Ns; comp++)
DC[comp] = 0;
}
}
return image;
}
static
void
restart(Header *h, int mcu)
{
int rest, rst, nskip;
rest = mcu/h->ri-1;
nskip = 0;
do{
do{
rst = nextbyte(h, 1);
nskip++;
}while(rst>=0 && rst!=0xFF);
if(rst == 0xFF){
rst = nextbyte(h, 1);
nskip++;
}
}while(rst>=0 && (rst&~7)!=RST);
if(nskip != 2)
sprint(h->err, "ReadJPG: skipped %d bytes at restart %d\n", nskip-2, rest);
if(rst < 0)
jpgerror(h, readerr);
if((rst&7) != (rest&7))
jpgerror(h, "ReadJPG: expected RST%d got %d", rest&7, rst&7);
h->cnt = 0;
h->sr = 0;
}
static
Rawimage*
progressiveIDCT(Header *h, int colorspace)
{
int k, m, comp, block, Nf, bn;
int allHV1, nblock, mcu, nmcu;
int H[3], V[3], blockno[3];
int *dccoeff, **accoeff;
int ***data, *zz;
Nf = h->Nf;
allHV1 = 1;
data = h->data;
for(comp=0; comp<Nf; comp++){
H[comp] = h->comp[comp].H;
V[comp] = h->comp[comp].V;
nblock = h->nblock[comp];
if(nblock != 1)
allHV1 = 0;
h->ndata[comp] = nblock;
data[comp] = jpgmalloc(h, nblock*sizeof(int*), 0);
for(m=0; m<nblock; m++)
data[comp][m] = jpgmalloc(h, 8*8*sizeof(int), 0);
}
memset(blockno, 0, sizeof blockno);
nmcu = h->nacross*h->ndown;
for(mcu=0; mcu<nmcu; mcu++){
for(comp=0; comp<Nf; comp++){
dccoeff = h->dccoeff[comp];
accoeff = h->accoeff[comp];
bn = blockno[comp];
for(block=0; block<h->nblock[comp]; block++){
zz = data[comp][block];
memset(zz, 0, 8*8*sizeof(int));
zz[0] = dccoeff[bn];
for(k=1; k<64; k++)
zz[zig[k]] = accoeff[bn][k];
idct(zz);
bn++;
}
blockno[comp] = bn;
}
/* rotate colors to RGB and assign to bytes */
if(Nf == 1) /* very easy */
colormap1(h, colorspace, h->image, data[0][0], mcu, h->nacross);
else if(allHV1) /* fairly easy */
colormapall1(h, colorspace, h->image, data[0][0], data[1][0], data[2][0], mcu, h->nacross);
else /* miserable general case */
colormap(h, colorspace, h->image, data[0], data[1], data[2], mcu, h->nacross, h->Hmax, h->Vmax, H, V);
}
return h->image;
}
static
void
progressiveinit(Header *h, int colorspace)
{
int Nf, Ns, j, k, nmcu, comp;
uchar *ss;
Rawimage *image;
ss = h->ss;
Ns = ss[0];
Nf = h->Nf;
if(Ns!=3 && Ns!=1)
jpgerror(h, "ReadJPG: image must have 1 or 3 components");
image = jpgmalloc(h, sizeof(Rawimage), 1);
h->image = image;
image->r = Rect(0, 0, h->X, h->Y);
image->cmap = nil;
image->cmaplen = 0;
image->chanlen = h->X*h->Y;
image->fields = 0;
image->gifflags = 0;
image->gifdelay = 0;
image->giftrindex = 0;
if(Nf == 3)
image->chandesc = colorspace;
else
image->chandesc = CY;
image->nchans = h->Nf;
for(k=0; k<Nf; k++){
image->chans[k] = jpgmalloc(h, h->X*h->Y, 0);
h->nblock[k] = h->comp[k].H*h->comp[k].V;
}
/* compute maximum H and V */
h->Hmax = 0;
h->Vmax = 0;
for(comp=0; comp<Nf; comp++){
if(h->comp[comp].H > h->Hmax)
h->Hmax = h->comp[comp].H;
if(h->comp[comp].V > h->Vmax)
h->Vmax = h->comp[comp].V;
}
h->nacross = ((h->X+(8*h->Hmax-1))/(8*h->Hmax));
h->ndown = ((h->Y+(8*h->Vmax-1))/(8*h->Vmax));
nmcu = h->nacross*h->ndown;
for(k=0; k<Nf; k++){
h->dccoeff[k] = jpgmalloc(h, h->nblock[k]*nmcu * sizeof(int), 1);
h->accoeff[k] = jpgmalloc(h, h->nblock[k]*nmcu * sizeof(int*), 1);
h->naccoeff[k] = h->nblock[k]*nmcu;
for(j=0; j<h->nblock[k]*nmcu; j++)
h->accoeff[k][j] = jpgmalloc(h, 64*sizeof(int), 1);
}
}
static
void
progressivedc(Header *h, int comp, int Ah, int Al)
{
int Ns, z, ri, mcu, nmcu;
int block, t, diff, qt, *dc, bn;
Huffman *dcht;
uchar *ss;
int i, Td[3], DC[3], blockno[3];
ss= h->ss;
Ns = ss[0];
if(Ns!=1 && Ns!=h->Nf)
jpgerror(h, "ReadJPG: can't handle progressive with Ns!=1 and Nf!=Ns in DC scan");
/* initialize data structures */
h->cnt = 0;
h->sr = 0;
h->peek = -1;
for(i=0; i<Ns; i++){
/*
* JPEG requires scan components to be in same order as in frame,
* so if both have 3 we know scan is Y Cb Cr and there's no need to
* reorder
*/
nibbles(ss[2+2*i], &Td[i], &z); /* z is ignored */
DC[i] = 0;
}
ri = h->ri;
nmcu = h->nacross*h->ndown;
memset(blockno, 0, sizeof blockno);
for(mcu=0; mcu<nmcu; ){
for(i=0; i<Ns; i++){
if(Ns != 1) comp = i;
dcht = &h->dcht[Td[i]];
qt = h->qt[h->comp[comp].Tq][0];
dc = h->dccoeff[comp];
bn = blockno[i];
for(block=0; block<h->nblock[comp]; block++){
if(Ah == 0){
t = decode(h, dcht);
diff = receive(h, t);
DC[i] += diff;
dc[bn] = qt*DC[i]<<Al;
}else
dc[bn] |= qt*receivebit(h)<<Al;
bn++;
}
blockno[i] = bn;
}
/* process restart marker, if present */
mcu++;
if(ri>0 && mcu<nmcu && mcu%ri==0){
restart(h, mcu);
for(i=0; i<Ns; i++)
DC[i] = 0;
}
}
}
static
void
progressiveac(Header *h, int comp, int Al)
{
int Ns, Ss, Se, z, k, eobrun, x, y, nver, tmcu, blockno, *acc, rs;
int ri, mcu, nacross, ndown, nmcu, nhor;
Huffman *acht;
int *qt, rrrr, ssss, q;
uchar *ss;
int Ta, H, V;
ss = h->ss;
Ns = ss[0];
if(Ns != 1)
jpgerror(h, "ReadJPG: illegal Ns>1 in progressive AC scan");
Ss = ss[1+2];
Se = ss[2+2];
H = h->comp[comp].H;
V = h->comp[comp].V;
nacross = h->nacross*H;
ndown = h->ndown*V;
q = 8*h->Hmax/H;
nhor = (h->X+q-1)/q;
q = 8*h->Vmax/V;
nver = (h->Y+q-1)/q;
/* initialize data structures */
h->cnt = 0;
h->sr = 0;
h->peek = -1;
nibbles(ss[1+1], &z, &Ta); /* z is thrown away */
ri = h->ri;
eobrun = 0;
acht = &h->acht[Ta];
qt = h->qt[h->comp[comp].Tq];
nmcu = nacross*ndown;
mcu = 0;
for(y=0; y<nver; y++){
for(x=0; x<nhor; x++){
/* Figure G-3 */
if(eobrun > 0){
--eobrun;
continue;
}
/* arrange blockno to be in same sequence as original scan calculation. */
tmcu = x/H + (nacross/H)*(y/V);
blockno = tmcu*H*V + H*(y%V) + x%H;
acc = h->accoeff[comp][blockno];
k = Ss;
do {
rs = decode(h, acht);
/* XXX remove rrrr ssss as in baselinescan */
nibbles(rs, &rrrr, &ssss);
if(ssss == 0){
if(rrrr < 15){
eobrun = 0;
if(rrrr > 0)
eobrun = receiveEOB(h, rrrr)-1;
break;
}
k += 16;
}else{
z = receive(h, ssss);
k += rrrr;
if(k > Se)
break;
acc[k] = z*qt[k]<<Al;
k++;
}
} while(k <= Se);
}
/* process restart marker, if present */
mcu++;
if(ri>0 && mcu<nmcu && mcu%ri==0){
restart(h, mcu);
eobrun = 0;
}
}
}
static
void
increment(Header *h, int acc[], int k, int Pt)
{
if(acc[k] == 0)
return;
if(receivebit(h) != 0)
if(acc[k] < 0)
acc[k] -= Pt;
else
acc[k] += Pt;
}
static
void
progressiveacinc(Header *h, int comp, int Al)
{
int Ns, i, z, k, Ss, Se, Ta, **ac, H, V;
int ri, mcu, nacross, ndown, nhor, nver, eobrun, nzeros, pending, x, y, tmcu, blockno, q, nmcu;
Huffman *acht;
int *qt, rrrr, ssss, *acc, rs;
uchar *ss;
ss = h->ss;
Ns = ss[0];
if(Ns != 1)
jpgerror(h, "ReadJPG: illegal Ns>1 in progressive AC scan");
Ss = ss[1+2];
Se = ss[2+2];
H = h->comp[comp].H;
V = h->comp[comp].V;
nacross = h->nacross*H;
ndown = h->ndown*V;
q = 8*h->Hmax/H;
nhor = (h->X+q-1)/q;
q = 8*h->Vmax/V;
nver = (h->Y+q-1)/q;
/* initialize data structures */
h->cnt = 0;
h->sr = 0;
h->peek = -1;
nibbles(ss[1+1], &z, &Ta); /* z is thrown away */
ri = h->ri;
eobrun = 0;
ac = h->accoeff[comp];
acht = &h->acht[Ta];
qt = h->qt[h->comp[comp].Tq];
nmcu = nacross*ndown;
mcu = 0;
pending = 0;
nzeros = -1;
for(y=0; y<nver; y++){
for(x=0; x<nhor; x++){
/* Figure G-7 */
/* arrange blockno to be in same sequence as original scan calculation. */
tmcu = x/H + (nacross/H)*(y/V);
blockno = tmcu*H*V + H*(y%V) + x%H;
acc = ac[blockno];
if(eobrun > 0){
if(nzeros > 0)
jpgerror(h, "ReadJPG: zeros pending at block start");
for(k=Ss; k<=Se; k++)
increment(h, acc, k, qt[k]<<Al);
--eobrun;
continue;
}
for(k=Ss; k<=Se; ){
if(nzeros >= 0){
if(acc[k] != 0)
increment(h, acc, k, qt[k]<<Al);
else if(nzeros-- == 0)
acc[k] = pending;
k++;
continue;
}
rs = decode(h, acht);
nibbles(rs, &rrrr, &ssss);
if(ssss == 0){
if(rrrr < 15){
eobrun = 0;
if(rrrr > 0)
eobrun = receiveEOB(h, rrrr)-1;
while(k <= Se){
increment(h, acc, k, qt[k]<<Al);
k++;
}
break;
}
for(i=0; i<16; k++){
increment(h, acc, k, qt[k]<<Al);
if(acc[k] == 0)
i++;
}
continue;
}else if(ssss != 1)
jpgerror(h, "ReadJPG: ssss!=1 in progressive increment");
nzeros = rrrr;
pending = receivebit(h);
if(pending == 0)
pending = -1;
pending *= qt[k]<<Al;
}
}
/* process restart marker, if present */
mcu++;
if(ri>0 && mcu<nmcu && mcu%ri==0){
restart(h, mcu);
eobrun = 0;
nzeros = -1;
}
}
}
static
void
progressivescan(Header *h, int colorspace)
{
uchar *ss;
int Ns, Ss, Ah, Al, c, comp, i;
if(h->dccoeff[0] == nil)
progressiveinit(h, colorspace);
ss = h->ss;
Ns = ss[0];
Ss = ss[1+2*Ns];
nibbles(ss[3+2*Ns], &Ah, &Al);
c = ss[1];
comp = -1;
for(i=0; i<h->Nf; i++)
if(h->comp[i].C == c)
comp = i;
if(comp == -1)
jpgerror(h, "ReadJPG: bad component index in scan header");
if(Ss == 0){
progressivedc(h, comp, Ah, Al);
return;
}
if(Ah == 0){
progressiveac(h, comp, Al);
return;
}
progressiveacinc(h, comp, Al);
}
enum {
c1 = 2871, /* 1.402 * 2048 */
c2 = 705, /* 0.34414 * 2048 */
c3 = 1463, /* 0.71414 * 2048 */
c4 = 3629, /* 1.772 * 2048 */
};
static
void
colormap1(Header *h, int colorspace, Rawimage *image, int data[8*8], int mcu, int nacross)
{
uchar *pic;
int x, y, dx, dy, minx, miny;
int r, k, pici;
USED(colorspace);
pic = image->chans[0];
minx = 8*(mcu%nacross);
dx = 8;
if(minx+dx > h->X)
dx = h->X-minx;
miny = 8*(mcu/nacross);
dy = 8;
if(miny+dy > h->Y)
dy = h->Y-miny;
pici = miny*h->X+minx;
k = 0;
for(y=0; y<dy; y++){
for(x=0; x<dx; x++){
r = clamp[(data[k+x]+128)+CLAMPOFF];
pic[pici+x] = r;
}
pici += h->X;
k += 8;
}
}
static
void
colormapall1(Header *h, int colorspace, Rawimage *image, int data0[8*8], int data1[8*8], int data2[8*8], int mcu, int nacross)
{
uchar *rpic, *gpic, *bpic, *rp, *gp, *bp;
int *p0, *p1, *p2;
int x, y, dx, dy, minx, miny;
int r, g, b, k, pici;
int Y, Cr, Cb;
rpic = image->chans[0];
gpic = image->chans[1];
bpic = image->chans[2];
minx = 8*(mcu%nacross);
dx = 8;
if(minx+dx > h->X)
dx = h->X-minx;
miny = 8*(mcu/nacross);
dy = 8;
if(miny+dy > h->Y)
dy = h->Y-miny;
pici = miny*h->X+minx;
k = 0;
for(y=0; y<dy; y++){
p0 = data0+k;
p1 = data1+k;
p2 = data2+k;
rp = rpic+pici;
gp = gpic+pici;
bp = bpic+pici;
if(colorspace == CYCbCr)
for(x=0; x<dx; x++){
*rp++ = clamp[*p0++ + 128 + CLAMPOFF];
*gp++ = clamp[*p1++ + 128 + CLAMPOFF];
*bp++ = clamp[*p2++ + 128 + CLAMPOFF];
}
else
for(x=0; x<dx; x++){
Y = (*p0++ + 128) << 11;
Cb = *p1++;
Cr = *p2++;
r = Y+c1*Cr;
g = Y-c2*Cb-c3*Cr;
b = Y+c4*Cb;
*rp++ = clamp[(r>>11)+CLAMPOFF];
*gp++ = clamp[(g>>11)+CLAMPOFF];
*bp++ = clamp[(b>>11)+CLAMPOFF];
}
pici += h->X;
k += 8;
}
}
static
void
colormap(Header *h, int colorspace, Rawimage *image, int *data0[8*8], int *data1[8*8], int *data2[8*8], int mcu, int nacross, int Hmax, int Vmax, int *H, int *V)
{
uchar *rpic, *gpic, *bpic;
int x, y, dx, dy, minx, miny;
int r, g, b, pici, H0, H1, H2;
int t, b0, b1, b2, y0, y1, y2, x0, x1, x2;
int Y, Cr, Cb;
rpic = image->chans[0];
gpic = image->chans[1];
bpic = image->chans[2];
minx = 8*Hmax*(mcu%nacross);
dx = 8*Hmax;
if(minx+dx > h->X)
dx = h->X-minx;
miny = 8*Vmax*(mcu/nacross);
dy = 8*Vmax;
if(miny+dy > h->Y)
dy = h->Y-miny;
pici = miny*h->X+minx;
H0 = H[0];
H1 = H[1];
H2 = H[2];
for(y=0; y<dy; y++){
t = y*V[0];
b0 = H0*(t/(8*Vmax));
y0 = 8*((t/Vmax)&7);
t = y*V[1];
b1 = H1*(t/(8*Vmax));
y1 = 8*((t/Vmax)&7);
t = y*V[2];
b2 = H2*(t/(8*Vmax));
y2 = 8*((t/Vmax)&7);
x0 = 0;
x1 = 0;
x2 = 0;
for(x=0; x<dx; x++){
if(colorspace == CYCbCr){
rpic[pici+x] = clamp[data0[b0][y0+x0++*H0/Hmax] + 128 + CLAMPOFF];
gpic[pici+x] = clamp[data1[b1][y1+x1++*H1/Hmax] + 128 + CLAMPOFF];
bpic[pici+x] = clamp[data2[b2][y2+x2++*H2/Hmax] + 128 + CLAMPOFF];
}else{
Y = (data0[b0][y0+x0++*H0/Hmax]+128)<<11;
Cb = data1[b1][y1+x1++*H1/Hmax];
Cr = data2[b2][y2+x2++*H2/Hmax];
r = Y+c1*Cr;
g = Y-c2*Cb-c3*Cr;
b = Y+c4*Cb;
rpic[pici+x] = clamp[(r>>11)+CLAMPOFF];
gpic[pici+x] = clamp[(g>>11)+CLAMPOFF];
bpic[pici+x] = clamp[(b>>11)+CLAMPOFF];
}
if(x0*H0/Hmax >= 8){
x0 = 0;
b0++;
}
if(x1*H1/Hmax >= 8){
x1 = 0;
b1++;
}
if(x2*H2/Hmax >= 8){
x2 = 0;
b2++;
}
}
pici += h->X;
}
}
/*
* decode next 8-bit value from entropy-coded input. chart F-26
*/
static
int
decode(Header *h, Huffman *t)
{
int code, v, cnt, sr, i;
int *maxcode;
maxcode = t->maxcode;
if(h->cnt < 8)
nextbyte(h, 0);
/* fast lookup */
code = (h->sr>>(h->cnt-8))&0xFF;
v = t->value[code];
if(v >= 0){
h->cnt -= t->shift[code];
return v;
}
h->cnt -= 8;
if(h->cnt == 0)
nextbyte(h, 0);
cnt = h->cnt;
sr = h->sr;
code <<= 1;
for(i = 9; i<17; i++){
cnt--;
if(sr & (1<<cnt))
code |= 1;
if(code <= maxcode[i])
break;
code <<= 1;
if(cnt == 0){
sr = nextbyte(h, 0);
cnt = 8;
}
}
if(i >= 17){
/* bad code */
code = 0;
i = 0;
}
h->cnt = cnt;
return t->val[t->valptr[i]+(code-t->mincode[i])];
}
/*
* load next byte of input
*/
static
int
nextbyte(Header *h, int marker)
{
int b, b2;
if(h->peek >= 0){
b = h->peek;
h->peek = -1;
}else{
b = Bgetc(h->fd);
if(b == Beof)
jpgerror(h, "truncated file");
b &= 0xFF;
}
if(b == 0xFF){
if(marker)
return b;
b2 = Bgetc(h->fd);
if(b2 != 0){
if(b2 == Beof)
jpgerror(h, "truncated file");
b2 &= 0xFF;
if(b2 == DNL)
jpgerror(h, "ReadJPG: DNL marker unimplemented");
/* decoder is reading into marker; satisfy it and restore state */
Bungetc(h->fd);
h->peek = b;
}
}
h->cnt += 8;
h->sr = (h->sr<<8) | b;
return b;
}
/*
* return next s bits of input, MSB first, and level shift it
*/
static
int
receive(Header *h, int s)
{
int v, m;
while(h->cnt < s)
nextbyte(h, 0);
h->cnt -= s;
v = h->sr >> h->cnt;
m = (1<<s);
v &= m-1;
/* level shift */
if(v < (m>>1))
v += ~(m-1)+1;
return v;
}
/*
* return next s bits of input, decode as EOB
*/
static
int
receiveEOB(Header *h, int s)
{
int v, m;
while(h->cnt < s)
nextbyte(h, 0);
h->cnt -= s;
v = h->sr >> h->cnt;
m = (1<<s);
v &= m-1;
/* level shift */
v += m;
return v;
}
/*
* return next bit of input
*/
static
int
receivebit(Header *h)
{
if(h->cnt < 1)
nextbyte(h, 0);
h->cnt--;
return (h->sr >> h->cnt) & 1;
}
/*
* Scaled integer implementation.
* inverse two dimensional DCT, Chen-Wang algorithm
* (IEEE ASSP-32, pp. 803-816, Aug. 1984)
* 32-bit integer arithmetic (8 bit coefficients)
* 11 mults, 29 adds per DCT
*
* coefficients extended to 12 bit for IEEE1180-1990 compliance
*/
enum {
W1 = 2841, /* 2048*sqrt(2)*cos(1*pi/16)*/
W2 = 2676, /* 2048*sqrt(2)*cos(2*pi/16)*/
W3 = 2408, /* 2048*sqrt(2)*cos(3*pi/16)*/
W5 = 1609, /* 2048*sqrt(2)*cos(5*pi/16)*/
W6 = 1108, /* 2048*sqrt(2)*cos(6*pi/16)*/
W7 = 565, /* 2048*sqrt(2)*cos(7*pi/16)*/
W1pW7 = 3406, /* W1+W7*/
W1mW7 = 2276, /* W1-W7*/
W3pW5 = 4017, /* W3+W5*/
W3mW5 = 799, /* W3-W5*/
W2pW6 = 3784, /* W2+W6*/
W2mW6 = 1567, /* W2-W6*/
R2 = 181 /* 256/sqrt(2)*/
};
static
void
idct(int b[8*8])
{
int x, y, eighty, v;
int x0, x1, x2, x3, x4, x5, x6, x7, x8;
int *p;
/* transform horizontally*/
for(y=0; y<8; y++){
eighty = y<<3;
/* if all non-DC components are zero, just propagate the DC term*/
p = b+eighty;
if(p[1]==0)
if(p[2]==0 && p[3]==0)
if(p[4]==0 && p[5]==0)
if(p[6]==0 && p[7]==0){
v = p[0]<<3;
p[0] = v;
p[1] = v;
p[2] = v;
p[3] = v;
p[4] = v;
p[5] = v;
p[6] = v;
p[7] = v;
continue;
}
/* prescale*/
x0 = (p[0]<<11)+128;
x1 = p[4]<<11;
x2 = p[6];
x3 = p[2];
x4 = p[1];
x5 = p[7];
x6 = p[5];
x7 = p[3];
/* first stage*/
x8 = W7*(x4+x5);
x4 = x8 + W1mW7*x4;
x5 = x8 - W1pW7*x5;
x8 = W3*(x6+x7);
x6 = x8 - W3mW5*x6;
x7 = x8 - W3pW5*x7;
/* second stage*/
x8 = x0 + x1;
x0 -= x1;
x1 = W6*(x3+x2);
x2 = x1 - W2pW6*x2;
x3 = x1 + W2mW6*x3;
x1 = x4 + x6;
x4 -= x6;
x6 = x5 + x7;
x5 -= x7;
/* third stage*/
x7 = x8 + x3;
x8 -= x3;
x3 = x0 + x2;
x0 -= x2;
x2 = (R2*(x4+x5)+128)>>8;
x4 = (R2*(x4-x5)+128)>>8;
/* fourth stage*/
p[0] = (x7+x1)>>8;
p[1] = (x3+x2)>>8;
p[2] = (x0+x4)>>8;
p[3] = (x8+x6)>>8;
p[4] = (x8-x6)>>8;
p[5] = (x0-x4)>>8;
p[6] = (x3-x2)>>8;
p[7] = (x7-x1)>>8;
}
/* transform vertically*/
for(x=0; x<8; x++){
/* if all non-DC components are zero, just propagate the DC term*/
p = b+x;
if(p[8*1]==0)
if(p[8*2]==0 && p[8*3]==0)
if(p[8*4]==0 && p[8*5]==0)
if(p[8*6]==0 && p[8*7]==0){
v = (p[8*0]+32)>>6;
p[8*0] = v;
p[8*1] = v;
p[8*2] = v;
p[8*3] = v;
p[8*4] = v;
p[8*5] = v;
p[8*6] = v;
p[8*7] = v;
continue;
}
/* prescale*/
x0 = (p[8*0]<<8)+8192;
x1 = p[8*4]<<8;
x2 = p[8*6];
x3 = p[8*2];
x4 = p[8*1];
x5 = p[8*7];
x6 = p[8*5];
x7 = p[8*3];
/* first stage*/
x8 = W7*(x4+x5) + 4;
x4 = (x8+W1mW7*x4)>>3;
x5 = (x8-W1pW7*x5)>>3;
x8 = W3*(x6+x7) + 4;
x6 = (x8-W3mW5*x6)>>3;
x7 = (x8-W3pW5*x7)>>3;
/* second stage*/
x8 = x0 + x1;
x0 -= x1;
x1 = W6*(x3+x2) + 4;
x2 = (x1-W2pW6*x2)>>3;
x3 = (x1+W2mW6*x3)>>3;
x1 = x4 + x6;
x4 -= x6;
x6 = x5 + x7;
x5 -= x7;
/* third stage*/
x7 = x8 + x3;
x8 -= x3;
x3 = x0 + x2;
x0 -= x2;
x2 = (R2*(x4+x5)+128)>>8;
x4 = (R2*(x4-x5)+128)>>8;
/* fourth stage*/
p[8*0] = (x7+x1)>>14;
p[8*1] = (x3+x2)>>14;
p[8*2] = (x0+x4)>>14;
p[8*3] = (x8+x6)>>14;
p[8*4] = (x8-x6)>>14;
p[8*5] = (x0-x4)>>14;
p[8*6] = (x3-x2)>>14;
p[8*7] = (x7-x1)>>14;
}
}