1 files changed, 340 insertions, 0 deletions
diff --git a/src/zstd/contrib/single_file_libs/examples/emscripten.c b/src/zstd/contrib/single_file_libs/examples/emscripten.c
new file mode 100644
index 000000000..10dae8689
--- /dev/null
+++ b/src/zstd/contrib/single_file_libs/examples/emscripten.c
@@ -0,0 +1,340 @@
+/**
+ * \file emscripten.c
+ * Emscripten example of using the single-file \c zstddeclib. Draws a rotating
+ * textured quad with data from the in-line Zstd compressed DXT1 texture (DXT1
+ * being hardware compression, further compressed with Zstd).
+ * \n
+ * Compile using:
+ * \code
+ *	export CC_FLAGS="-Wall -Wextra -Werror -Os -g0 -flto --llvm-lto 3 -lGL -DNDEBUG=1"
+ *	export EM_FLAGS="-s WASM=1 -s ENVIRONMENT=web --shell-file shell.html --closure 1"
+ *	emcc $CC_FLAGS $EM_FLAGS -o out.html emscripten.c
+ * \endcode
+ * 
+ * \author Carl Woffenden, Numfum GmbH (released under a CC0 license)
+ */
+
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <emscripten/emscripten.h>
+#include <emscripten/html5.h>
+
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+
+#include "../zstddeclib.c"
+
+//************************* Test Data (DXT texture) **************************/
+
+/**
+ * Zstd compressed DXT1 256x256 texture source.
+ * \n
+ * See \c testcard.png for the original.
+ */
+static uint8_t const srcZstd[] = {
+#include "testcard-zstd.inl"
+};
+
+/**
+ * Uncompressed size of \c #srcZstd.
+ */
+#define DXT1_256x256 32768
+
+/**
+ * Destination for decoding \c #srcZstd.
+ */
+static uint8_t dstDxt1[DXT1_256x256] = {};
+
+#ifndef ZSTD_VERSION_MAJOR
+/**
+ * For the case where the decompression library hasn't been included we add a
+ * dummy function to fake the process and stop the buffers being optimised out.
+ */
+size_t ZSTD_decompress(void* dst, size_t dstLen, const void* src, size_t srcLen) {
+	return (memcmp(dst, src, (srcLen < dstLen) ? srcLen : dstLen)) ? dstLen : 0;
+}
+#endif
+
+//*************************** Program and Shaders ***************************/
+
+/**
+ * Program object ID.
+ */
+static GLuint progId = 0;
+
+/**
+ * Vertex shader ID.
+ */
+static GLuint vertId = 0;
+
+/**
+ * Fragment shader ID.
+ */
+static GLuint fragId = 0;
+
+//********************************* Uniforms *********************************/
+
+/**
+ * Quad rotation angle ID.
+ */
+static GLint uRotId = -1;
+
+/**
+ * Draw colour ID.
+ */
+static GLint uTx0Id = -1;
+
+//******************************* Shader Source ******************************/
+
+/**
+ * Vertex shader to draw texture mapped polys with an applied rotation.
+ */
+static GLchar const vertShader2D[] =
+#if GL_ES_VERSION_2_0
+	"#version 100\n"
+	"precision mediump float;\n"
+#else
+	"#version 120\n"
+#endif
+	"uniform   float uRot;"	// rotation
+	"attribute vec2  aPos;"	// vertex position coords
+	"attribute vec2  aUV0;"	// vertex texture UV0
+	"varying   vec2  vUV0;"	// (passed to fragment shader)
+	"void main() {"
+	"	float cosA = cos(radians(uRot));"
+	"	float sinA = sin(radians(uRot));"
+	"	mat3 rot = mat3(cosA, -sinA, 0.0,"
+	"					sinA,  cosA, 0.0,"
+	"					0.0,   0.0,  1.0);"
+	"	gl_Position = vec4(rot * vec3(aPos, 1.0), 1.0);"
+	"	vUV0 = aUV0;"
+	"}";
+
+/**
+ * Fragment shader for the above polys.
+ */
+static GLchar const fragShader2D[] =
+#if GL_ES_VERSION_2_0
+	"#version 100\n"
+	"precision mediump float;\n"
+#else
+	"#version 120\n"
+#endif
+	"uniform sampler2D uTx0;"
+	"varying vec2      vUV0;" // (passed from fragment shader)
+	"void main() {"
+	"	gl_FragColor = texture2D(uTx0, vUV0);"
+	"}";
+
+/**
+ * Helper to compile a shader.
+ * 
+ * \param type shader type
+ * \param text shader source
+ * \return the shader ID (or zero if compilation failed)
+ */
+static GLuint compileShader(GLenum const type, const GLchar* text) {
+	GLuint shader = glCreateShader(type);
+	if (shader) {
+		glShaderSource (shader, 1, &text, NULL);
+		glCompileShader(shader);
+		GLint compiled;
+		glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
+		if (compiled) {
+			return shader;
+		} else {
+			GLint logLen;
+			glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &logLen);
+			if (logLen > 1) {
+				GLchar*  logStr = malloc(logLen);
+				glGetShaderInfoLog(shader, logLen, NULL, logStr);
+			#ifndef NDEBUG
+				printf("Shader compilation error: %s\n", logStr);
+			#endif
+				free(logStr);
+			}
+			glDeleteShader(shader);
+		}
+	}
+	return 0;
+}
+
+//********************************** Helpers *********************************/
+
+/**
+ * Vertex position index.
+ */
+#define GL_VERT_POSXY_ID 0
+
+/**
+ * Vertex UV0 index.
+ */
+#define GL_VERT_TXUV0_ID 1
+
+ /**
+  * \c GL vec2 storage type.
+  */
+struct vec2 {
+	float x;
+	float y;
+};
+
+/**
+ * Combined 2D vertex and 2D texture coordinates.
+ */
+struct posTex2d {
+	struct vec2 pos;
+	struct vec2 uv0;
+};
+
+//****************************************************************************/
+
+/**
+ * Current quad rotation angle (in degrees, updated per frame).
+ */
+static float rotDeg = 0.0f;
+
+/**
+ * Emscripten (single) GL context.
+ */
+static EMSCRIPTEN_WEBGL_CONTEXT_HANDLE glCtx = 0;
+
+/**
+ * Emscripten resize handler.
+ */
+static EM_BOOL resize(int type, const EmscriptenUiEvent* e, void* data) {
+	double surfaceW;
+	double surfaceH;
+	if (emscripten_get_element_css_size   ("#canvas", &surfaceW, &surfaceH) == EMSCRIPTEN_RESULT_SUCCESS) {
+		emscripten_set_canvas_element_size("#canvas",  surfaceW,  surfaceH);
+		if (glCtx) {
+			glViewport(0, 0, (int) surfaceW, (int) surfaceH);
+		}
+	}
+	(void) type;
+	(void) data;
+	(void) e;
+	return EM_FALSE;
+}
+
+/**
+ * Boilerplate to create a WebGL context.
+ */
+static EM_BOOL initContext() {
+	// Default attributes
+	EmscriptenWebGLContextAttributes attr;
+	emscripten_webgl_init_context_attributes(&attr);
+	if ((glCtx = emscripten_webgl_create_context("#canvas", &attr))) {
+		// Bind the context and fire a resize to get the initial size
+		emscripten_webgl_make_context_current(glCtx);
+		emscripten_set_resize_callback(EMSCRIPTEN_EVENT_TARGET_DOCUMENT, NULL, EM_FALSE, resize);
+		resize(0, NULL, NULL);
+		return EM_TRUE;
+	}
+	return EM_FALSE;
+}
+
+/**
+ * Called once per frame (clears the screen and draws the rotating quad).
+ */
+static void tick() {
+	glClearColor(1.0f, 0.0f, 1.0f, 1.0f);
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+	if (uRotId >= 0) {
+		glUniform1f(uRotId, rotDeg);
+		rotDeg += 0.1f;
+		if (rotDeg >= 360.0f) {
+			rotDeg -= 360.0f;
+		}
+	}
+
+	glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, 0);
+	glFlush();
+}
+
+/**
+ * Creates the GL context, shaders and quad data, decompresses the Zstd data
+ * and 'uploads' the resulting texture.
+ * 
+ * As a (naive) comparison, removing Zstd and building with "-Os -g0 s WASM=1
+ * -lGL emscripten.c" results in a 15kB WebAssembly file; re-adding Zstd
+ * increases the Wasm by 26kB.
+ */
+int main() {
+	if (initContext()) {
+		// Compile shaders and set the initial GL state
+		if ((progId = glCreateProgram())) {
+			 vertId = compileShader(GL_VERTEX_SHADER,   vertShader2D);
+			 fragId = compileShader(GL_FRAGMENT_SHADER, fragShader2D);
+			 
+			 glBindAttribLocation(progId, GL_VERT_POSXY_ID, "aPos");
+			 glBindAttribLocation(progId, GL_VERT_TXUV0_ID, "aUV0");
+			 
+			 glAttachShader(progId, vertId);
+			 glAttachShader(progId, fragId);
+			 glLinkProgram (progId);
+			 glUseProgram  (progId);
+			 uRotId = glGetUniformLocation(progId, "uRot");
+			 uTx0Id = glGetUniformLocation(progId, "uTx0");
+			 if (uTx0Id >= 0) {
+				 glUniform1i(uTx0Id, 0);
+			 }
+			
+			 glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+			 glEnable(GL_BLEND);
+			 glDisable(GL_DITHER);
+
+			 glCullFace(GL_BACK);
+			 glEnable(GL_CULL_FACE);
+		}
+		
+		GLuint vertsBuf = 0;
+		GLuint indexBuf = 0;
+		GLuint txName   = 0;
+		// Create the textured quad (vert positions then UVs)
+		struct posTex2d verts2d[] = {
+			{{-0.85f, -0.85f}, {0.0f, 0.0f}}, // BL
+			{{ 0.85f, -0.85f}, {1.0f, 0.0f}}, // BR
+			{{-0.85f,  0.85f}, {0.0f, 1.0f}}, // TL
+			{{ 0.85f,  0.85f}, {1.0f, 1.0f}}, // TR
+		};
+		uint16_t index2d[] = {
+			0, 1, 2,
+			2, 1, 3,
+		};
+		glGenBuffers(1, &vertsBuf);
+		glBindBuffer(GL_ARRAY_BUFFER, vertsBuf);
+		glBufferData(GL_ARRAY_BUFFER,
+			sizeof(verts2d), verts2d, GL_STATIC_DRAW);
+		glVertexAttribPointer(GL_VERT_POSXY_ID, 2,
+			GL_FLOAT, GL_FALSE, sizeof(struct posTex2d), 0);
+		glVertexAttribPointer(GL_VERT_TXUV0_ID, 2,
+			GL_FLOAT, GL_FALSE, sizeof(struct posTex2d),
+				(void*) offsetof(struct posTex2d, uv0));
+		glGenBuffers(1, &indexBuf);
+		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuf);
+		glBufferData(GL_ELEMENT_ARRAY_BUFFER,
+			sizeof(index2d), index2d, GL_STATIC_DRAW);
+		glEnableVertexAttribArray(GL_VERT_POSXY_ID);
+		glEnableVertexAttribArray(GL_VERT_TXUV0_ID);
+		
+		// Decode the Zstd data and create the texture
+		if (ZSTD_decompress(dstDxt1, DXT1_256x256, srcZstd, sizeof srcZstd) == DXT1_256x256) {
+			glGenTextures(1, &txName);
+			glBindTexture(GL_TEXTURE_2D, txName);
+			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+			glCompressedTexImage2D(GL_TEXTURE_2D, 0,
+				GL_COMPRESSED_RGB_S3TC_DXT1_EXT,
+					256, 256, 0, DXT1_256x256, dstDxt1);
+		} else {
+			printf("Failed to decode Zstd data\n");
+		}
+		emscripten_set_main_loop(tick, 0, EM_FALSE);
+		emscripten_exit_with_live_runtime();
+	}
+	return EXIT_FAILURE;
+}