1 #include <u.h> 2 #include <libc.h> 3 #include <draw.h> 4 #include <memdraw.h> 5 6 #define CHUNK 8000 7 8 #define HSHIFT 3 /* HSHIFT==5 runs slightly faster, but hash table is 64x bigger */ 9 #define NHASH (1<<(HSHIFT*NMATCH)) 10 #define HMASK (NHASH-1) 11 #define hupdate(h, c) ((((h)<<HSHIFT)^(c))&HMASK) 12 typedef struct Hlist Hlist; 13 struct Hlist{ 14 uchar *s; 15 Hlist *next, *prev; 16 }; 17 18 int 19 writememimage(int fd, Memimage *i) 20 { 21 uchar *outbuf, *outp, *eout; /* encoded data, pointer, end */ 22 uchar *loutp; /* start of encoded line */ 23 Hlist *hash; /* heads of hash chains of past strings */ 24 Hlist *chain, *hp; /* hash chain members, pointer */ 25 Hlist *cp; /* next Hlist to fall out of window */ 26 int h; /* hash value */ 27 uchar *line, *eline; /* input line, end pointer */ 28 uchar *data, *edata; /* input buffer, end pointer */ 29 ulong n; /* length of input buffer */ 30 ulong nb; /* # of bytes returned by unloadimage */ 31 int bpl; /* input line length */ 32 int offs, runlen; /* offset, length of consumed data */ 33 uchar dumpbuf[NDUMP]; /* dump accumulator */ 34 int ndump; /* length of dump accumulator */ 35 int miny, dy; /* y values while unloading input */ 36 Rectangle r; 37 uchar *p, *q, *s, *es, *t; 38 char hdr[11+5*12+1]; 39 char cbuf[20]; 40 41 r = i->r; 42 bpl = bytesperline(r, i->depth); 43 n = Dy(r)*bpl; 44 data = malloc(n); 45 outbuf = malloc(NCBLOCK); 46 hash = malloc(NHASH*sizeof(Hlist)); 47 chain = malloc(NMEM*sizeof(Hlist)); 48 if(data == 0 || outbuf == 0 || hash == 0 || chain == 0){ 49 ErrOut: 50 free(data); 51 free(outbuf); 52 free(hash); 53 free(chain); 54 return -1; 55 } 56 for(miny = r.min.y; miny != r.max.y; miny += dy){ 57 dy = r.max.y-miny; 58 if(dy*bpl > CHUNK) 59 dy = CHUNK/bpl; 60 nb = unloadmemimage(i, Rect(r.min.x, miny, r.max.x, miny+dy), 61 data+(miny-r.min.y)*bpl, dy*bpl); 62 if(nb != dy*bpl) 63 goto ErrOut; 64 } 65 sprint(hdr, "compressed\n%11s %11d %11d %11d %11d ", 66 chantostr(cbuf, i->chan), r.min.x, r.min.y, r.max.x, r.max.y); 67 if(write(fd, hdr, 11+5*12) != 11+5*12) 68 goto ErrOut; 69 edata = data+n; 70 eout = outbuf+NCBLOCK; 71 line = data; 72 r.max.y = r.min.y; 73 while(line != edata){ 74 memset(hash, 0, NHASH*sizeof(Hlist)); 75 memset(chain, 0, NMEM*sizeof(Hlist)); 76 cp = chain; 77 h = 0; 78 outp = outbuf; 79 for(n = 0; n != NMATCH; n++) 80 h = hupdate(h, line[n]); 81 loutp = outbuf; 82 while(line != edata){ 83 ndump = 0; 84 eline = line+bpl; 85 for(p = line; p != eline; ){ 86 if(eline-p < NRUN) 87 es = eline; 88 else 89 es = p+NRUN; 90 q = 0; 91 runlen = 0; 92 for(hp = hash[h].next; hp; hp = hp->next){ 93 s = p + runlen; 94 if(s >= es) 95 continue; 96 t = hp->s + runlen; 97 for(; s >= p; s--) 98 if(*s != *t--) 99 goto matchloop; 100 t += runlen+2; 101 s += runlen+2; 102 for(; s < es; s++) 103 if(*s != *t++) 104 break; 105 n = s-p; 106 if(n > runlen){ 107 runlen = n; 108 q = hp->s; 109 if(n == NRUN) 110 break; 111 } 112 matchloop: ; 113 } 114 if(runlen < NMATCH){ 115 if(ndump == NDUMP){ 116 if(eout-outp < ndump+1) 117 goto Bfull; 118 *outp++ = ndump-1+128; 119 memmove(outp, dumpbuf, ndump); 120 outp += ndump; 121 ndump = 0; 122 } 123 dumpbuf[ndump++] = *p; 124 runlen = 1; 125 } 126 else{ 127 if(ndump != 0){ 128 if(eout-outp < ndump+1) 129 goto Bfull; 130 *outp++ = ndump-1+128; 131 memmove(outp, dumpbuf, ndump); 132 outp += ndump; 133 ndump = 0; 134 } 135 offs = p-q-1; 136 if(eout-outp < 2) 137 goto Bfull; 138 *outp++ = ((runlen-NMATCH)<<2) + (offs>>8); 139 *outp++ = offs&255; 140 } 141 for(q = p+runlen; p != q; p++){ 142 if(cp->prev) 143 cp->prev->next = 0; 144 cp->next = hash[h].next; 145 cp->prev = &hash[h]; 146 if(cp->next) 147 cp->next->prev = cp; 148 cp->prev->next = cp; 149 cp->s = p; 150 if(++cp == &chain[NMEM]) 151 cp = chain; 152 if(edata-p > NMATCH) 153 h = hupdate(h, p[NMATCH]); 154 } 155 } 156 if(ndump != 0){ 157 if(eout-outp < ndump+1) 158 goto Bfull; 159 *outp++ = ndump-1+128; 160 memmove(outp, dumpbuf, ndump); 161 outp += ndump; 162 } 163 line = eline; 164 loutp = outp; 165 r.max.y++; 166 } 167 Bfull: 168 if(loutp == outbuf) 169 goto ErrOut; 170 n = loutp-outbuf; 171 sprint(hdr, "%11d %11ld ", r.max.y, n); 172 write(fd, hdr, 2*12); 173 write(fd, outbuf, n); 174 r.min.y = r.max.y; 175 } 176 free(data); 177 free(outbuf); 178 free(hash); 179 free(chain); 180 return 0; 181 } 182