From 73b5951391a9c206414b2f460a043374b1383b94 Mon Sep 17 00:00:00 2001
From: Richard Musiol <mail@richard-musiol.de>
Date: Tue, 15 May 2018 00:52:18 +0200
Subject: [PATCH] misc/wasm: fix passing large negative integers from JS to Go
This commit addresses a FIXME left in the code of wasm_exec.js to
properly get the upper 32 bit of a JS number to be stored as an
64-bit integer. A bitshift operation is not possible, because in
JavaScript bitshift operations only operate on the lower 32 bits.
Change-Id: I8f627fd604e592682d9d322942a4852db64a7f66
Reviewed-on: https://go-review.googlesource.com/113076
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
---
misc/wasm/wasm_exec.js | 6 +-----
src/syscall/js/js_test.go | 18 ++++++++++++++++++
2 files changed, 19 insertions(+), 5 deletions(-)
diff --git a/misc/wasm/wasm_exec.js b/misc/wasm/wasm_exec.js
index f616b5a1a6f..d61bbcc95a4 100755
--- a/misc/wasm/wasm_exec.js
+++ b/misc/wasm/wasm_exec.js
@@ -77,11 +77,7 @@
const setInt64 = (addr, v) => {
mem().setUint32(addr + 0, v, true);
- if (v >= 0) {
- mem().setUint32(addr + 4, v / 4294967296, true);
- } else {
- mem().setUint32(addr + 4, -1, true); // FIXME
- }
+ mem().setUint32(addr + 4, Math.floor(v / 4294967296), true);
}
const getInt64 = (addr) => {
diff --git a/src/syscall/js/js_test.go b/src/syscall/js/js_test.go
index 39e3744a995..ca065e321d3 100644
--- a/src/syscall/js/js_test.go
+++ b/src/syscall/js/js_test.go
@@ -58,6 +58,24 @@ func TestInt(t *testing.T) {
}
}
+func TestIntConversion(t *testing.T) {
+ testIntConversion(t, 0)
+ testIntConversion(t, 1)
+ testIntConversion(t, -1)
+ testIntConversion(t, 1<<20)
+ testIntConversion(t, -1<<20)
+ testIntConversion(t, 1<<40)
+ testIntConversion(t, -1<<40)
+ testIntConversion(t, 1<<60)
+ testIntConversion(t, -1<<60)
+}
+
+func testIntConversion(t *testing.T, want int) {
+ if got := js.ValueOf(want).Int(); got != want {
+ t.Errorf("got %#v, want %#v", got, want)
+ }
+}
+
func TestFloat(t *testing.T) {
want := 42.123
o := dummys.Get("someFloat")
--
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