From 0b54870bfe4c50bd04f987483c7c74fd0aa2e241 Mon Sep 17 00:00:00 2001
From: Evgeniy Stratonikov <evgeniy@nspcc.ru>
Date: Tue, 2 Mar 2021 14:56:32 +0300
Subject: [PATCH] compiler: add missing math routines

Add interops for ABS, SIGN, MIN, MAX, WITHIN opcodes
---
 pkg/compiler/syscall_test.go        | 60 +++++++++++++++++++++++++++++
 pkg/interop/math/math.go            | 29 ++++++++++++++
 pkg/interop/neogointernal/opcode.go |  5 +++
 3 files changed, 94 insertions(+)

diff --git a/pkg/compiler/syscall_test.go b/pkg/compiler/syscall_test.go
index 5ce03d9e2..9630c1f8c 100644
--- a/pkg/compiler/syscall_test.go
+++ b/pkg/compiler/syscall_test.go
@@ -133,4 +133,64 @@ func TestOpcode(t *testing.T) {
 		}`
 		eval(t, src, big.NewInt(3))
 	})
+	t.Run("SIGN", func(t *testing.T) {
+		src := `package foo
+		import "github.com/nspcc-dev/neo-go/pkg/interop/math"
+		func Main() []int {
+			signs := make([]int, 3)
+			signs[0] = math.Sign(-123)
+			signs[1] = math.Sign(0)
+			signs[2] = math.Sign(42)
+			return signs
+		}`
+		eval(t, src, []stackitem.Item{
+			stackitem.Make(-1),
+			stackitem.Make(0),
+			stackitem.Make(1),
+		})
+	})
+	t.Run("ABS", func(t *testing.T) {
+		src := `package foo
+		import "github.com/nspcc-dev/neo-go/pkg/interop/math"
+		func Main() int {
+			return math.Abs(-3)
+		}`
+		eval(t, src, big.NewInt(3))
+	})
+	t.Run("MAX", func(t *testing.T) {
+		src := `package foo
+		import "github.com/nspcc-dev/neo-go/pkg/interop/math"
+		func Main() int {
+			return math.Max(1, 2) + math.Max(8, 3)
+		}`
+		eval(t, src, big.NewInt(10))
+	})
+	t.Run("MIN", func(t *testing.T) {
+		src := `package foo
+		import "github.com/nspcc-dev/neo-go/pkg/interop/math"
+		func Main() int {
+			return math.Min(1, 2) + math.Min(8, 3)
+		}`
+		eval(t, src, big.NewInt(4))
+	})
+	t.Run("WITHIN", func(t *testing.T) {
+		src := `package foo
+		import "github.com/nspcc-dev/neo-go/pkg/interop/math"
+		func Main() []bool {
+			r := make([]bool, 5)
+			r[0] = math.Within(2, 3, 5)
+			r[1] = math.Within(3, 3, 5)
+			r[2] = math.Within(4, 3, 5)
+			r[3] = math.Within(5, 3, 5)
+			r[4] = math.Within(6, 3, 5)
+			return r
+		}`
+		eval(t, src, []stackitem.Item{
+			stackitem.Make(false),
+			stackitem.Make(true),
+			stackitem.Make(true),
+			stackitem.Make(false),
+			stackitem.Make(false),
+		})
+	})
 }
diff --git a/pkg/interop/math/math.go b/pkg/interop/math/math.go
index 86cbd020d..6097bae1c 100644
--- a/pkg/interop/math/math.go
+++ b/pkg/interop/math/math.go
@@ -12,3 +12,32 @@ func Pow(a, b int) int {
 func Sqrt(x int) int {
 	return neogointernal.Opcode1("SQRT", x).(int)
 }
+
+// Sign returns:
+//
+//	-1 if x <  0
+//	 0 if x == 0
+//	+1 if x >  0
+func Sign(a int) int {
+	return neogointernal.Opcode1("SIGN", a).(int)
+}
+
+// Abs returns absolute value of a.
+func Abs(a int) int {
+	return neogointernal.Opcode1("ABS", a).(int)
+}
+
+// Max returns maximum of a, b.
+func Max(a, b int) int {
+	return neogointernal.Opcode2("MAX", a, b).(int)
+}
+
+// Min returns minimum of a, b.
+func Min(a, b int) int {
+	return neogointernal.Opcode2("MIN", a, b).(int)
+}
+
+// Within returns true if a <= x < b.
+func Within(x, a, b int) bool {
+	return neogointernal.Opcode3("WITHIN", x, a, b).(bool)
+}
diff --git a/pkg/interop/neogointernal/opcode.go b/pkg/interop/neogointernal/opcode.go
index 3a7cb00a4..2e18b936b 100644
--- a/pkg/interop/neogointernal/opcode.go
+++ b/pkg/interop/neogointernal/opcode.go
@@ -9,3 +9,8 @@ func Opcode1(op string, arg interface{}) interface{} {
 func Opcode2(op string, arg1, arg2 interface{}) interface{} {
 	return nil
 }
+
+// Opcode3 emits opcode with 3 arguments.
+func Opcode3(op string, arg1, arg2, arg3 interface{}) interface{} {
+	return nil
+}