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|
implement Riff;
include "sys.m";
sys: Sys;
include "riff.m";
init()
{
sys = load Sys Sys->PATH;
}
open(file: string): (ref RD, string)
{
fd := sys->open(file, sys->OREAD);
if(fd == nil)
return (nil, "open failed");
r := ref RD;
r.fd = fd;
r.buf = array[DEFBUF] of byte;
r.ptr = 0;
r.nbyte = 0;
(hdr, l) := r.gethdr();
if(hdr != "RIFF")
return (nil, "not a RIFF file");
return (r, nil);
}
RD.gethdr(r: self ref RD): (string, int)
{
b := array[8] of byte;
if(r.readn(b, 8) != 8)
return (nil, -1);
return (string b[0:4], ledword(b, 4));
}
RD.check4(r: self ref RD, code: string): string
{
b := array[4] of byte;
if(r.readn(b, 4) != 4)
return "file i/o error";
if(string b != code)
return "bad four code header information";
return nil;
}
RD.avihdr(r: self ref RD): (ref AVIhdr, string)
{
(s, l) := r.gethdr();
if(s == nil || s != "avih")
return (nil, "missing/malformed avih");
b := array[AVImainhdr] of byte;
if(r.readn(b, AVImainhdr) != AVImainhdr)
return (nil, "short read in avih");
h := ref AVIhdr;
h.usecperframe = ledword(b, 0);
h.bytesec = ledword(b, 4);
h.flag = ledword(b, 12);
h.frames = ledword(b, 16);
h.initframes = ledword(b, 20);
h.streams = ledword(b, 24);
h.bufsize = ledword(b, 28);
h.width = ledword(b, 32);
h.height = ledword(b, 36);
return (h, nil);
}
RD.streaminfo(r: self ref RD): (ref AVIstream, string)
{
(h, l) := r.gethdr();
if(h != "LIST")
return (nil, "streaminfo expected LIST");
err := r.check4("strl");
if(err != nil)
return (nil, err);
(strh, sl) := r.gethdr();
if(strh != "strh")
return (nil, "streaminfo expected strh");
b := array[sl] of byte;
if(r.readn(b, sl) != sl)
return (nil, "streaminfo strl short read");
s := ref AVIstream;
s.stype = string b[0:4];
s.handler = string b[4:8];
s.flags = ledword(b, 8);
s.priority = ledword(b, 12);
s.initframes = ledword(b, 16);
s.scale = ledword(b, 20);
s.rate = ledword(b, 24);
s.start = ledword(b, 28);
s.length = ledword(b, 32);
s.bufsize = ledword(b, 36);
s.quality = ledword(b, 40);
s.samplesz = ledword(b, 44);
(strf, sf) := r.gethdr();
if(strf != "strf")
return (nil, "streaminfo expected strf");
s.fmt = array[sf] of byte;
if(r.readn(s.fmt, sf) != sf)
return (nil, "streaminfo strf short read");
return (s, nil);
}
RD.readn(r: self ref RD, b: array of byte, l: int): int
{
if(r.nbyte < l) {
c := 0;
if(r.nbyte != 0) {
b[0:] = r.buf[r.ptr:];
l -= r.nbyte;
c += r.nbyte;
b = b[r.nbyte:];
}
bsize := len r.buf;
while(l != 0) {
r.nbyte = sys->read(r.fd, r.buf, bsize);
if(r.nbyte <= 0) {
r.nbyte = 0;
return -1;
}
n := l;
if(n > bsize)
n = bsize;
r.ptr = 0;
b[0:] = r.buf[0:n];
b = b[n:];
r.nbyte -= n;
r.ptr += n;
l -= n;
c += n;
}
return c;
}
b[0:] = r.buf[r.ptr:r.ptr+l];
r.nbyte -= l;
r.ptr += l;
return l;
}
RD.skip(r: self ref RD, size: int): int
{
if(r.nbyte != 0) {
n := size;
if(n > r.nbyte)
n = r.nbyte;
r.ptr += n;
r.nbyte -= n;
size -= n;
if(size == 0)
return 0;
}
return int sys->seek(r.fd, big size, sys->SEEKRELA);
}
AVIstream.fmt2binfo(a: self ref AVIstream): string
{
if(len a.fmt < Binfosize)
return "format is wrong size for BITMAPINFO";
b := ref Bitmapinfo;
# Pull out the bitmap info
b.width = ledword(a.fmt, 4);
b.height = ledword(a.fmt, 8);
b.planes = leword(a.fmt, 12);
b.bitcount = leword(a.fmt, 14);
b.compression = ledword(a.fmt, 16);
b.sizeimage = ledword(a.fmt, 20);
b.xpelpermeter = ledword(a.fmt, 24);
b.ypelpermeter = ledword(a.fmt, 28);
b.clrused = ledword(a.fmt, 32);
b.clrimportant = ledword(a.fmt, 36);
# Parse out the color map
ncolor := len a.fmt - Binfosize;
if(ncolor & 3)
return "wrong size color map";
ncolor /= 4;
b.cmap = array[ncolor] of RGB;
idx := 40;
for(i := 0; i < ncolor; i++) {
b.cmap[i].r = int a.fmt[idx+2];
b.cmap[i].g = int a.fmt[idx+1];
b.cmap[i].b = int a.fmt[idx+0];
idx += 4;
}
a.fmt = nil;
a.binfo = b;
return nil;
}
leword(b: array of byte, o: int): int
{
return (int b[o+1] << 8) | int b[o];
}
ledword(b: array of byte, o: int): int
{
return (int b[o+3] << 24) |
(int b[o+2] << 16) |
(int b[o+1] << 8) |
int b[o];
}
|
