From 50f986fb136a9562c99f68a9855fb6d26d735861 Mon Sep 17 00:00:00 2001
From: Ian Gulliver <git@flamingcow.io>
Date: Fri, 19 Nov 2021 16:30:11 -1000
Subject: [PATCH] Conditional return instructions

---
 asm/opcodes.go      | 18 +++++++++----
 test/opcode_test.go | 66 ++++++++++++++++++++++++++++++++++-----------
 vm/opcode.go        | 13 ++++++---
 vm/ophandler.go     | 27 ++++++++++++++-----
 4 files changed, 94 insertions(+), 30 deletions(-)

diff --git a/asm/opcodes.go b/asm/opcodes.go
index bee6ce7..d0384e4 100644
--- a/asm/opcodes.go
+++ b/asm/opcodes.go
@@ -3,10 +3,8 @@ package asm
 import "github.com/firestuff/subcoding/vm"
 
 var opCodeByName = map[string]vm.OpCodeType{
-	"noop":   vm.OpNoOp,
-	"nop":    vm.OpNop,
-	"return": vm.OpReturn,
-	"ret":    vm.OpRet,
+	"noop": vm.OpNoOp,
+	"nop":  vm.OpNop,
 
 	"move": vm.OpMove,
 	"mov":  vm.OpMov,
@@ -53,6 +51,13 @@ var opCodeByName = map[string]vm.OpCodeType{
 	"calt":        vm.OpCalT,
 	"calliffalse": vm.OpCallIfFalse,
 	"calf":        vm.OpCalF,
+
+	"return":        vm.OpReturn,
+	"ret":           vm.OpRet,
+	"returniftrue":  vm.OpReturnIfTrue,
+	"rett":          vm.OpRetT,
+	"returniffalse": vm.OpReturnIfFalse,
+	"retf":          vm.OpRetF,
 }
 
 type operandType int
@@ -66,7 +71,6 @@ const (
 
 var operandsByOpCode = map[vm.OpCodeType][]operandType{
 	vm.OpNop: []operandType{},
-	vm.OpRet: []operandType{},
 
 	vm.OpMov:  []operandType{r, us},
 	vm.OpAdd:  []operandType{r, us},
@@ -92,4 +96,8 @@ var operandsByOpCode = map[vm.OpCodeType][]operandType{
 	vm.OpCal:  []operandType{s},
 	vm.OpCalT: []operandType{s},
 	vm.OpCalF: []operandType{s},
+
+	vm.OpRet:  []operandType{},
+	vm.OpRetT: []operandType{},
+	vm.OpRetF: []operandType{},
 }
diff --git a/test/opcode_test.go b/test/opcode_test.go
index 8423770..8359890 100644
--- a/test/opcode_test.go
+++ b/test/opcode_test.go
@@ -11,21 +11,6 @@ functions:
 	expectGlobalMemory(t, state, 0, 0)
 }
 
-func TestRet(t *testing.T) {
-	state := assembleAndExecute(t, `
-functions:
-- - [cal, +1]
-  - [add, g0, 1]
-  - [ret]
-
-- - [mov, g0, 5]
-  - [ret]
-  - [add, g0, 2]
-`)
-
-	expectGlobalMemory(t, state, 0, 6)
-}
-
 func TestMov(t *testing.T) {
 	state := assembleAndExecute(t, `
 functions:
@@ -360,3 +345,54 @@ functions:
 
 	expectGlobalMemory(t, state, 0, 16)
 }
+
+func TestRet(t *testing.T) {
+	state := assembleAndExecute(t, `
+functions:
+- - [cal, +1]
+  - [add, g0, 1]
+  - [ret]
+
+- - [mov, g0, 5]
+  - [ret]
+  - [add, g0, 2]
+`)
+
+	expectGlobalMemory(t, state, 0, 6)
+}
+
+func TestRetT(t *testing.T) {
+	state := assembleAndExecute(t, `
+functions:
+- - [cal, +1]
+  - [add, g0, 1]
+
+- - [add, g0, 2]
+  - [eq, 0, 0]
+  - [rett]
+  - [add, g0, 4]
+  - [eq, 0, 1]
+  - [rett]
+  - [add, g0, 8]
+`)
+
+	expectGlobalMemory(t, state, 0, 3)
+}
+
+func TestRetF(t *testing.T) {
+	state := assembleAndExecute(t, `
+functions:
+- - [cal, +1]
+  - [add, g0, 1]
+
+- - [add, g0, 2]
+  - [eq, 0, 0]
+  - [retf]
+  - [add, g0, 4]
+  - [eq, 0, 1]
+  - [retf]
+  - [add, g0, 8]
+`)
+
+	expectGlobalMemory(t, state, 0, 7)
+}
diff --git a/vm/opcode.go b/vm/opcode.go
index 4056df0..956ba33 100644
--- a/vm/opcode.go
+++ b/vm/opcode.go
@@ -3,10 +3,8 @@ package vm
 type OpCodeType uint32
 
 const (
-	OpNoOp   OpCodeType = 0x00000000
-	OpNop               = OpNoOp
-	OpReturn            = 0x00000002
-	OpRet               = OpReturn
+	OpNoOp OpCodeType = 0x00000000
+	OpNop             = OpNoOp
 
 	OpMove = 0x00000100
 	OpMov  = OpMove
@@ -53,4 +51,11 @@ const (
 	OpCalT        = OpCallIfTrue
 	OpCallIfFalse = 0x00000502
 	OpCalF        = OpCallIfFalse
+
+	OpReturn        = 0x00000600
+	OpRet           = OpReturn
+	OpReturnIfTrue  = 0x00000601
+	OpRetT          = OpReturnIfTrue
+	OpReturnIfFalse = 0x00000602
+	OpRetF          = OpReturnIfFalse
 )
diff --git a/vm/ophandler.go b/vm/ophandler.go
index 9f7a426..330ab93 100644
--- a/vm/ophandler.go
+++ b/vm/ophandler.go
@@ -3,8 +3,7 @@ package vm
 type opHandler func(*State, *Instruction)
 
 var opHandlers = map[OpCodeType]opHandler{
-	OpNoOp:   (*State).handleNoOp,
-	OpReturn: (*State).handleReturn,
+	OpNoOp: (*State).handleNoOp,
 
 	OpMove: (*State).handleMove,
 
@@ -31,15 +30,15 @@ var opHandlers = map[OpCodeType]opHandler{
 	OpCall:        (*State).handleCall,
 	OpCallIfTrue:  (*State).handleCallIfTrue,
 	OpCallIfFalse: (*State).handleCallIfFalse,
+
+	OpReturn:        (*State).handleReturn,
+	OpReturnIfTrue:  (*State).handleReturnIfTrue,
+	OpReturnIfFalse: (*State).handleReturnIfFalse,
 }
 
 func (state *State) handleNoOp(instr *Instruction) {
 }
 
-func (state *State) handleReturn(instr *Instruction) {
-	state.ret()
-}
-
 func (state *State) handleMove(instr *Instruction) {
 	in := state.readUnsigned(&instr.Operand2)
 	state.writeUnsigned(&instr.Operand1, in)
@@ -162,3 +161,19 @@ func (state *State) handleCallIfFalse(instr *Instruction) {
 		state.handleCall(instr)
 	}
 }
+
+func (state *State) handleReturn(instr *Instruction) {
+	state.ret()
+}
+
+func (state *State) handleReturnIfTrue(instr *Instruction) {
+	if state.comparisonResult == true {
+		state.handleReturn(instr)
+	}
+}
+
+func (state *State) handleReturnIfFalse(instr *Instruction) {
+	if state.comparisonResult == false {
+		state.handleReturn(instr)
+	}
+}