adding C bindings

README.md

@@ -1,6 +1,6 @@
 # SPIR-V Interpreter <a href="https://git.kbz8.me/kbz_8/SPIRV-Interpreter/actions?workflows=build.yml"><img src="https://git.kbz8.me/kbz_8/SPIRV-Interpreter/actions/workflows/build.yml/badge.svg"></a> <a href="https://git.kbz8.me/kbz_8/SPIRV-Interpreter/actions?workflows=test.yml"><img src="https://git.kbz8.me/kbz_8/SPIRV-Interpreter/actions/workflows/test.yml/badge.svg"></a>
 
-A small footprint SPIR-V interpreter to execute SPIR-V shaders on the CPU. It is designed to be used with multiple runtimes concurrently.
+A small footprint SPIR-V interpreter to execute SPIR-V shaders on the CPU. It is designed to be used with multiple runtimes concurrently and can be SIMD accelerated.
 
 ```zig
 const std = @import("std");
@@ -29,3 +29,58 @@ pub fn main() !void {
     std.log.info("Successfully executed", .{});
 }
 ```
+
+## C bindings
+
+### Build
+To build the FFI bindings just
+```
+zig build ffi-c --release=[fast, small, safe]
+```
+
+You can also build a shared lib using
+```
+zig build ffi-c --release=[fast, small, sage] -Dffi-build-static=false
+```
+
+You'll find the library in `./zig-out/lib/` and the header file in `./zig-out/include/` or in `./ffi/`.
+
+### Example
+
+```c
+#include <stdio.h>
+#include <SpirvInterpreter.h>
+
+static const unsigned char shader_source[]  = {
+    /* Shader bytecode */
+}
+
+int main(void)
+{
+    SpvModule module;
+    SpvModuleOptions options;
+    options.use_simd_vectors_specializations = 1;
+
+    if(SpvInitModule(&module, (SpvWord*)shader_source, sizeof(shader_source) / 4, options) != SPV_RESULT_SUCCESS)
+        return -1;
+
+    SpvRuntime runtime;
+    if(SpvInitRuntime(&runtime, module) != SPV_RESULT_SUCCESS)
+        return -1;
+
+    SpvWord main_entry_index;
+    SpvGetEntryPointByName(runtime, "main", &main_entry_index);
+    SpvCallEntryPoint(runtime, main_entry_index);
+
+    float output[4];
+    SpvWord output_result;
+    SpvGetResultByName(runtime, "color", &output_result);
+    SpvReadOutput(runtime, (SpvByte*)output, sizeof(output), output_result);
+
+    printf("Output: Vec4[%f, %f, %f, %f]\n", output[0], output[1], output[2], output[3]);
+
+    SpvDeinitRuntime(runtime);
+    SpvDeinitModule(module);
+    return 0;
+}
+```