From 937ccf60c9c9f05b10cbfb244364cbe94ec9271c Mon Sep 17 00:00:00 2001
From: BjoernSchilberg <bjoern.schilberg@posteo.de>
Date: Sun, 12 Feb 2023 22:24:16 +0100
Subject: [PATCH] Added a tinygo example.

---
 examples/tinygo/build.sh    |  6 ++++++
 examples/tinygo/main.go     | 38 +++++++++++++++++++++++++++++++++++++
 examples/tinygo/target.json | 23 ++++++++++++++++++++++
 3 files changed, 67 insertions(+)
 create mode 100755 examples/tinygo/build.sh
 create mode 100644 examples/tinygo/main.go
 create mode 100644 examples/tinygo/target.json

diff --git a/examples/tinygo/build.sh b/examples/tinygo/build.sh
new file mode 100755
index 0000000..174e179
--- /dev/null
+++ b/examples/tinygo/build.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+
+tinygo build -o cart.wasm -target target.json ./main.go
+uw8 filter-exports cart.wasm cart.wasm && \
+#wasm-opt -Oz --fast-math --strip-producers -o cart.wasm cart.wasm && \
+uw8 pack -l 9 cart.wasm cart.uw8
diff --git a/examples/tinygo/main.go b/examples/tinygo/main.go
new file mode 100644
index 0000000..f0f2c25
--- /dev/null
+++ b/examples/tinygo/main.go
@@ -0,0 +1,38 @@
+package main
+
+import (
+	"math"
+	"unsafe"
+)
+
+//go:wasm-module env
+//export atan2
+func atan2(x, y float32) float32
+
+//go:wasm-module env
+//export time
+func time() float32
+
+func sqrt(v float32) float32 {
+	return float32(math.Sqrt(float64(v)))
+}
+
+var FRAMEBUFFER = (*[320 * 240]byte)(unsafe.Pointer(uintptr(120)))
+
+//export upd
+func upd() {
+	var i int
+	for i < 320*240 {
+		t := time() * 63.0
+		x := float32(i%320 - 160)
+		y := float32(i/320 - 120)
+		d := float32(40000.0) / sqrt(x*x+y*y)
+		u := atan2(x, y) * 512.0 / 3.141
+		c := uint8((int(d+t*2.0) ^ int(u+t)) >> 4)
+		FRAMEBUFFER[i] = c
+		i++
+	}
+}
+
+func main() {
+}
diff --git a/examples/tinygo/target.json b/examples/tinygo/target.json
new file mode 100644
index 0000000..e26bb37
--- /dev/null
+++ b/examples/tinygo/target.json
@@ -0,0 +1,23 @@
+{
+  "llvm-target": "wasm32--wasi",
+  "build-tags": [ "tinygo.wasm" ],
+  "goos": "js",
+  "goarch": "wasm",
+  "linker": "wasm-ld",
+  "libc": "wasi-libc",
+  "cflags": [
+    "--target=wasm32--wasi",
+    "--sysroot={root}/lib/wasi-libc/sysroot",
+    "-Oz"
+  ],
+  "ldflags": [
+    "--no-entry",
+    "--export-all",
+    "--import-memory",
+    "--initial-memory=262144",
+    "--global-base=81920",
+    "-zstack-size=4096",
+    "--strip-all"
+  ],
+  "wasm-abi": "js"
+}