/**
 ** BUILDAUX.C ---- generate and store a rotated character for a font
 **
 ** Copyright (c) 1995 Csaba Biegl, 820 Stirrup Dr, Nashville, TN 37221
 ** [e-mail: csaba@vuse.vanderbilt.edu] See "doc/copying.cb" for details.
 **/

#include "libgrx.h"
#include "allocate.h"
#include "arith.h"
#include "memfill.h"

char far *GrBuildAuxiliaryBitmap(GrFont *f,int chr,int dir,int ul)
{
	unsigned int idx = (unsigned int)chr - f->h.minchar;
	unsigned int bpos,rbpos,size,rsize,w,h;
	int  boff,rboff,rbinc;
	char far *stdmap,far *cvtmap;
	if(idx >= f->h.numchars) return(NULL);
	stdmap = &f->bitmap[f->chrinfo[idx].offset];
	dir = (dir & 3) + ((ul && (f->h.ulheight > 0)) ? 4 : 0);
	if(dir == GR_TEXT_RIGHT) return(stdmap);
	if(f->auxoffs[--dir] != NULL) {
	    unsigned int offs = f->auxoffs[dir][idx];
	    if(offs > 0) return(&f->auxmap[offs - 1]);
	}
	else {
	    size = sizeof(f->auxoffs[0][0]) * f->h.numchars;
	    f->auxoffs[dir] = farmalloc(size);
	    if(f->auxoffs[dir] == NULL) return(NULL);
	    memzero(f->auxoffs[dir],size);
	}
	h     = f->h.height;
	w     = f->chrinfo[idx].width;
	size  = h * (boff  = (w + 7) & ~7);
	rsize = w * (rboff = (h + 7) & ~7);
	switch(dir) {
	  case (GR_TEXT_RIGHT - 1 + 4):
	    rboff = boff;
	    rsize = size;
	    rbpos = 0;
	    rbinc = 1;
	    break;
	  case (GR_TEXT_DOWN - 1):              /* downward */
	  case (GR_TEXT_DOWN - 1 + 4):
	    rbpos = h - 1;
	    rbinc = rboff;
	    rboff = -1;
	    break;
	  case (GR_TEXT_LEFT - 1):              /* upside down, right to left */
	  case (GR_TEXT_LEFT - 1 + 4):
	    rboff = boff;
	    rsize = size;
	    rbpos = rsize - rboff + w - 1;
	    rbinc = -1;
	    rboff = -rboff;
	    break;
	  case (GR_TEXT_UP - 1):                /* upward */
	  case (GR_TEXT_UP - 1 + 4):
	    rbpos = rsize - rboff;
	    rbinc = -rboff;
	    rboff = 1;
	    break;
	  default:
	    return(NULL);
	}
	if((rsize >>= 3) == 0) return(NULL);
	if(rsize > (f->auxsize - f->auxnext)) {
	    /* add space for 32 (average) characters */
	    unsigned int newsize = (((f->h.width + 7) >> 3) * f->h.height) << 6;
	    newsize = umax(newsize,(rsize << 2));
	    newsize = umin(newsize,((unsigned int)(-4) - f->auxsize));
	    newsize += f->auxsize;
	    if(rsize > (newsize - f->auxnext)) return(NULL);
	    cvtmap = farmalloc(newsize);
	    if(cvtmap == NULL) return(NULL);
	    if(f->auxsize > 0) {
		memcpy(cvtmap,f->auxmap,f->auxsize);
		farfree(f->auxmap);
	    }
	    f->auxmap  = cvtmap;
	    f->auxsize = newsize;
	}
	cvtmap = &f->auxmap[f->auxnext];
	f->auxoffs[dir][idx] = f->auxnext + 1;
	f->auxnext += rsize;
	memfill_b(cvtmap,0,rsize);
	for(h = bpos = 0; bpos < size; bpos += boff,rbpos += rboff,h++) {
	    unsigned int bp    = bpos;
	    unsigned int bptop = bpos + w;
	    unsigned int rbp   = rbpos;
	    unsigned int ulrow = ul && ((h - f->h.ulpos) < f->h.ulheight);
	    for( ; bp < bptop; bp++,rbp += rbinc) {
		if(stdmap[bp >> 3] & (0x80 >> (bp & 7)) || ulrow) {
		    cvtmap[rbp >> 3] |= (0x80 >> (rbp & 7));
		}
	    }
	}
	return(cvtmap);
}