ref: 57446af9a447c3a81414131f2407a9ca6f6a1a94
dir: /appl/grid/readjpg.b/
implement Readjpg;
include "sys.m";
sys: Sys;
include "draw.m";
draw: Draw;
Display, Image: import draw;
include "grid/readjpg.m";
display: ref Display;
slowread: int;
zeroints := array[64] of { * => 0 };
init(disp: ref Draw->Display)
{
sys = load Sys Sys->PATH;
draw = load Draw Draw->PATH;
display = disp;
init_tabs();
}
fjpg2img(fd: ref sys->FD, cachepath: string, chanin, chanout: chan of string): ref Image
{
if (fd == nil) return nil;
sync := chan of int;
imgchan := chan of ref Image;
is := newImageSource(0,0);
spawn slowreads(is,fd,cachepath, sync, chanout);
srpid := <- sync;
if (srpid == -1) return nil;
spawn getjpegimg(is, chanout, imgchan, sync);
gjipid := <- sync;
for (;;) alt {
ctl := <- chanin =>
if (ctl == "kill") {
if (srpid != -1) kill(srpid);
kill(gjipid);
return nil;
}
img := <- imgchan =>
if (srpid != -1) kill(srpid);
return img;
err := <- sync =>
if (err == 0) srpid = -1;
else {
kill(gjipid);
return nil;
}
}
}
jpg2img(filename, cachepath: string, chanin, chanout: chan of string): ref Image
{
fd := sys->open(filename, sys->OREAD);
return fjpg2img(fd, cachepath, chanin, chanout);
}
kill(pid: int)
{
pctl := sys->open("/prog/" + string pid + "/ctl", Sys->OWRITE);
if (pctl != nil)
sys->write(pctl, array of byte "kill", len "kill");
}
filelength(fd : ref sys->FD): int
{
(n, dir) := sys->fstat(fd);
if (n == -1) return -1;
filelen := int dir.length;
return filelen;
}
slowreads(is: ref ImageSource, fd : ref sys->FD, cachepath: string, sync: chan of int, chanout: chan of string)
{
filelen := filelength(fd);
if (filelen < 1) {
sync <-= -1;
return;
}
is.data = array[filelen] of byte;
slowread = 0;
sync <-= sys->pctl(0, nil);
cachefd : ref sys->FD = nil;
if (cachepath != "") cachefd = sys->create(cachepath, sys->OWRITE, 8r666);
if (chanout != nil) {
chanout <-= "l2 Loading...";
chanout <-= "pc 0";
}
i : int;
for (;;) {
i = sys->read(fd,is.data[slowread:], 8192);
if (i < 1) break;
if (cachefd != nil)
sys->write(cachefd, is.data[slowread:],i);
slowread += i;
if (chanout != nil)
chanout <-= "pc "+string ((slowread*100)/filelen);
sys->sleep(0);
}
if (i == -1 || slowread == 0) {
sync <-= -1;
return;
}
newdata := array[slowread] of byte;
newdata = is.data[:slowread];
is.data = newdata;
if (cachepath != "" && slowread < filelen)
sys->remove(cachepath);
sync <-= 0;
}
wait4data(n: int)
{
for(;;) {
if (slowread > n) break;
sys->sleep(100);
}
}
newImageSource(w, h: int) : ref ImageSource
{
is := ref ImageSource(
w,h, # width, height
0,0, # origw, origh
0, # i
nil, # jhdr
nil # data
);
return is;
}
getjpeghdr(is: ref ImageSource)
{
h := ref Jpegstate(
0, 0, # sr, cnt
0, # Nf
nil, # comp
byte 0, # mode,
0, 0, # X, Y
nil, # qt
nil, nil, # dcht, acht
0, # Ns
nil, # scomp
0, 0, # Ss, Se
0, 0, # Ah, Al
0, 0, # ri, nseg
nil, # nblock
nil, nil, # dccoeff, accoeff
0, 0, 0, 0 # nacross, ndown, Hmax, Vmax
);
is.jstate = h;
if(jpegmarker(is) != SOI)
sys->print("Error: Jpeg expected SOI marker\n");
(m, n) := jpegtabmisc(is);
if(!(m == SOF || m == SOF2))
sys->print("Error: Jpeg expected Frame marker");
nil = getc(is); # sample precision
h.Y = getbew(is);
h.X = getbew(is);
h.Nf = getc(is);
h.comp = array[h.Nf] of Framecomp;
h.nblock = array[h.Nf] of int;
for(i:=0; i<h.Nf; i++) {
h.comp[i].C = getc(is);
(H, V) := nibbles(getc(is));
h.comp[i].H = H;
h.comp[i].V = V;
h.comp[i].Tq = getc(is);
h.nblock[i] =H*V;
}
h.mode = byte m;
is.origw = h.X;
is.origh = h.Y;
setdims(is);
if(n != 6+3*h.Nf)
sys->print("Error: Jpeg bad SOF length");
}
setdims(is: ref ImageSource)
{
sw := is.origw;
sh := is.origh;
dw := is.width;
dh := is.height;
if(dw == 0 && dh == 0) {
dw = sw;
dh = sh;
}
else if(dw == 0 || dh == 0) {
if(dw == 0) {
dw = int ((real sw) * (real dh/real sh));
if(dw == 0)
dw = 1;
}
else {
dh = int ((real sh) * (real dw/real sw));
if(dh == 0)
dh = 1;
}
}
is.width = dw;
is.height = dh;
}
jpegmarker(is: ref ImageSource) : int
{
if(getc(is) != 16rFF)
sys->print("Error: Jpeg expected marker");
return getc(is);
}
getbew(is: ref ImageSource) : int
{
c0 := getc(is);
c1 := getc(is);
return (c0<<8) + c1;
}
getn(is: ref ImageSource, n: int) : (array of byte, int)
{
if (is.i + n > slowread - 1) wait4data(is.i + n);
a := is.data;
i := is.i;
if(i + n <= len a)
is.i += n;
# else
# sys->print("Error: premature eof");
return (a, i);
}
# Consume tables and miscellaneous marker segments,
# returning the marker id and length of the first non-such-segment
# (after having consumed the marker).
# May raise "premature eof" or other exception.
jpegtabmisc(is: ref ImageSource) : (int, int)
{
h := is.jstate;
m, n : int;
Loop:
for(;;) {
h.nseg++;
m = jpegmarker(is);
n = 0;
if(m != EOI)
n = getbew(is) - 2;
case m {
SOF or SOF2 or SOS or EOI =>
break Loop;
APPn+0 =>
if(h.nseg==1 && n >= 6) {
(buf, i) := getn(is, 6);
n -= 6;
if(string buf[i:i+4]=="JFIF") {
vers0 := int buf[i+5];
vers1 := int buf[i+6];
if(vers0>1 || vers1>2)
sys->print("Error: Jpeg unimplemented version");
}
}
APPn+1 to APPn+15 =>
;
DQT =>
jpegquanttables(is, n);
n = 0;
DHT =>
jpeghuffmantables(is, n);
n = 0;
DRI =>
h.ri =getbew(is);
n -= 2;
COM =>
;
* =>
sys->print("Error: Jpeg unexpected marker");
}
if(n > 0)
getn(is, n);
}
return (m, n);
}
# Consume huffman tables, raising exception on error.
jpeghuffmantables(is: ref ImageSource, n: int)
{
h := is.jstate;
if(h.dcht == nil) {
h.dcht = array[4] of ref Huffman;
h.acht = array[4] of ref Huffman;
}
for(l:= 0; l < n; )
l += jpeghuffmantable(is);
if(l != n)
sys->print("Error: Jpeg huffman table bad length");
}
jpeghuffmantable(is: ref ImageSource) : int
{
t := ref Huffman;
h := is.jstate;
(Tc, th) := nibbles(getc(is));
if(Tc > 1)
sys->print("Error: Jpeg unknown Huffman table class");
if(th>3 || (h.mode==byte SOF && th>1))
sys->print("Error: Jpeg unknown Huffman table index");
if(Tc == 0)
h.dcht[th] = t;
else
h.acht[th] = t;
# flow chart C-2
(b, bi) := getn(is, 16);
numcodes := array[16] of int;
nsize := 0;
for(i:=0; i<16; i++)
nsize += (numcodes[i] = int b[bi+i]);
t.size = array[nsize+1] of int;
k := 0;
for(i=1; i<=16; i++) {
n :=numcodes[i-1];
for(j:=0; j<n; j++)
t.size[k++] = i;
}
t.size[k] = 0;
# initialize HUFFVAL
t.val = array[nsize] of int;
(b, bi) = getn(is, nsize);
for(i=0; i<nsize; i++)
t.val[i] = int b[bi++];
# flow chart C-3
t.code = array[nsize+1] of int;
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
t.mincode = array[17] of int;
t.maxcode = array[17] of int;
t.valptr = array[17] of int;
i = 0;
j := 0;
F25:
for(;;) {
for(;;) {
i++;
if(i > 16)
break F25;
if(numcodes[i-1] != 0)
break;
t.maxcode[i] = -1;
}
t.valptr[i] = j;
t.mincode[i] = t.code[j];
j += int numcodes[i-1]-1;
t.maxcode[i] = t.code[j];
j++;
}
# create byte-indexed fast path tables
t.value = array[256] of int;
t.shift = array[256] of int;
maxcode := t.maxcode;
# stupid startup algorithm: just run machine for each byte value
Bytes:
for(v:=0; v<256; v++){
cnt := 7;
m := 1<<7;
code = 0;
sr := v;
i = 1;
for(;;i++){
if(sr & m)
code |= 1;
if(code <= maxcode[i])
break;
code <<= 1;
m >>= 1;
if(m == 0){
t.shift[v] = 0;
t.value[v] = -1;
continue Bytes;
}
cnt--;
}
t.shift[v] = 8-cnt;
t.value[v] = t.val[t.valptr[i]+(code-t.mincode[i])];
}
return nsize+17;
}
jpegquanttables(is: ref ImageSource, n: int)
{
h := is.jstate;
if(h.qt == nil)
h.qt = array[4] of array of int;
for(l:=0; l<n; )
l += jpegquanttable(is);
if(l != n)
sys->print("Error: Jpeg quant table bad length");
}
jpegquanttable(is: ref ImageSource): int
{
(pq, tq) := nibbles(getc(is));
if(pq > 1)
sys->print("Error: Jpeg unknown quantization table class");
if(tq > 3)
sys->print("Error: Jpeg bad quantization table index");
q := array[64] of int;
is.jstate.qt[tq] = q;
for(i:=0; i<64; i++) {
if(pq == 0)
q[i] =getc(is);
else
q[i] = getbew(is);
}
return 1+(64*(1+pq));;
}
# Have just read Frame header.
# Now expect:
# ((tabl/misc segment(s))* (scan header) (entropy coded segment)+)+ EOI
getjpegimg(is:ref ImageSource,chanout:chan of string,imgchan: chan of ref Image,sync: chan of int)
{
sync <-= sys->pctl(0, nil);
getjpeghdr(is);
h := is.jstate;
chans: array of array of byte = nil;
for(;;) {
(m, n) := jpegtabmisc(is);
if(m == EOI)
break;
if(m != SOS)
sys->print("Error: Jpeg expected start of scan");
h.Ns = getc(is);
scomp := array[h.Ns] of Scancomp;
for(i := 0; i < h.Ns; i++) {
scomp[i].C = getc(is);
(scomp[i].tdc, scomp[i].tac) = nibbles(getc(is));
}
h.scomp = scomp;
h.Ss = getc(is);
h.Se = getc(is);
(h.Ah, h.Al) = nibbles(getc(is));
if(n != 4+h.Ns*2)
sys->print("Error: Jpeg SOS header wrong length");
if(h.mode == byte SOF) {
if(chans != nil)
sys->print("Error: Jpeg baseline has > 1 scan");
chans = jpegbaselinescan(is, chanout);
}
}
if(chans == nil)
sys->print("Error: jpeg has no image");
width := is.width;
height := is.height;
if(width != h.X || height != h.Y) {
for(k := 0; k < len chans; k++)
chans[k] = resample(chans[k], h.X, h.Y, width, height);
}
r := remapYCbCr(chans, chanout);
im := newimage24(width, height);
im.writepixels(im.r, r);
imgchan <-= im;
}
newimage24(w, h: int) : ref Image
{
im := display.newimage(((0,0),(w,h)), Draw->RGB24, 0, Draw->White);
if(im == nil)
sys->print("Error: out of memory");
return im;
}
remapYCbCr(chans: array of array of byte, chanout: chan of string): array of byte
{
Y := chans[0];
Cb := chans[1];
Cr := chans[2];
rgb := array [3*len Y] of byte;
bix := 0;
lY := len Y;
n := lY / 20;
count := 0;
for (i := 0; i < lY; i++) {
if ((count == 0 || count >= n ) && chanout != nil) {
chanout <-= "l2 Processing...";
chanout <-= "pc "+string ((100*i)/ lY);
count = 0;
}
count++;
y := int Y[i];
cb := int Cb[i];
cr := int Cr[i];
r := y + Cr2r[cr];
g := y - Cr2g[cr] - Cb2g[cb];
b := y + Cb2b[cb];
rgb[bix++] = clampb[b+CLAMPBOFF];
rgb[bix++] = clampb[g+CLAMPBOFF];
rgb[bix++] = clampb[r+CLAMPBOFF];
}
if (chanout != nil) chanout <-= "pc 100";
return rgb;
}
zig := array[64] of {
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
};
jpegbaselinescan(is: ref ImageSource,chanout: chan of string) : array of array of byte
{
h := is.jstate;
Ns := h.Ns;
if(Ns != h.Nf)
sys->print("Error: Jpeg baseline needs Ns==Nf");
if(!(Ns==3 || Ns==1))
sys->print("Error: Jpeg baseline needs Ns==1 or 3");
chans := array[h.Nf] of array of byte;
for(k:=0; k<h.Nf; k++)
chans[k] = array[h.X*h.Y] of byte;
# build per-component arrays
Td := array[Ns] of int;
Ta := array[Ns] of int;
data := array[Ns] of array of array of int;
H := array[Ns] of int;
V := array[Ns] of int;
DC := array[Ns] of int;
# 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;
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
Td[comp] = h.scomp[comp].tdc;
Ta[comp] = h.scomp[comp].tac;
H[comp] = h.comp[comp].H;
V[comp] = h.comp[comp].V;
nblock := H[comp]*V[comp];
if(nblock != 1)
allHV1 = 0;
# data[comp]: needs (3+nblock)*4 + nblock*(3+8*8)*4 bytes
data[comp] = array[nblock] of array of int;
DC[comp] = 0;
for(m:=0; m<nblock; m++)
data[comp][m] = array[8*8] of int;
}
ri := h.ri;
h.cnt = 0;
h.sr = 0;
nacross := ((h.X+(8*Hmax-1))/(8*Hmax));
nmcu := ((h.Y+(8*Vmax-1))/(8*Vmax))*nacross;
n1 := 0;
n2 := nmcu / 20;
for(mcu:=0; mcu<nmcu; ) {
if ((n1 == 0 || n1 >= n2) && chanout != nil && slowread == len is.data) {
chanout <-= "l2 Scanning... ";
chanout <-= "pc "+string ((100*mcu)/nmcu);
n1 = 0;
}
n1 ++;
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 := jdecode(is, dcht);
diff := jreceive(is, t);
DC[comp] += diff;
# F-23
zz := data[comp][block];
zz[0:] = zeroints;
zz[0] = qt[0]*DC[comp];
k = 1;
for(;;) {
rs := jdecode(is, acht);
(rrrr, ssss) := nibbles(rs);
if(ssss == 0){
if(rrrr != 15)
break;
k += 16;
}else{
k += rrrr;
z := jreceive(is, ssss);
zz[zig[k]] = z*qt[k];
if(k == 63)
break;
k++;
}
}
idct(zz);
}
}
# rotate colors to RGB and assign to bytes
colormap(h, chans, 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){
jrestart(is, mcu);
for(comp=0; comp<Ns; comp++)
DC[comp] = 0;
}
}
if (chanout != nil) chanout <-= "pc 100";
return chans;
}
jrestart(is: ref ImageSource, mcu: int)
{
h := is.jstate;
ri := h.ri;
restart := mcu/ri-1;
rst, nskip: int;
nskip = 0;
do {
do{
rst = jnextborm(is);
nskip++;
}while(rst>=0 && rst!=16rFF);
if(rst == 16rFF){
rst = jnextborm(is);
nskip++;
}
} while(rst>=0 && (rst&~7)!= RST);
if(nskip != 2 || rst < 0 || ((rst&7) != (restart&7)))
sys->print("Error: Jpeg restart problem");
h.cnt = 0;
h.sr = 0;
}
jc1: con 2871; # 1.402 * 2048
jc2: con 705; # 0.34414 * 2048
jc3: con 1463; # 0.71414 * 2048
jc4: con 3629; # 1.772 * 2048
CLAMPBOFF: con 300;
NCLAMPB: con CLAMPBOFF+256+CLAMPBOFF;
CLAMPNOFF: con 64;
NCLAMPN: con CLAMPNOFF+256+CLAMPNOFF;
clampb: array of byte; # clamps byte values
init_tabs()
{
j: int;
clampb = array[NCLAMPB] of byte;
for(j=0; j<CLAMPBOFF; j++)
clampb[j] = byte 0;
for(j=0; j<256; j++)
clampb[CLAMPBOFF+j] = byte j;
for(j=0; j<CLAMPBOFF; j++)
clampb[CLAMPBOFF+256+j] = byte 16rFF;
}
# Fills in pixels (x,y) for x = minx=8*Hmax*(mcu%nacross), minx+1, ..., minx+8*Hmax-1 (or h.X-1, if less)
# and for y = miny=8*Vmax*(mcu/nacross), miny+1, ..., miny+8*Vmax-1 (or h.Y-1, if less)
colormap(h: ref Jpegstate, chans: array of array of byte, data0, data1, data2: array of array of int, mcu, nacross, Hmax, Vmax: int, H, V: array of int)
{
rpic := chans[0];
gpic := chans[1];
bpic := 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++) {
rpic[pici+x] = clampb[data0[b0][y0+x0++*H0/Hmax] + 128 + CLAMPBOFF];
gpic[pici+x] = clampb[data1[b1][y1+x1++*H1/Hmax] + 128 + CLAMPBOFF];
bpic[pici+x] = clampb[data2[b2][y2+x2++*H2/Hmax] + 128 + CLAMPBOFF];
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
jdecode(is: ref ImageSource, t: ref Huffman): int
{
h := is.jstate;
maxcode := t.maxcode;
if(h.cnt < 8)
jnextbyte(is);
# fast lookup
code := (h.sr>>(h.cnt-8))&16rFF;
v := t.value[code];
if(v >= 0){
h.cnt -= t.shift[code];
return v;
}
h.cnt -= 8;
if(h.cnt == 0)
jnextbyte(is);
h.cnt--;
cnt := h.cnt;
m := 1<<cnt;
sr := h.sr;
code <<= 1;
i := 9;
for(;;i++){
if(sr & m)
code |= 1;
if(code <= maxcode[i])
break;
code <<= 1;
m >>= 1;
if(m == 0){
sr = jnextbyte(is);
m = 16r80;
cnt = 8;
}
cnt--;
}
h.cnt = cnt;
return t.val[t.valptr[i]+(code-t.mincode[i])];
}
# load next byte of input
jnextbyte(is: ref ImageSource): int
{
b :=getc(is);
if(b == 16rFF) {
b2 :=getc(is);
if(b2 != 0) {
if(b2 == int DNL)
sys->print("Error: Jpeg DNL marker unimplemented");
# decoder is reading into marker; satisfy it and restore state
ungetc2(is, byte b);
}
}
h := is.jstate;
h.cnt += 8;
h.sr = (h.sr<<8)| b;
return b;
}
ungetc2(is: ref ImageSource, nil: byte)
{
if(is.i < 2) {
if(is.i != 1)
sys->print("Error: EXInternal: ungetc2 past beginning of buffer");
is.i = 0;
}
else
is.i -= 2;
}
getc(is: ref ImageSource) : int
{
if(is.i >= len is.data) {
sys->print("Error: premature eof");
}
if (is.i >= slowread)
wait4data(is.i);
return int is.data[is.i++];
}
# like jnextbyte, but look for marker too
jnextborm(is: ref ImageSource): int
{
b :=getc(is);
if(b == 16rFF)
return b;
h := is.jstate;
h.cnt += 8;
h.sr = (h.sr<<8)| b;
return b;
}
# return next s bits of input, MSB first, and level shift it
jreceive(is: ref ImageSource, s: int): int
{
h := is.jstate;
while(h.cnt < s)
jnextbyte(is);
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;
}
nibbles(c: int) : (int, int)
{
return (c>>4, c&15);
}
# 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
W1: con 2841; # 2048*sqrt(2)*cos(1*pi/16)
W2: con 2676; # 2048*sqrt(2)*cos(2*pi/16)
W3: con 2408; # 2048*sqrt(2)*cos(3*pi/16)
W5: con 1609; # 2048*sqrt(2)*cos(5*pi/16)
W6: con 1108; # 2048*sqrt(2)*cos(6*pi/16)
W7: con 565; # 2048*sqrt(2)*cos(7*pi/16)
W1pW7: con 3406; # W1+W7
W1mW7: con 2276; # W1-W7
W3pW5: con 4017; # W3+W5
W3mW5: con 799; # W3-W5
W2pW6: con 3784; # W2+W6
W2mW6: con 1567; # W2-W6
R2: con 181; # 256/sqrt(2)
idct(b: array of int)
{
# transform horizontally
for(y:=0; y<8; y++){
eighty := y<<3;
# if all non-DC components are zero, just propagate the DC term
if(b[eighty+1]==0)
if(b[eighty+2]==0 && b[eighty+3]==0)
if(b[eighty+4]==0 && b[eighty+5]==0)
if(b[eighty+6]==0 && b[eighty+7]==0){
v := b[eighty]<<3;
b[eighty+0] = v;
b[eighty+1] = v;
b[eighty+2] = v;
b[eighty+3] = v;
b[eighty+4] = v;
b[eighty+5] = v;
b[eighty+6] = v;
b[eighty+7] = v;
continue;
}
# prescale
x0 := (b[eighty+0]<<11)+128;
x1 := b[eighty+4]<<11;
x2 := b[eighty+6];
x3 := b[eighty+2];
x4 := b[eighty+1];
x5 := b[eighty+7];
x6 := b[eighty+5];
x7 := b[eighty+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
b[eighty+0] = (x7+x1)>>8;
b[eighty+1] = (x3+x2)>>8;
b[eighty+2] = (x0+x4)>>8;
b[eighty+3] = (x8+x6)>>8;
b[eighty+4] = (x8-x6)>>8;
b[eighty+5] = (x0-x4)>>8;
b[eighty+6] = (x3-x2)>>8;
b[eighty+7] = (x7-x1)>>8;
}
# transform vertically
for(x:=0; x<8; x++){
# if all non-DC components are zero, just propagate the DC term
if(b[x+8*1]==0)
if(b[x+8*2]==0 && b[x+8*3]==0)
if(b[x+8*4]==0 && b[x+8*5]==0)
if(b[x+8*6]==0 && b[x+8*7]==0){
v := (b[x+8*0]+32)>>6;
b[x+8*0] = v;
b[x+8*1] = v;
b[x+8*2] = v;
b[x+8*3] = v;
b[x+8*4] = v;
b[x+8*5] = v;
b[x+8*6] = v;
b[x+8*7] = v;
continue;
}
# prescale
x0 := (b[x+8*0]<<8)+8192;
x1 := b[x+8*4]<<8;
x2 := b[x+8*6];
x3 := b[x+8*2];
x4 := b[x+8*1];
x5 := b[x+8*7];
x6 := b[x+8*5];
x7 := b[x+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
b[x+8*0] = (x7+x1)>>14;
b[x+8*1] = (x3+x2)>>14;
b[x+8*2] = (x0+x4)>>14;
b[x+8*3] = (x8+x6)>>14;
b[x+8*4] = (x8-x6)>>14;
b[x+8*5] = (x0-x4)>>14;
b[x+8*6] = (x3-x2)>>14;
b[x+8*7] = (x7-x1)>>14;
}
}
resample(src: array of byte, sw, sh: int, dw, dh: int) : array of byte
{
if(src == nil || sw == 0 || sh == 0 || dw == 0 || dh == 0)
return src;
xfac := real sw / real dw;
yfac := real sh / real dh;
totpix := dw*dh;
dst := array[totpix] of byte;
dindex := 0;
# precompute index in src row corresponding to each index in dst row
sindices := array[dw] of int;
dx := 0.0;
for(x := 0; x < dw; x++) {
sx := int dx;
dx += xfac;
if(sx >= sw)
sx = sw-1;
sindices[x] = sx;
}
dy := 0.0;
for(y := 0; y < dh; y++) {
sy := int dy;
dy += yfac;
if(sy >= sh)
sy = sh-1;
soffset := sy * sw;
for(x = 0; x < dw; x++)
dst[dindex++] = src[soffset + sindices[x]];
}
return dst;
}
Cr2r := array [256] of {
-179, -178, -177, -175, -174, -172, -171, -170, -168, -167, -165, -164, -163, -161, -160, -158,
-157, -156, -154, -153, -151, -150, -149, -147, -146, -144, -143, -142, -140, -139, -137, -136,
-135, -133, -132, -130, -129, -128, -126, -125, -123, -122, -121, -119, -118, -116, -115, -114,
-112, -111, -109, -108, -107, -105, -104, -102, -101, -100, -98, -97, -95, -94, -93, -91,
-90, -88, -87, -86, -84, -83, -81, -80, -79, -77, -76, -74, -73, -72, -70, -69,
-67, -66, -64, -63, -62, -60, -59, -57, -56, -55, -53, -52, -50, -49, -48, -46,
-45, -43, -42, -41, -39, -38, -36, -35, -34, -32, -31, -29, -28, -27, -25, -24,
-22, -21, -20, -18, -17, -15, -14, -13, -11, -10, -8, -7, -6, -4, -3, -1,
0, 1, 3, 4, 6, 7, 8, 10, 11, 13, 14, 15, 17, 18, 20, 21,
22, 24, 25, 27, 28, 29, 31, 32, 34, 35, 36, 38, 39, 41, 42, 43,
45, 46, 48, 49, 50, 52, 53, 55, 56, 57, 59, 60, 62, 63, 64, 66,
67, 69, 70, 72, 73, 74, 76, 77, 79, 80, 81, 83, 84, 86, 87, 88,
90, 91, 93, 94, 95, 97, 98, 100, 101, 102, 104, 105, 107, 108, 109, 111,
112, 114, 115, 116, 118, 119, 121, 122, 123, 125, 126, 128, 129, 130, 132, 133,
135, 136, 137, 139, 140, 142, 143, 144, 146, 147, 149, 150, 151, 153, 154, 156,
157, 158, 160, 161, 163, 164, 165, 167, 168, 170, 171, 172, 174, 175, 177, 178,
};
Cr2g := array [256] of {
-91, -91, -90, -89, -89, -88, -87, -86, -86, -85, -84, -84, -83, -82, -81, -81,
-80, -79, -79, -78, -77, -76, -76, -75, -74, -74, -73, -72, -71, -71, -70, -69,
-69, -68, -67, -66, -66, -65, -64, -64, -63, -62, -61, -61, -60, -59, -59, -58,
-57, -56, -56, -55, -54, -54, -53, -52, -51, -51, -50, -49, -49, -48, -47, -46,
-46, -45, -44, -44, -43, -42, -41, -41, -40, -39, -39, -38, -37, -36, -36, -35,
-34, -34, -33, -32, -31, -31, -30, -29, -29, -28, -27, -26, -26, -25, -24, -24,
-23, -22, -21, -21, -20, -19, -19, -18, -17, -16, -16, -15, -14, -14, -13, -12,
-11, -11, -10, -9, -9, -8, -7, -6, -6, -5, -4, -4, -3, -2, -1, -1,
0, 1, 1, 2, 3, 4, 4, 5, 6, 6, 7, 8, 9, 9, 10, 11,
11, 12, 13, 14, 14, 15, 16, 16, 17, 18, 19, 19, 20, 21, 21, 22,
23, 24, 24, 25, 26, 26, 27, 28, 29, 29, 30, 31, 31, 32, 33, 34,
34, 35, 36, 36, 37, 38, 39, 39, 40, 41, 41, 42, 43, 44, 44, 45,
46, 46, 47, 48, 49, 49, 50, 51, 51, 52, 53, 54, 54, 55, 56, 56,
57, 58, 59, 59, 60, 61, 61, 62, 63, 64, 64, 65, 66, 66, 67, 68,
69, 69, 70, 71, 71, 72, 73, 74, 74, 75, 76, 76, 77, 78, 79, 79,
80, 81, 81, 82, 83, 84, 84, 85, 86, 86, 87, 88, 89, 89, 90, 91,
};
Cb2g := array [256] of {
-44, -44, -43, -43, -43, -42, -42, -42, -41, -41, -41, -40, -40, -40, -39, -39,
-39, -38, -38, -38, -37, -37, -36, -36, -36, -35, -35, -35, -34, -34, -34, -33,
-33, -33, -32, -32, -32, -31, -31, -31, -30, -30, -30, -29, -29, -29, -28, -28,
-28, -27, -27, -26, -26, -26, -25, -25, -25, -24, -24, -24, -23, -23, -23, -22,
-22, -22, -21, -21, -21, -20, -20, -20, -19, -19, -19, -18, -18, -18, -17, -17,
-17, -16, -16, -15, -15, -15, -14, -14, -14, -13, -13, -13, -12, -12, -12, -11,
-11, -11, -10, -10, -10, -9, -9, -9, -8, -8, -8, -7, -7, -7, -6, -6,
-6, -5, -5, -4, -4, -4, -3, -3, -3, -2, -2, -2, -1, -1, -1, 0,
0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5,
6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11,
11, 11, 12, 12, 12, 13, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16,
17, 17, 17, 18, 18, 18, 19, 19, 19, 20, 20, 20, 21, 21, 21, 22,
22, 22, 23, 23, 23, 24, 24, 24, 25, 25, 25, 26, 26, 26, 27, 27,
28, 28, 28, 29, 29, 29, 30, 30, 30, 31, 31, 31, 32, 32, 32, 33,
33, 33, 34, 34, 34, 35, 35, 35, 36, 36, 36, 37, 37, 38, 38, 38,
39, 39, 39, 40, 40, 40, 41, 41, 41, 42, 42, 42, 43, 43, 43, 44,
};
Cb2b := array [256] of {
-227, -225, -223, -222, -220, -218, -216, -214, -213, -211, -209, -207, -206, -204, -202, -200,
-198, -197, -195, -193, -191, -190, -188, -186, -184, -183, -181, -179, -177, -175, -174, -172,
-170, -168, -167, -165, -163, -161, -159, -158, -156, -154, -152, -151, -149, -147, -145, -144,
-142, -140, -138, -136, -135, -133, -131, -129, -128, -126, -124, -122, -120, -119, -117, -115,
-113, -112, -110, -108, -106, -105, -103, -101, -99, -97, -96, -94, -92, -90, -89, -87,
-85, -83, -82, -80, -78, -76, -74, -73, -71, -69, -67, -66, -64, -62, -60, -58,
-57, -55, -53, -51, -50, -48, -46, -44, -43, -41, -39, -37, -35, -34, -32, -30,
-28, -27, -25, -23, -21, -19, -18, -16, -14, -12, -11, -9, -7, -5, -4, -2,
0, 2, 4, 5, 7, 9, 11, 12, 14, 16, 18, 19, 21, 23, 25, 27,
28, 30, 32, 34, 35, 37, 39, 41, 43, 44, 46, 48, 50, 51, 53, 55,
57, 58, 60, 62, 64, 66, 67, 69, 71, 73, 74, 76, 78, 80, 82, 83,
85, 87, 89, 90, 92, 94, 96, 97, 99, 101, 103, 105, 106, 108, 110, 112,
113, 115, 117, 119, 120, 122, 124, 126, 128, 129, 131, 133, 135, 136, 138, 140,
142, 144, 145, 147, 149, 151, 152, 154, 156, 158, 159, 161, 163, 165, 167, 168,
170, 172, 174, 175, 177, 179, 181, 183, 184, 186, 188, 190, 191, 193, 195, 197,
198, 200, 202, 204, 206, 207, 209, 211, 213, 214, 216, 218, 220, 222, 223, 225,
};