libmach: initial API bindings for mach core

libmach/.gitignore

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+build/
+test

libmach/Makefile

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+build/libmach.dylib: ../build.zig ../src/*.zig ../src/**/*.zig
+	cd ..; zig build
+
+test: test.c build/libmach.dylib
+	clang -L./build -lmach -o test test.c
+
+test_c: test
+	# my best attempt at cross-platform dynamic linking (for now)
+	DYLD_LIBRARY_PATH=./build LD_LIBRARY_OATH=./build ./test
+
+test_lisp: build/libmach.dylib
+	sbcl --load test.lisp

libmach/README.md

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+# libmach
+
+Build the `libmach` dynamic library by running `make` (or running `zig build` in the parent directory).
+The resulting binary should be located in `libmach/build/`.
+
+Test the functionality of `libmach` using `make test_c` and `make test_lisp`.
+These commands use C and Lisp to call into `libmach`, and both should show a blank window for exactly 1 second.
+
+Note: `make test_lisp` requires a relatively recent version of Steel Bank Common Lisp (`sbcl`) to be installed.
+
+You can find the Zig source code for `libmach` in `src/bindings.zig`.

libmach/test.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+typedef void mach_core_callback(void*);
+
+// `libmach` exported API bindings
+void mach_core_set_init(mach_core_callback);
+void mach_core_set_update(mach_core_callback);
+void mach_core_set_deinit(mach_core_callback);
+void mach_run(void);
+void core_set_should_close(void*);
+float core_delta_time(void*);
+
+static float elapsed = 0;
+
+void my_init(void* core) {
+  printf("My init!\n");
+}
+
+void my_update(void* core) {
+  float dt = core_delta_time(core);
+  if (elapsed < 1.0) {
+    elapsed += dt;
+  } else {
+    core_set_should_close(core);
+  }
+  printf("My update! total time = %f\n", elapsed);
+}
+
+void my_deinit(void* core) {
+  printf("My deinit!\n");
+}
+
+int main() {
+  mach_core_set_init(my_init);
+  mach_core_set_update(my_update);
+  mach_core_set_deinit(my_deinit);
+  mach_run();
+  return 0;
+}

libmach/test.lisp

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+;; Tests the behavior of `libmach` using Common Lisp's CFFI
+;; This Lisp script is basically a one-to-one translation of `test.c`
+
+(ql:quickload :cffi)
+
+(defpackage :cffi-user
+  (:use :cl :cffi))
+
+(in-package :cffi-user)
+
+(define-foreign-library libmach
+  (t (:default "./build/libmach")))
+   
+(use-foreign-library libmach)
+
+;; Note: CFFI automatically translates C_style names into lispier kebab-case ones
+
+;; typedef void mach_core_callback(void*);
+(defctype mach-core-callback :pointer)
+
+;; void mach_core_set_init(mach_core_callback);
+(defcfun "mach_core_set_init" :void
+  (callback mach-core-callback))
+
+;; void mach_core_set_update(mach_core_callback);
+(defcfun "mach_core_set_update" :void
+  (callback mach-core-callback))
+
+;; void mach_core_set_deinit(mach_core_callback);
+(defcfun "mach_core_set_deinit" :void
+  (callback mach-core-callback))
+
+;; void mach_run(void);
+(defcfun "mach_run" :void)
+
+;; void core_set_should_close(void*);
+(defcfun "core_set_should_close" :void (core :pointer))
+
+;; float core_delta_time(void*);
+(defcfun "core_delta_time" :float (core :pointer))
+
+(defcallback my-init :void ((core :pointer))
+  (format t "Hello from my-init!~%"))
+
+(defvar *elapsed* 0.0)
+
+(defcallback my-update :void ((core :pointer))
+  (format t "Hello from my-update ~a~%" *elapsed*)
+  (if (< *elapsed* 1.0)
+      (incf *elapsed* (core-delta-time core))
+      (core-set-should-close core)))
+
+(defcallback my-deinit :void ((core :pointer))
+  (format t "Hello from my-deinit!~%"))
+
+(mach-core-set-init (callback my-init))
+
+(mach-core-set-update (callback my-update))
+
+(mach-core-set-deinit (callback my-deinit))
+
+(mach-run)
+
+(sb-ext:exit)