ref: 7a503757b1251c2746df7bdcd891814c1518cc28
dir: /sys/src/cmd/jpg/writerawimage.c/
#include <u.h> #include <libc.h> #include <bio.h> #include <draw.h> #include "imagefile.h" /* * Hacked version for writing from Rawimage to file. * Assumes 8 bits per component. */ #define HSHIFT 3 /* HSHIFT==5 runs slightly faster, but hash table is 64x bigger */ #define NHASH (1<<(HSHIFT*NMATCH)) #define HMASK (NHASH-1) #define hupdate(h, c) ((((h)<<HSHIFT)^(c))&HMASK) typedef struct Hlist Hlist; struct Hlist{ uchar *s; Hlist *next, *prev; }; int writerawimage(int fd, Rawimage *i) { uchar *outbuf, *outp, *eout; /* encoded data, pointer, end */ uchar *loutp; /* start of encoded line */ Hlist *hash; /* heads of hash chains of past strings */ Hlist *chain, *hp; /* hash chain members, pointer */ Hlist *cp; /* next Hlist to fall out of window */ int h; /* hash value */ uchar *line, *eline; /* input line, end pointer */ uchar *data, *edata; /* input buffer, end pointer */ ulong n; /* length of input buffer */ int bpl; /* input line length */ int offs, runlen; /* offset, length of consumed data */ uchar dumpbuf[NDUMP]; /* dump accumulator */ int ndump; /* length of dump accumulator */ int ncblock; /* size of buffer */ Rectangle r; uchar *p, *q, *s, *es, *t; char hdr[11+5*12+1], buf[16]; ulong desc; r = i->r; switch(i->chandesc){ default: werrstr("can't handle chandesc %d", i->chandesc); return -1; case CY: bpl = Dx(r); desc = GREY8; break; case CYA16: bpl = 2*Dx(r); desc = CHAN2(CGrey, 8, CAlpha, 8); break; case CRGBV: bpl = Dx(r); desc = CMAP8; break; case CRGBVA16: bpl = 2*Dx(r); desc = CHAN2(CMap, 8, CAlpha, 8); break; case CRGB24: bpl = 3*Dx(r); desc = RGB24; break; case CRGBA32: bpl = 4*Dx(r); desc = RGBA32; break; } ncblock = _compblocksize(r, bpl/Dx(r)); outbuf = malloc(ncblock); hash = malloc(NHASH*sizeof(Hlist)); chain = malloc(NMEM*sizeof(Hlist)); if(outbuf == 0 || hash == 0 || chain == 0){ ErrOut: free(outbuf); free(hash); free(chain); return -1; } n = Dy(r)*bpl; data = i->chans[0]; sprint(hdr, "compressed\n%11s %11d %11d %11d %11d ", chantostr(buf, desc), r.min.x, r.min.y, r.max.x, r.max.y); if(write(fd, hdr, 11+5*12) != 11+5*12){ werrstr("i/o error writing header"); goto ErrOut; } edata = data+n; eout = outbuf+ncblock; line = data; r.max.y = r.min.y; while(line != edata){ memset(hash, 0, NHASH*sizeof(Hlist)); memset(chain, 0, NMEM*sizeof(Hlist)); cp = chain; h = 0; outp = outbuf; for(n = 0; n != NMATCH; n++) h = hupdate(h, line[n]); loutp = outbuf; while(line != edata){ ndump = 0; eline = line+bpl; for(p = line; p != eline; ){ if(eline-p < NRUN) es = eline; else es = p+NRUN; q = 0; runlen = 0; for(hp = hash[h].next; hp; hp = hp->next){ s = p + runlen; if(s >= es) continue; t = hp->s + runlen; for(; s >= p; s--) if(*s != *t--) goto matchloop; t += runlen+2; s += runlen+2; for(; s < es; s++) if(*s != *t++) break; n = s-p; if(n > runlen){ runlen = n; q = hp->s; if(n == NRUN) break; } matchloop: ; } if(runlen < NMATCH){ if(ndump == NDUMP){ if(eout-outp < ndump+1) goto Bfull; *outp++ = ndump-1+128; memmove(outp, dumpbuf, ndump); outp += ndump; ndump = 0; } dumpbuf[ndump++] = *p; runlen = 1; } else{ if(ndump != 0){ if(eout-outp < ndump+1) goto Bfull; *outp++ = ndump-1+128; memmove(outp, dumpbuf, ndump); outp += ndump; ndump = 0; } offs = p-q-1; if(eout-outp < 2) goto Bfull; *outp++ = ((runlen-NMATCH)<<2) + (offs>>8); *outp++ = offs&255; } for(q = p+runlen; p != q; p++){ if(cp->prev) cp->prev->next = 0; cp->next = hash[h].next; cp->prev = &hash[h]; if(cp->next) cp->next->prev = cp; cp->prev->next = cp; cp->s = p; if(++cp == &chain[NMEM]) cp = chain; if(edata-p > NMATCH) h = hupdate(h, p[NMATCH]); } } if(ndump != 0){ if(eout-outp < ndump+1) goto Bfull; *outp++ = ndump-1+128; memmove(outp, dumpbuf, ndump); outp += ndump; } line = eline; loutp = outp; r.max.y++; } Bfull: if(loutp == outbuf){ werrstr("compressor out of sync"); goto ErrOut; } n = loutp-outbuf; sprint(hdr, "%11d %11ld ", r.max.y, n); write(fd, hdr, 2*12); write(fd, outbuf, n); r.min.y = r.max.y; } free(outbuf); free(hash); free(chain); return 0; }