twriterawimage.c - plan9port - [fork] Plan 9 from user space
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twriterawimage.c (4584B)
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1 #include <u.h>
2 #include <libc.h>
3 #include <bio.h>
4 #include <draw.h>
5 #include "imagefile.h"
6
7 /*
8 * Hacked version for writing from Rawimage to file.
9 * Assumes 8 bits per component.
10 */
11
12 #define HSHIFT 3 /* HSHIFT==5 runs slightly faster, but hash table is 64x bigger */
13 #define NHASH (1<<(HSHIFT*NMATCH))
14 #define HMASK (NHASH-1)
15 #define hupdate(h, c) ((((h)<<HSHIFT)^(c))&HMASK)
16 typedef struct Hlist Hlist;
17 struct Hlist{
18 uchar *s;
19 Hlist *next, *prev;
20 };
21
22 int
23 writerawimage(int fd, Rawimage *i)
24 {
25 uchar *outbuf, *outp, *eout; /* encoded data, pointer, end */
26 uchar *loutp; /* start of encoded line */
27 Hlist *hash; /* heads of hash chains of past strings */
28 Hlist *chain, *hp; /* hash chain members, pointer */
29 Hlist *cp; /* next Hlist to fall out of window */
30 int h; /* hash value */
31 uchar *line, *eline; /* input line, end pointer */
32 uchar *data, *edata; /* input buffer, end pointer */
33 ulong n; /* length of input buffer */
34 int bpl; /* input line length */
35 int offs, runlen; /* offset, length of consumed data */
36 uchar dumpbuf[NDUMP]; /* dump accumulator */
37 int ndump; /* length of dump accumulator */
38 int ncblock; /* size of buffer */
39 Rectangle r;
40 uchar *p, *q, *s, *es, *t;
41 char hdr[11+5*12+1], buf[16];
42 ulong desc;
43
44 r = i->r;
45 switch(i->chandesc){
46 default:
47 werrstr("can't handle chandesc %d", i->chandesc);
48 return -1;
49 case CY:
50 bpl = Dx(r);
51 desc = GREY8;
52 break;
53 case CYA16:
54 bpl = 2*Dx(r);
55 desc = CHAN2(CGrey, 8, CAlpha, 8);
56 break;
57 case CRGBV:
58 bpl = Dx(r);
59 desc = CMAP8;
60 break;
61 case CRGBVA16:
62 bpl = 2*Dx(r);
63 desc = CHAN2(CMap, 8, CAlpha, 8);
64 break;
65 case CRGB24:
66 bpl = 3*Dx(r);
67 desc = RGB24;
68 break;
69 case CRGBA32:
70 bpl = 4*Dx(r);
71 desc = RGBA32;
72 break;
73 }
74 ncblock = _compblocksize(r, bpl/Dx(r));
75 outbuf = malloc(ncblock);
76 hash = malloc(NHASH*sizeof(Hlist));
77 chain = malloc(NMEM*sizeof(Hlist));
78 if(outbuf == 0 || hash == 0 || chain == 0){
79 ErrOut:
80 free(outbuf);
81 free(hash);
82 free(chain);
83 return -1;
84 }
85 n = Dy(r)*bpl;
86 data = i->chans[0];
87 sprint(hdr, "compressed\n%11s %11d %11d %11d %11d ",
88 chantostr(buf, desc), r.min.x, r.min.y, r.max.x, r.max.y);
89 if(write(fd, hdr, 11+5*12) != 11+5*12){
90 werrstr("i/o error writing header");
91 goto ErrOut;
92 }
93 edata = data+n;
94 eout = outbuf+ncblock;
95 line = data;
96 r.max.y = r.min.y;
97 while(line != edata){
98 memset(hash, 0, NHASH*sizeof(Hlist));
99 memset(chain, 0, NMEM*sizeof(Hlist));
100 cp = chain;
101 h = 0;
102 outp = outbuf;
103 for(n = 0; n != NMATCH; n++)
104 h = hupdate(h, line[n]);
105 loutp = outbuf;
106 while(line != edata){
107 ndump = 0;
108 eline = line+bpl;
109 for(p = line; p != eline; ){
110 if(eline-p < NRUN)
111 es = eline;
112 else
113 es = p+NRUN;
114 q = 0;
115 runlen = 0;
116 for(hp = hash[h].next; hp; hp = hp->next){
117 s = p + runlen;
118 if(s >= es)
119 continue;
120 t = hp->s + runlen;
121 for(; s >= p; s--)
122 if(*s != *t--)
123 goto matchloop;
124 t += runlen+2;
125 s += runlen+2;
126 for(; s < es; s++)
127 if(*s != *t++)
128 break;
129 n = s-p;
130 if(n > runlen){
131 runlen = n;
132 q = hp->s;
133 if(n == NRUN)
134 break;
135 }
136 matchloop: ;
137 }
138 if(runlen < NMATCH){
139 if(ndump == NDUMP){
140 if(eout-outp < ndump+1)
141 goto Bfull;
142 *outp++ = ndump-1+128;
143 memmove(outp, dumpbuf, ndump);
144 outp += ndump;
145 ndump = 0;
146 }
147 dumpbuf[ndump++] = *p;
148 runlen = 1;
149 }
150 else{
151 if(ndump != 0){
152 if(eout-outp < ndump+1)
153 goto Bfull;
154 *outp++ = ndump-1+128;
155 memmove(outp, dumpbuf, ndump);
156 outp += ndump;
157 ndump = 0;
158 }
159 offs = p-q-1;
160 if(eout-outp < 2)
161 goto Bfull;
162 *outp++ = ((runlen-NMATCH)<<2) + (offs>>8);
163 *outp++ = offs&255;
164 }
165 for(q = p+runlen; p != q; p++){
166 if(cp->prev)
167 cp->prev->next = 0;
168 cp->next = hash[h].next;
169 cp->prev = &hash[h];
170 if(cp->next)
171 cp->next->prev = cp;
172 cp->prev->next = cp;
173 cp->s = p;
174 if(++cp == &chain[NMEM])
175 cp = chain;
176 if(edata-p > NMATCH)
177 h = hupdate(h, p[NMATCH]);
178 }
179 }
180 if(ndump != 0){
181 if(eout-outp < ndump+1)
182 goto Bfull;
183 *outp++ = ndump-1+128;
184 memmove(outp, dumpbuf, ndump);
185 outp += ndump;
186 }
187 line = eline;
188 loutp = outp;
189 r.max.y++;
190 }
191 Bfull:
192 if(loutp == outbuf){
193 werrstr("compressor out of sync");
194 goto ErrOut;
195 }
196 n = loutp-outbuf;
197 sprint(hdr, "%11d %11ld ", r.max.y, n);
198 write(fd, hdr, 2*12);
199 write(fd, outbuf, n);
200 r.min.y = r.max.y;
201 }
202 free(outbuf);
203 free(hash);
204 free(chain);
205 return 0;
206 }