/* Copyright (c) 1990 Commodore-Amiga, Inc.
 *
 * This example is provided in electronic form by Commodore-Amiga, Inc. for
 * use with the 1.3 revisions of the Addison-Wesley Amiga reference manuals. 
 * The 1.3 Addison-Wesley Amiga Reference Manual series contains additional
 * information on the correct usage of the techniques and operating system
 * functions presented in this example.  The source and executable code of
 * this example may only be distributed in free electronic form, via bulletin
 * board or as part of a fully non-commercial and freely redistributable
 * diskette.  Both the source and executable code (including comments) must
 * be included, without modification, in any copy.  This example may not be
 * published in printed form or distributed with any commercial product.
 * However, the programming techniques and support routines set forth in
 * this example may be used in the development of original executable
 * software products for Commodore Amiga computers.
 * All other rights reserved.
 * This example is provided "as-is" and is subject to change; no warranties
 * are made.  All use is at your own risk.  No liability or responsibility
 * is assumed.
 */

#include <exec/types.h>
#include <devices/prtgfx.h>

Transfer(PInfo, y, ptr)
struct PrtInfo *PInfo;
UWORD y;	/* row # */
UBYTE *ptr;	/* ptr to buffer */
{
	static UBYTE bit_table[] = {128, 64, 32, 16, 8, 4, 2, 1};
	UBYTE *dmatrix, Black, dvalue, threshold;
	union colorEntry *ColorInt;
	UWORD x, width, sx, *sxptr, bit;

	/* pre-compute */
	/* printer non-specific, MUST DO FOR EVERY PRINTER */
	x = PInfo->pi_xpos; /* get starting x position */
	ColorInt = PInfo->pi_ColorInt; /* get ptr to color intensities */
	sxptr = PInfo->pi_ScaleX;
	width = PInfo->pi_width; /* get # of source pixels */

	/* pre-compute threshold; are we thresholding? */
	if (threshold = PInfo->pi_threshold) { /* thresholding */
		dvalue = threshold ^ 15; /* yes, so pre-compute dither value */
		do { /* for all source pixels */
			/* pre-compute intensity value for Black */
			Black = ColorInt->colorByte[PCMBLACK];
			ColorInt++; /* bump ptr for next time */

			sx = *sxptr++;

			/* dither and render pixel */
			do { /* use this pixel 'sx' times */
				/* if we should render Black */
				if (Black > dvalue) {
					/* set bit */
					*(ptr + (x >> 3)) |= bit_table[x & 7];
				}
				++x; /* done 1 more printer pixel */
			} while (--sx);
		} while (--width);
	}
	else { /* not thresholding, pre-compute ptr to dither matrix */
		dmatrix = PInfo->pi_dmatrix + ((y & 3) << 2);
		do { /* for all source pixels */
			/* pre-compute intensity value for Black */
			Black = ColorInt->colorByte[PCMBLACK];
			ColorInt++; /* bump ptr for next time */

			sx = *sxptr++;

			/* dither and render pixel */
			do { /* use this pixel 'sx' times */
				/* if we should render Black */
				if (Black > dmatrix[x & 3]) {
					/* set bit */
					*(ptr + (x >> 3)) |= bit_table[x & 7];
				}
				++x; /* done 1 more printer pixel */
			} while (--sx);
		} while (--width);
	}
}