/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include	<u.h>#include	<libc.h>#include	<bio.h>#include	"sky.h" static void	qtree_expand(Biobuf*, uchar*, int, int, uchar*);static void	qtree_copy(uchar*, int, int, uchar*, int);static void	qtree_bitins(uchar*, int, int, Pix*, int, int);static void	read_bdirect(Biobuf*, Pix*, int, int, int, uchar*, int); voidqtree_decode(Biobuf *infile, Pix *a, int n, int nqx, int nqy, int nbitplanes){	int log2n, k, bit, b, nqmax;	int nx,ny,nfx,nfy,c;	int nqx2, nqy2;	unsigned char *scratch; 	/*	 * log2n is log2 of max(nqx,nqy) rounded up to next power of 2	 */	nqmax = nqy;	if(nqx > nqmax)		nqmax = nqx;	log2n = log(nqmax)/LN2+0.5;	if (nqmax > (1<<log2n))		log2n++; 	/*	 * allocate scratch array for working space	 */	nqx2 = (nqx+1)/2;	nqy2 = (nqy+1)/2;	scratch = (uchar*)malloc(nqx2*nqy2);	if(scratch == nil) {		fprint(2, "qtree_decode: insufficient memory\n");		exits("memory");	} 	/*	 * now decode each bit plane, starting at the top	 * A is assumed to be initialized to zero	 */	for(bit = nbitplanes-1; bit >= 0; bit--) {		/*		 * Was bitplane was quadtree-coded or written directly?		 */		b = input_nybble(infile);		if(b == 0) {			/*			 * bit map was written directly			 */			read_bdirect(infile, a, n, nqx, nqy, scratch, bit);		} else		if(b != 0xf) {			fprint(2, "qtree_decode: bad format code %x\n",b);			exits("format");		} else {			/*			 * bitmap was quadtree-coded, do log2n expansions			 * read first code			 */ 			scratch[0] = input_huffman(infile); 			/*			 * do log2n expansions, reading codes from file as necessary			 */			nx = 1;			ny = 1;			nfx = nqx;			nfy = nqy;			c = 1<<log2n;			for(k = 1; k<log2n; k++) {				/*				 * this somewhat cryptic code generates the sequence				 * n[k-1] = (n[k]+1)/2 where n[log2n]=nqx or nqy				 */				c = c>>1;				nx = nx<<1;				ny = ny<<1;				if(nfx <= c)					nx--;				else					nfx -= c;				if(nfy <= c)					ny--;				else					nfy -= c;				qtree_expand(infile, scratch, nx, ny, scratch);			} 			/*			 * copy last set of 4-bit codes to bitplane bit of array a			 */			qtree_bitins(scratch, nqx, nqy, a, n, bit);		}	}	free(scratch);} /* * do one quadtree expansion step on array a[(nqx+1)/2,(nqy+1)/2] * results put into b[nqx,nqy] (which may be the same as a) */staticvoidqtree_expand(Biobuf *infile, uchar *a, int nx, int ny, uchar *b){	uchar *b1; 	/*	 * first copy a to b, expanding each 4-bit value	 */	qtree_copy(a, nx, ny, b, ny); 	/*	 * now read new 4-bit values into b for each non-zero element	 */	b1 = &b[nx*ny];	while(b1 > b) {		b1--;		if(*b1 != 0)			*b1 = input_huffman(infile);	}} /* * copy 4-bit values from a[(nx+1)/2,(ny+1)/2] to b[nx,ny], expanding * each value to 2x2 pixels * a,b may be same array */staticvoidqtree_copy(uchar *a, int nx, int ny, uchar *b, int n){	int i, j, k, nx2, ny2;	int s00, s10; 	/*	 * first copy 4-bit values to b	 * start at end in case a,b are same array	 */	nx2 = (nx+1)/2;	ny2 = (ny+1)/2;	k = ny2*(nx2-1) + ny2-1;	/* k   is index of a[i,j] */	for (i = nx2-1; i >= 0; i--) {		s00 = 2*(n*i+ny2-1);	/* s00 is index of b[2*i,2*j] */		for (j = ny2-1; j >= 0; j--) {			b[s00] = a[k];			k -= 1;			s00 -= 2;		}	} 	/*	 * now expand each 2x2 block	 */	for(i = 0; i<nx-1; i += 2) {		s00 = n*i;				/* s00 is index of b[i,j] */		s10 = s00+n;				/* s10 is index of b[i+1,j] */		for(j = 0; j<ny-1; j += 2) {			b[s10+1] =  b[s00]     & 1;			b[s10  ] = (b[s00]>>1) & 1;			b[s00+1] = (b[s00]>>2) & 1;			b[s00  ] = (b[s00]>>3) & 1;			s00 += 2;			s10 += 2;		}		if(j < ny) {			/*			 * row size is odd, do last element in row			 * s00+1, s10+1 are off edge			 */			b[s10  ] = (b[s00]>>1) & 1;			b[s00  ] = (b[s00]>>3) & 1;		}	}	if(i < nx) {		/*		 * column size is odd, do last row		 * s10, s10+1 are off edge		 */		s00 = n*i;		for (j = 0; j<ny-1; j += 2) {			b[s00+1] = (b[s00]>>2) & 1;			b[s00  ] = (b[s00]>>3) & 1;			s00 += 2;		}		if(j < ny) {			/*			 * both row and column size are odd, do corner element			 * s00+1, s10, s10+1 are off edge			 */			b[s00  ] = (b[s00]>>3) & 1;		}	}} /* * Copy 4-bit values from a[(nx+1)/2,(ny+1)/2] to b[nx,ny], expanding * each value to 2x2 pixels and inserting into bitplane BIT of B. * A,B may NOT be same array (it wouldn't make sense to be inserting * bits into the same array anyway.) */staticvoidqtree_bitins(uchar *a, int nx, int ny, Pix *b, int n, int bit){	int i, j;	Pix *s00, *s10;	Pix px; 	/*	 * expand each 2x2 block	 */	for(i=0; i<nx-1; i+=2) {		s00 = &b[n*i];			/* s00 is index of b[i,j] */		s10 = s00+n;			/* s10 is index of b[i+1,j] */		for(j=0; j<ny-1; j+=2) {			px = *a++;			s10[1] |= ( px     & 1) << bit;			s10[0] |= ((px>>1) & 1) << bit;			s00[1] |= ((px>>2) & 1) << bit;			s00[0] |= ((px>>3) & 1) << bit;			s00 += 2;			s10 += 2;		}		if(j < ny) {			/*			 * row size is odd, do last element in row			 * s00+1, s10+1 are off edge			 */			px = *a++;			s10[0] |= ((px>>1) & 1) << bit;			s00[0] |= ((px>>3) & 1) << bit;		}	}	if(i < nx) {		/*		 * column size is odd, do last row		 * s10, s10+1 are off edge		 */		s00 = &b[n*i];		for(j=0; j<ny-1; j+=2) {			px = *a++;			s00[1] |= ((px>>2) & 1) << bit;			s00[0] |= ((px>>3) & 1) << bit;			s00 += 2;		}		if(j < ny) {			/*			 * both row and column size are odd, do corner element			 * s00+1, s10, s10+1 are off edge			 */			s00[0] |= ((*a>>3) & 1) << bit;		}	}} staticvoidread_bdirect(Biobuf *infile, Pix *a, int n, int nqx, int nqy, uchar *scratch, int bit){	int i; 	/*	 * read bit image packed 4 pixels/nybble	 */	for(i = 0; i < ((nqx+1)/2) * ((nqy+1)/2); i++) {		scratch[i] = input_nybble(infile);	} 	/*	 * insert in bitplane BIT of image A	 */	qtree_bitins(scratch, nqx, nqy, a, n, bit);}