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/* $Id$ */

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/** @file 8bpp_optimized.cpp Implementation of the optimized 8 bpp blitter. */

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#include "../stdafx.h"

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#include "../zoom_func.h"

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#include "../debug.h"

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#include "../core/alloc_func.hpp"

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#include "../core/math_func.hpp"

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#include "8bpp_optimized.hpp"

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static FBlitter_8bppOptimized iFBlitter_8bppOptimized;

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void Blitter_8bppOptimized::Draw(Blitter::BlitterParams *bp, BlitterMode mode, ZoomLevel zoom)

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{

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	/* Find the offset of this zoom-level */

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	const SpriteData *sprite_src = (const SpriteData *)bp->sprite;

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	uint offset = sprite_src->offset[zoom];

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	/* Find where to start reading in the source sprite */

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	const uint8 *src = sprite_src->data + offset;

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	uint8 *dst_line = (uint8 *)bp->dst + bp->top * bp->pitch + bp->left;

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	/* Skip over the top lines in the source image */

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	for (int y = 0; y < bp->skip_top; y++) {

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		for (;;) {

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			uint trans = *src++;

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			uint pixels = *src++;

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			if (trans == 0 && pixels == 0) break;

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			src += pixels;

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		}

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	}

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	const uint8 *src_next = src;

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	for (int y = 0; y < bp->height; y++) {

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		uint8 *dst = dst_line;

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		dst_line += bp->pitch;

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		uint skip_left = bp->skip_left;

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		int width = bp->width;

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		for (;;) {

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			src = src_next;

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			uint trans = *src++;

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			uint pixels = *src++;

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			src_next = src + pixels;

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			if (trans == 0 && pixels == 0) break;

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			if (width <= 0) continue;

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			if (skip_left != 0) {

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				if (skip_left < trans) {

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					trans -= skip_left;

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					skip_left = 0;

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				} else {

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					skip_left -= trans;

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					trans = 0;

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				}

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				if (skip_left < pixels) {

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					src += skip_left;

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					pixels -= skip_left;

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					skip_left = 0;

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				} else {

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					src += pixels;

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					skip_left -= pixels;

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					pixels = 0;

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				}

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			}

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			if (skip_left != 0) continue;

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			/* Skip transparent pixels */

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			dst += trans;

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			width -= trans;

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			pixels = min<uint>(pixels, (uint)width);

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			width -= pixels;

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			switch (mode) {

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						dst++; src++;

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				default:

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					memcpy(dst, src, pixels);

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					dst += pixels; src += pixels;

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					break;

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			}

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		}

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	}

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}

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Sprite *Blitter_8bppOptimized::Encode(SpriteLoader::Sprite *sprite, Blitter::AllocatorProc *allocator)

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{

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	/* Make memory for all zoom-levels */

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	uint memory = sizeof(SpriteData);

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	for (ZoomLevel i = ZOOM_LVL_BEGIN; i < ZOOM_LVL_END; i++) {

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		memory += UnScaleByZoom(sprite->height, i) * UnScaleByZoom(sprite->width, i);

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	}

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	/* We have no idea how much memory we really need, so just guess something */

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	memory *= 5;

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	SpriteData *temp_dst = (SpriteData *)MallocT<byte>(memory);

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	byte *dst = temp_dst->data;

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	/* Make the sprites per zoom-level */

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	for (ZoomLevel i = ZOOM_LVL_BEGIN; i < ZOOM_LVL_END; i++) {

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		/* Store the index table */

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		uint offset = dst - temp_dst->data;

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		temp_dst->offset[i] = offset;

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		/* cache values, because compiler can't cache it */

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		int scaled_height = UnScaleByZoom(sprite->height, i);

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		int scaled_width  = UnScaleByZoom(sprite->width,  i);

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		int scaled_1      =   ScaleByZoom(1,              i);

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		for (int y = 0; y < scaled_height; y++) {

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			uint trans = 0;

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			uint pixels = 0;

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			uint last_colour = 0;

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			byte *count_dst = NULL;

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			/* Store the scaled image */

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			const SpriteLoader::CommonPixel *src = &sprite->data[ScaleByZoom(y, i) * sprite->width];

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			const SpriteLoader::CommonPixel *src_end = &src[sprite->width];

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			for (int x = 0; x < scaled_width; x++) {

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				uint colour = 0;

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				/* Get the color keeping in mind the zoom-level */

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				for (int j = 0; j < scaled_1; j++) {

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					if (src->m != 0) colour = src->m;

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					/* Because of the scaling it might happen we read outside the buffer. Avoid that. */

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					if (++src == src_end) break;

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				}

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				if (last_colour == 0 || colour == 0 || pixels == 255) {

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					if (count_dst != NULL) {

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						/* Write how many non-transparent bytes we get */

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						*count_dst = pixels;

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						pixels = 0;

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						count_dst = NULL;

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					}

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					/* As long as we find transparency bytes, keep counting */

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					if (colour == 0) {

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						last_colour = 0;

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						trans++;

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						continue;

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					}

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					/* No longer transparency, so write the amount of transparent bytes */

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					*dst = trans;

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					dst++;

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					trans = 0;

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					/* Reserve a byte for the pixel counter */

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					count_dst = dst;

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					dst++;

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				}

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				last_colour = colour;

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				pixels++;

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				*dst = colour;

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				dst++;

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			}

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			if (count_dst != NULL) *count_dst = pixels;

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			/* Write line-ending */

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			*dst = 0; dst++;

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			*dst = 0; dst++;

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		}

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	}

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	uint size = dst - (byte *)temp_dst;

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	/* Safety check, to make sure we guessed the size correctly */

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	assert(size < memory);

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	/* Allocate the exact amount of memory we need */

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	Sprite *dest_sprite = (Sprite *)allocator(sizeof(*dest_sprite) + size);

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	dest_sprite->height = sprite->height;

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	dest_sprite->width  = sprite->width;

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	dest_sprite->x_offs = sprite->x_offs;

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	dest_sprite->y_offs = sprite->y_offs;

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	memcpy(dest_sprite->data, temp_dst, size);

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	free(temp_dst);

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	return dest_sprite;

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}