built on arm64

countlines_arm64.go

@@ -0,0 +1,14 @@
+//go:build arm64 && !gccgo && !appengine
+
+package countlines
+
+func CountNewlines(s []byte) uint64 {
+	if len(s) == 0 {
+		return 0
+	}
+
+	return countNewlinesASM(&s[0], uint64(len(s)))
+}
+
+//go:noescape
+func countNewlinesASM(src *byte, len uint64) (ret uint64)

countlines_arm64.s

@@ -3,11 +3,11 @@
 #include "textflag.h"
 
 TEXT ·countNewlinesASM(SB),NOSPLIT,$0
-	MOVQ src+0(FP), R1
-	MOVQ len+8(FP), R2
+	MOVD src+0(FP), R1
+	MOVD len+8(FP), R2
 
 	MOVD ZR, R0
-  VMOVI $0x0A V23.B16
+	VMOVI $0x0A, V23.B16
 
 	CMP $16, R2
 	BLT tail
@@ -65,7 +65,8 @@ tail:
 next:
 
 	SUB $1, R2
-	JNZ tail
+	CMP ZR, R2
+	BNE tail
 
 
 ret:

countlines_generic.go

@@ -1,4 +1,4 @@
-//go:build !amd64 || gccgo || appengine
+//go:build (!amd64 && !arm64) || gccgo || appengine
 
 package countlines