+typedef uint32_t Pixcol;
+#define PSPIXCOL(priscan) priscan##32
+
+typedef struct {
+ Pixcol col;
+ struct OCRDatabaseNode *then;
+} OCRDatabaseLink;
+
+#define MAXGLYPHCHRS 3
+
+typedef struct OCRDatabaseNode {
+ char s[MAXGLYPHCHRS+1]; /* null-terminated; "" means no match here */
+ int nlinks, alinks;
+ OCRDatabaseLink *links;
+} OCRDatabaseNode;
+
+#define N_OCR_CONTEXTS 2
+static OCRDatabaseNode ocr_contexts[N_OCR_CONTEXTS];
+
+static void load_ocr_database(void) {
+ int ctx,nchrs;
+ OCRDatabaseNode *current, *additional;
+ char chrs[MAXGLYPHCHRS+1];
+ Pixcol cv;
+ int r,i,j;
+
+ FILE *db= fopen("database","r"); eassert(db);
+
+ for (;;) {
+ r= fscanf(db, "%d %d", &ctx, &nchrs);
+ if (r==EOF) break;
+ eassert(r==2);
+ eassert(ctx>=0 && ctx<N_OCR_CONTEXTS);
+ eassert(nchrs>0 && nchrs<=MAXGLYPHCHRS);
+
+ for (i=0; i<nchrs; i++) {
+ int c;
+ r= fscanf(db, "%x", &c); eassert(r==1);
+ eassert(c>0 && c<=255);
+ chrs[i]= c;
+ }
+ chrs[nchrs]= 0;
+
+ int twidth;
+ r= fscanf(db, "%d", &twidth); eassert(r==1);
+ current= &ocr_contexts[ctx];
+ for (i=0; i<twidth; i++) {
+ r= fscanf(db, "%"PSPIXCOL(SCNx), &cv); eassert(r==1);
+ for (j=0; j<current->nlinks; j++)
+ if (current->links[j].col == cv) {
+ current= current->links[j].then;
+ goto found_link;
+ }
+
+ additional= malloc(sizeof(*additional)); eassert(additional);
+ additional->s[0]= 0;
+ additional->nlinks= additional->alinks= 0;
+ additional->links= 0;
+ if (current->nlinks==current->alinks) {
+ current->alinks++;
+ current->alinks<<=1;
+ current->links= realloc(current->links,
+ sizeof(*current->links) * current->alinks);
+ eassert(current->links);
+ }
+ current->links[current->nlinks].col= cv;
+ current->links[current->nlinks].then= additional;
+ current->nlinks++;
+ current= additional;
+
+ found_link:;
+ }
+
+ eassert(!current->s[0]);
+ strcpy(current->s, chrs);
+ }
+ eassert(!ferror(db));
+ eassert(feof(db));
+ fclose(db);
+}
+
+static void ocr_rectangle(Rect r) {
+ int w= r.br.x - r.tl.x + 1;
+ int h= r.br.y - r.tl.y + 1;
+ Pixcol cols[w+1];
+ int x,y;
+ for (x=0; x<w; x++) {
+ Pixcol cx, rv;
+ for (y=0, cx=0, rv=1; y<h; y++, rv<<=1) {
+ switch (get(x+r.tl.x, y+r.tl.y)) {
+ case ' ': break;
+ case 'o': cx |= rv; break;
+ default: eassert(!"wrong pixel");
+ }
+ }
+ cols[x]= cx;
+ }
+ cols[w]= 0;
+
+ int nspaces=0;
+ int ctx=1,i;
+ x=0;
+
+ for (;;) {
+ if (x>w) break;
+
+ if (!cols[x]) {
+ nspaces++;
+ x++;
+ if (nspaces>3) ctx=1;
+ continue;
+ }
+
+ OCRDatabaseNode *current=0, *lastmatch=0;
+ int startx=x;
+ int afterlastmatchx=-1;
+ current= &ocr_contexts[ctx];
+ for (;;) {
+ if (x>w) break;
+ Pixcol cv= cols[x];
+ for (i=0; i<current->nlinks; i++)
+ if (current->links[i].col == cv)
+ goto found;
+ /* not found */
+ break;
+ found:
+ x++;
+ current= current->links[i].then;
+ if (current->s[0]) { lastmatch=current; afterlastmatchx=x; }
+ }
+
+ if (!lastmatch) {
+ int x2;
+ for (x2=x+1; x2<w && cols[x2]; x2++);
+ printf("UNKNOWN x=%d ctx=%d %d..%d\n",x, ctx, startx,x2);
+ x++;
+ } else {
+ printf("OUTPUT x=%d `%s'\n", x, lastmatch->s);
+ x= afterlastmatchx;
+ ctx= 0;
+ }
+ }
+}
+