wasi 目标下支持打印 unicode rune

waroot/src/runtime/print_wasi.wat.ws

@@ -38,26 +38,3 @@
 
 	;; {{$$runtime.waPuts/body/end}}
 )
-
-;; 打印字符
-(func $$runtime.waPrintRune (param $ch i32)
-	;; {{$$runtime.waPrintRune/body/begin}}
-
-	(local $sp i32)
-	(local $p_ch i32)
-
-	;; 保存栈指针状态
-	(local.set $sp (global.get $__stack_ptr))
-
-	;; 分配字符
-	(local.set $p_ch (call $$waStackAlloc (i32.const 4)))
-	(i32.store offset=0 align=1 (local.get $p_ch) (local.get $ch))
-
-	;; 输出字符
-	(call $$runtime.waPuts (local.get $p_ch) (i32.const 1))
-
-	;; 重置栈指针
-	(global.set $__stack_ptr (local.get $sp))
-
-	;; {{$$runtime.waPrintRune/body/begin}}
-)

waroot/src/runtime/runtime_wasi.wa

@@ -114,8 +114,62 @@ func waPrintString(s: string) {
 	printString(s)
 }
 
+const (
+	MaxRune   = '\U0010FFFF'
+	RuneError = '\uFFFD'
+	surrogateMin = 0xD800
+	surrogateMax = 0xDFFF
+	tx = 0b10000000
+	t2 = 0b11000000
+	t3 = 0b11100000
+	t4 = 0b11110000
+	maskx = 0b00111111
+
+	rune1Max = 1<<7 - 1
+	rune2Max = 1<<11 - 1
+	rune3Max = 1<<16 - 1
+)
 #wa:linkname $runtime.waPrintRune
-func waPrintRune(ch: i32)
+func waPrintRune(r: i32) {
+	p := make([]byte, 0, 4)
+	n : int
+
+	switch i := uint32(r); {
+	case i <= rune1Max:
+		p[0] = byte(r)
+		n = 1
+	case i <= rune2Max:
+		_ = p[1] // eliminate bounds checks
+		p[0] = t2 | byte(r>>6)
+		p[1] = tx | byte(r)&maskx
+		n = 2
+	case i > MaxRune, surrogateMin <= i && i <= surrogateMax:
+		r = RuneError
+		// fallthrough
+		{
+			_ = p[2] // eliminate bounds checks
+			p[0] = t3 | byte(r>>12)
+			p[1] = tx | byte(r>>6)&maskx
+			p[2] = tx | byte(r)&maskx
+			n = 3
+		}
+	case i <= rune3Max:
+		_ = p[2] // eliminate bounds checks
+		p[0] = t3 | byte(r>>12)
+		p[1] = tx | byte(r>>6)&maskx
+		p[2] = tx | byte(r)&maskx
+		n = 3
+	default:
+		_ = p[3] // eliminate bounds checks
+		p[0] = t4 | byte(r>>18)
+		p[1] = tx | byte(r>>12)&maskx
+		p[2] = tx | byte(r>>6)&maskx
+		p[3] = tx | byte(r)&maskx
+		n = 4
+	}
+
+	printString(string(p[:n]))
+}
 
 #wa:linkname $runtime.waPuts
 func waPuts(ptr: i32, len: i32)