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printf for WASM. Requires std_sprintf <https://github.com/nothings/stb>
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| #ifndef JS_PRINTF_H | |
| #define JS_PRINTF_H | |
| // This is free and unencumbered software released into the public domain. | |
| // Anyone is free to copy, modify, publish, use, compile, sell, or distribute this | |
| // software, either in source code form or as a compiled binary, for any purpose, | |
| // commercial or non-commercial, and by any means. | |
| // In jurisdictions that recognize copyright laws, the author or authors of this | |
| // software dedicate any and all copyright interest in the software to the public | |
| // domain. We make this dedication for the benefit of the public at large and to | |
| // the detriment of our heirs and successors. We intend this dedication to be an | |
| // overt act of relinquishment in perpetuity of all present and future rights to | |
| // this software under copyright law. | |
| // 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 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. | |
| // Example usage: | |
| // file: hello.c | |
| // #define export __attribute__((visibility("default"))) | |
| // | |
| // #define JS_PRINTF_IMPLEMENTATION | |
| // #include "js_printf.h" | |
| // | |
| // export void hello(int a, int b) { | |
| // js_printf("Hello, %s!\n", "world"); | |
| // js_printf("%d + %d = %d\n", a, b, a + b); | |
| // } | |
| // file: hello.js | |
| // let memory_buffer | |
| // const decoder = new TextDecoder() | |
| // | |
| // let buf = "" | |
| // | |
| // const wasm = await WebAssembly.instantiateStreaming(fetch("./hello.wasm"), { | |
| // env: { | |
| // js_append_buf(ptr, len) { | |
| // const bytes = new Uint8Array(memory_buffer, ptr, len) | |
| // buf += decoder.decode(bytes) | |
| // }, | |
| // js_flush_buf() { | |
| // console.log(buf) | |
| // buf = "" | |
| // } | |
| // } | |
| // }) | |
| // | |
| // const { exports } = wasm.instance | |
| // | |
| // memory_buffer = exports.memory.buffer | |
| // | |
| // exports.hello(34, 35) | |
| // Compile with: clang -o hello.wasm hello.c -O3 -Wall -Wextra -Wpedantic | |
| // -std=c99 -O3 --target=wasm32 -flto -nostdlib -fvisibility=hidden | |
| // -mbulk-memory -msimd128 -Wl,--no-entry -Wl,--strip-debug -Wl,--lto-O3 | |
| // -Wl,--allow-undefined -Wl,--export-dynamic | |
| extern void js_printf(const char* fmt, ...); | |
| #endif | |
| #ifdef JS_PRINTF_IMPLEMENTATION | |
| #define STB_SPRINTF_IMPLEMENTATION | |
| #include "stb_sprintf.h" | |
| extern void js_append_buf(const char*, int); | |
| extern void js_flush_buf(void); | |
| char* js_printf_cb(const char* buf, void* user, int len) { | |
| stbsp__context *c = (stbsp__context *)user; | |
| js_append_buf(buf, len); | |
| return c->tmp; | |
| } | |
| void js_printf(const char* fmt, ...) { | |
| stbsp__context c; | |
| va_list va; | |
| va_start(va, fmt); | |
| stbsp_vsprintfcb(js_printf_cb, &c, c.tmp, fmt, va); | |
| va_end(va); | |
| js_flush_buf(); | |
| } | |
| #endif |
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