From d42d1be8a5592ed2c7827b448c385125f1dd4706 Mon Sep 17 00:00:00 2001
From: Alon Krymgand <me@alon.kr>
Date: Fri, 13 Dec 2024 14:01:47 +0200
Subject: [PATCH] Added `jump` instruction

---
 usm64/isa/jump.go              | 49 ++++++++++++++++++++++++++++++++++
 usm64/managers/instructions.go |  5 ++--
 2 files changed, 52 insertions(+), 2 deletions(-)
 create mode 100644 usm64/isa/jump.go

diff --git a/usm64/isa/jump.go b/usm64/isa/jump.go
new file mode 100644
index 0000000..8352f1c
--- /dev/null
+++ b/usm64/isa/jump.go
@@ -0,0 +1,49 @@
+package usm64isa
+
+import (
+	"alon.kr/x/list"
+	"alon.kr/x/usm/core"
+	"alon.kr/x/usm/gen"
+	usm64core "alon.kr/x/usm/usm64/core"
+)
+
+type JumpInstruction struct {
+	JumpToInstructionIndex uint64
+}
+
+func (i *JumpInstruction) Emulate(
+	ctx *usm64core.EmulationContext,
+) usm64core.EmulationError {
+	ctx.NextInstructionIndex = i.JumpToInstructionIndex
+	return nil
+}
+
+func NewJumpInstruction(
+	targets []usm64core.Register,
+	argument []usm64core.Argument,
+) (usm64core.Instruction, core.ResultList) {
+
+	label, ok := argument[0].(usm64core.Label)
+	if !ok {
+		v := argument[0].Declaration()
+		return nil, list.FromSingle(core.Result{
+			{
+				Type:     core.ErrorResult,
+				Message:  "Expected label argument",
+				Location: &v,
+			},
+		})
+	}
+
+	return &JumpInstruction{
+		JumpToInstructionIndex: label.InstructionIndex,
+	}, core.ResultList{}
+}
+
+func NewJumpInstructionDefinition() gen.InstructionDefinition[usm64core.Instruction] {
+	return &FixedInstructionDefinition{
+		Targets:   0,
+		Arguments: 1,
+		Creator:   NewJumpInstruction,
+	}
+}
diff --git a/usm64/managers/instructions.go b/usm64/managers/instructions.go
index ae93a23..076d63c 100644
--- a/usm64/managers/instructions.go
+++ b/usm64/managers/instructions.go
@@ -30,8 +30,9 @@ func (m *InstructionMap) GetInstructionDefinition(
 func NewInstructionManager() gen.InstructionManager[usm64core.Instruction] {
 	return gen.InstructionManager[usm64core.Instruction](
 		&InstructionMap{
-			"add": usm64isa.NewAddInstructionDefinition(),
-			"put": usm64isa.NewPutInstructionDefinition(),
+			"add":  usm64isa.NewAddInstructionDefinition(),
+			"put":  usm64isa.NewPutInstructionDefinition(),
+			"jump": usm64isa.NewJumpInstructionDefinition(),
 		},
 	)
 }