ref: df03eca7e7cbfadf1cf8c8c5a94390eaa5013a8b
dir: /appl/lib/riff.b/
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]; }