Create hash based damage checker

include/damage-refinery.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <stdint.h>
+
+struct pixman_region16;
+struct wv_buffer;
+
+struct damage_refinery {
+	uint32_t* hashes;
+	uint32_t width;
+	uint32_t height;
+};
+
+int damage_refinery_init(struct damage_refinery* self, uint32_t width,
+		uint32_t height);
+void damage_refinery_destroy(struct damage_refinery* self);
+
+void damage_refine(struct damage_refinery* self,
+		struct pixman_region16* refined, 
+		struct pixman_region16* hint,
+		const struct wv_buffer* buffer);

include/murmurhash.h

@@ -0,0 +1,48 @@
+/*
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2014 Joseph Werle
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef MURMURHASH_H
+#define MURMURHASH_H 1
+
+#include <stdint.h>
+
+#define MURMURHASH_VERSION "0.0.3"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Returns a murmur hash of `key' based on `seed'
+ * using the MurmurHash3 algorithm
+ */
+
+uint32_t
+murmurhash (const char *, uint32_t, uint32_t);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

include/util.h

@@ -0,0 +1,4 @@
+#pragma once
+
+#define UDIV_UP(a, b) (((a) + (b) - 1) / (b))
+#define ALIGN_UP(n, a) (UDIV_UP(n, a) * a)

src/damage-refinery.c

@@ -0,0 +1,111 @@
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <assert.h>
+#include <pixman.h>
+#include <sys/param.h>
+
+#include "damage-refinery.h"
+#include "buffer.h"
+#include "util.h"
+#include "murmurhash.h"
+
+#define HASH_SEED 0xdeadbeef
+
+int damage_refinery_init(struct damage_refinery* self, uint32_t width,
+		uint32_t height)
+{
+	self->width = width;
+	self->height = height;
+
+	uint32_t twidth = UDIV_UP(width, 32);
+	uint32_t theight = UDIV_UP(height, 32);
+
+	self->hashes = calloc(twidth * theight, sizeof(*self->hashes));
+	if (!self->hashes)
+		return -1;
+
+	return 0;
+}
+
+void damage_refinery_destroy(struct damage_refinery* self)
+{
+	free(self->hashes);
+}
+
+static size_t damage_copy_tile(struct damage_refinery* self, void* tile_buffer,
+		uint32_t tx, uint32_t ty, const struct wv_buffer* buffer)
+{
+	// TODO: Support different pixel sizes
+	uint32_t* tile = tile_buffer;
+	uint32_t* pixels = buffer->pixels;
+	int pixel_stride = buffer->stride / 4;
+
+	size_t i = 0;
+	int x_start = tx * 32;
+	int x_stop = MIN(((int)tx + 1) * 32, buffer->width);
+	int y_start = ty * 32;
+	int y_stop = MIN(((int)ty + 1) * 32, buffer->height);
+
+	for (int y = y_start; y < y_stop; ++y)
+		for (int x = x_start; x < x_stop; ++x)
+			tile[i++] = pixels[x + y * pixel_stride];
+
+	return i;
+}
+
+static uint32_t* damage_tile_hash_ptr(struct damage_refinery* self,
+		uint32_t tx, uint32_t ty)
+{
+	uint32_t twidth = UDIV_UP(self->width, 32);
+	return &self->hashes[tx + ty * twidth];
+}
+
+static void damage_tile(struct damage_refinery* self,
+		struct pixman_region16* refined, uint32_t tx, uint32_t ty,
+		int invert_y)
+{
+	uint32_t theight = UDIV_UP(self->height, 32);
+	if (invert_y)
+		pixman_region_union_rect(refined, refined, tx * 32,
+				(theight - ty - 1) * 32, 32, 32);
+	else
+		pixman_region_union_rect(refined, refined,
+				tx * 32, ty * 32, 32, 32);
+}
+
+static void damage_refine_tile(struct damage_refinery* self,
+		struct pixman_region16* refined, uint32_t tx, uint32_t ty,
+		const struct wv_buffer* buffer)
+{
+	uint32_t tile[32 * 32];
+	size_t len = damage_copy_tile(self, tile, tx, ty, buffer);
+	uint32_t hash = murmurhash((void*)tile, len, HASH_SEED);
+	uint32_t* old_hash_ptr = damage_tile_hash_ptr(self, tx, ty);
+	int is_damaged = hash != *old_hash_ptr;
+	*old_hash_ptr = hash;
+
+	if (is_damaged)
+		damage_tile(self, refined, tx, ty, buffer->y_inverted);
+}
+
+void damage_refine(struct damage_refinery* self,
+		struct pixman_region16* refined, 
+		struct pixman_region16* hint,
+		const struct wv_buffer* buffer)
+{
+	// TODO: Use hint
+
+	assert(self->width == (uint32_t)buffer->width &&
+	       self->height == (uint32_t)buffer->height);
+
+	uint32_t twidth = UDIV_UP(self->width, 32);
+	uint32_t theight = UDIV_UP(self->height, 32);
+
+	for (uint32_t ty = 0; ty < theight; ++ty)
+		for (uint32_t tx = 0; tx < twidth; ++tx)
+			damage_refine_tile(self, refined, tx, ty, buffer);
+
+	pixman_region_intersect_rect(refined, refined, 0, 0, self->width,
+			self->height);
+}

src/murmurhash.c

@@ -0,0 +1,91 @@
+/*
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2014 Joseph Werle
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include "murmurhash.h"
+
+uint32_t
+murmurhash (const char *key, uint32_t len, uint32_t seed) {
+  uint32_t c1 = 0xcc9e2d51;
+  uint32_t c2 = 0x1b873593;
+  uint32_t r1 = 15;
+  uint32_t r2 = 13;
+  uint32_t m = 5;
+  uint32_t n = 0xe6546b64;
+  uint32_t h = 0;
+  uint32_t k = 0;
+  uint8_t *d = (uint8_t *) key; // 32 bit extract from `key'
+  const uint32_t *chunks = NULL;
+  const uint8_t *tail = NULL; // tail - last 8 bytes
+  int i = 0;
+  int l = len / 4; // chunk length
+
+  h = seed;
+
+  chunks = (const uint32_t *) (d + l * 4); // body
+  tail = (const uint8_t *) (d + l * 4); // last 8 byte chunk of `key'
+
+  // for each 4 byte chunk of `key'
+  for (i = -l; i != 0; ++i) {
+    // next 4 byte chunk of `key'
+    k = chunks[i];
+
+    // encode next 4 byte chunk of `key'
+    k *= c1;
+    k = (k << r1) | (k >> (32 - r1));
+    k *= c2;
+
+    // append to hash
+    h ^= k;
+    h = (h << r2) | (h >> (32 - r2));
+    h = h * m + n;
+  }
+
+  k = 0;
+
+  // remainder
+  switch (len & 3) { // `len % 4'
+    case 3: k ^= (tail[2] << 16);
+    case 2: k ^= (tail[1] << 8);
+
+    case 1:
+      k ^= tail[0];
+      k *= c1;
+      k = (k << r1) | (k >> (32 - r1));
+      k *= c2;
+      h ^= k;
+  }
+
+  h ^= len;
+
+  h ^= (h >> 16);
+  h *= 0x85ebca6b;
+  h ^= (h >> 13);
+  h *= 0xc2b2ae35;
+  h ^= (h >> 16);
+
+  return h;
+}