From df725a2b238a70b585884268a82d2c7ee93583e7 Mon Sep 17 00:00:00 2001
From: Eduard Urbach <eduard@urbach.dev>
Date: Wed, 16 Apr 2025 17:38:48 +0200
Subject: [PATCH] Refactored arm package

---
 src/arm/Add_test.go         |  4 ++--
 src/arm/And_test.go         |  4 ++--
 src/arm/Call.go             |  4 ++--
 src/arm/Call_test.go        | 25 +++++++++++++++++++++++++
 src/arm/Compare_test.go     |  4 ++--
 src/arm/Div_test.go         |  2 +-
 src/arm/Jump.go             | 20 +++++++++-----------
 src/arm/Jump_test.go        |  2 +-
 src/arm/LoadAddress_test.go |  2 +-
 src/arm/LoadPair_test.go    |  2 +-
 src/arm/Load_test.go        |  2 +-
 src/arm/Move_test.go        |  8 ++++----
 src/arm/Mul_test.go         |  4 ++--
 src/arm/Negate_test.go      |  2 +-
 src/arm/Or_test.go          |  4 ++--
 src/arm/Shift_test.go       |  4 ++--
 src/arm/StorePair_test.go   |  2 +-
 src/arm/Store_test.go       |  2 +-
 src/arm/Sub_test.go         |  4 ++--
 src/arm/Xor_test.go         |  4 ++--
 src/arm/arm_test.go         |  3 +--
 src/arm/bitmask.go          |  2 +-
 src/arm/condition.go        | 22 ++++++++++++++++++++++
 src/arm/encode.go           |  8 --------
 src/arm/mask.go             | 11 +++++++++++
 src/asmc/armCompiler.go     |  4 +++-
 26 files changed, 102 insertions(+), 53 deletions(-)
 create mode 100644 src/arm/Call_test.go
 create mode 100644 src/arm/condition.go
 create mode 100644 src/arm/mask.go

diff --git a/src/arm/Add_test.go b/src/arm/Add_test.go
index d00d9f6..723580e 100644
--- a/src/arm/Add_test.go
+++ b/src/arm/Add_test.go
@@ -23,7 +23,7 @@ func TestAddRegisterNumber(t *testing.T) {
 		t.Logf("add %s, %s, %d", pattern.Destination, pattern.Source, pattern.Number)
 		code, encodable := arm.AddRegisterNumber(pattern.Destination, pattern.Source, pattern.Number)
 		assert.True(t, encodable)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
 
@@ -40,6 +40,6 @@ func TestAddRegisterRegister(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("add %s, %s, %s", pattern.Destination, pattern.Source, pattern.Operand)
 		code := arm.AddRegisterRegister(pattern.Destination, pattern.Source, pattern.Operand)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/And_test.go b/src/arm/And_test.go
index c8e6317..f5bb123 100644
--- a/src/arm/And_test.go
+++ b/src/arm/And_test.go
@@ -27,7 +27,7 @@ func TestAndRegisterNumber(t *testing.T) {
 		t.Logf("and %s, %s, %d", pattern.Destination, pattern.Source, pattern.Number)
 		code, encodable := arm.AndRegisterNumber(pattern.Destination, pattern.Source, pattern.Number)
 		assert.True(t, encodable)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
 
@@ -44,6 +44,6 @@ func TestAndRegisterRegister(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("and %s, %s, %s", pattern.Destination, pattern.Source, pattern.Operand)
 		code := arm.AndRegisterRegister(pattern.Destination, pattern.Source, pattern.Operand)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Call.go b/src/arm/Call.go
index 8c1901f..7e18522 100644
--- a/src/arm/Call.go
+++ b/src/arm/Call.go
@@ -3,6 +3,6 @@ package arm
 // Call branches to a PC-relative offset, setting the register X30 to PC+4.
 // The offset starts from the address of this instruction and is encoded as "imm26" times 4.
 // This instruction is also known as BL (branch with link).
-func Call(offset uint32) uint32 {
-	return uint32(0b100101<<26) | offset
+func Call(offset int) uint32 {
+	return uint32(0b100101<<26) | uint32(offset&mask26)
 }
diff --git a/src/arm/Call_test.go b/src/arm/Call_test.go
new file mode 100644
index 0000000..7000e8f
--- /dev/null
+++ b/src/arm/Call_test.go
@@ -0,0 +1,25 @@
+package arm_test
+
+import (
+	"testing"
+
+	"git.urbach.dev/cli/q/src/arm"
+	"git.urbach.dev/go/assert"
+)
+
+func TestCall(t *testing.T) {
+	usagePatterns := []struct {
+		Offset int
+		Code   uint32
+	}{
+		{0, 0x94000000},
+		{1, 0x94000001},
+		{-1, 0x97FFFFFF},
+	}
+
+	for _, pattern := range usagePatterns {
+		t.Logf("bl %d", pattern.Offset)
+		code := arm.Call(pattern.Offset)
+		assert.Equal(t, code, pattern.Code)
+	}
+}
diff --git a/src/arm/Compare_test.go b/src/arm/Compare_test.go
index 4ed047c..ab4abdb 100644
--- a/src/arm/Compare_test.go
+++ b/src/arm/Compare_test.go
@@ -24,7 +24,7 @@ func TestCompareRegisterNumber(t *testing.T) {
 		t.Logf("cmp %s, %d", pattern.Source, pattern.Number)
 		code, encodable := arm.CompareRegisterNumber(pattern.Source, pattern.Number)
 		assert.True(t, encodable)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
 
@@ -40,6 +40,6 @@ func TestCompareRegisterRegister(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("cmp %s, %s", pattern.Left, pattern.Right)
 		code := arm.CompareRegisterRegister(pattern.Left, pattern.Right)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Div_test.go b/src/arm/Div_test.go
index 81c3f03..5d3f281 100644
--- a/src/arm/Div_test.go
+++ b/src/arm/Div_test.go
@@ -21,6 +21,6 @@ func TestDivSigned(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("sdiv %s, %s, %s", pattern.Destination, pattern.Source, pattern.Operand)
 		code := arm.DivSigned(pattern.Destination, pattern.Source, pattern.Operand)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Jump.go b/src/arm/Jump.go
index 8f3f807..a51eea9 100644
--- a/src/arm/Jump.go
+++ b/src/arm/Jump.go
@@ -2,42 +2,40 @@ package arm
 
 // Jump continues program flow at the new offset.
 func Jump(offset int) uint32 {
-	offset &= 0b11_1111_1111_1111_1111_1111_1111
-	return 0b000101<<26 | uint32(offset)
+	return 0b000101<<26 | uint32(offset&mask26)
 }
 
 // JumpIfEqual jumps if the result was equal.
 func JumpIfEqual(offset int) uint32 {
-	return branchCond(0b0000, offset)
+	return branchCond(EQ, offset)
 }
 
 // JumpIfNotEqual jumps if the result was not equal.
 func JumpIfNotEqual(offset int) uint32 {
-	return branchCond(0b0001, offset)
+	return branchCond(NE, offset)
 }
 
 // JumpIfGreater jumps if the result was greater.
 func JumpIfGreater(offset int) uint32 {
-	return branchCond(0b1100, offset)
+	return branchCond(GT, offset)
 }
 
 // JumpIfGreaterOrEqual jumps if the result was greater or equal.
 func JumpIfGreaterOrEqual(offset int) uint32 {
-	return branchCond(0b1010, offset)
+	return branchCond(GE, offset)
 }
 
 // JumpIfLess jumps if the result was less.
 func JumpIfLess(offset int) uint32 {
-	return branchCond(0b1001, offset)
+	return branchCond(LS, offset)
 }
 
 // JumpIfLessOrEqual jumps if the result was less or equal.
 func JumpIfLessOrEqual(offset int) uint32 {
-	return branchCond(0b1101, offset)
+	return branchCond(LE, offset)
 }
 
 // branchCond performs a conditional branch to a PC-relative offset.
-func branchCond(cond uint32, offset int) uint32 {
-	offset &= 0b111_1111_1111_1111_1111
-	return 0b01010100<<24 | uint32(offset)<<5 | cond
+func branchCond(cond condition, imm19 int) uint32 {
+	return 0b01010100<<24 | uint32(imm19&mask19)<<5 | uint32(cond)
 }
diff --git a/src/arm/Jump_test.go b/src/arm/Jump_test.go
index 423c568..651cdb0 100644
--- a/src/arm/Jump_test.go
+++ b/src/arm/Jump_test.go
@@ -63,6 +63,6 @@ func TestJump(t *testing.T) {
 			code = arm.JumpIfLessOrEqual(pattern.Offset)
 		}
 
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/LoadAddress_test.go b/src/arm/LoadAddress_test.go
index 3b3c05f..332b842 100644
--- a/src/arm/LoadAddress_test.go
+++ b/src/arm/LoadAddress_test.go
@@ -21,6 +21,6 @@ func TestLoadAddress(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("adr %s, %d", pattern.Destination, pattern.Number)
 		code := arm.LoadAddress(pattern.Destination, pattern.Number)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/LoadPair_test.go b/src/arm/LoadPair_test.go
index 97edbdb..0cd0448 100644
--- a/src/arm/LoadPair_test.go
+++ b/src/arm/LoadPair_test.go
@@ -23,6 +23,6 @@ func TestLoadPair(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("ldp %s, %s, [%s], #%d", pattern.Reg1, pattern.Reg2, pattern.Base, pattern.Offset)
 		code := arm.LoadPair(pattern.Reg1, pattern.Reg2, pattern.Base, pattern.Offset)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Load_test.go b/src/arm/Load_test.go
index 43eaf28..b8294f2 100644
--- a/src/arm/Load_test.go
+++ b/src/arm/Load_test.go
@@ -34,6 +34,6 @@ func TestLoadRegister(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("ldur %s, [%s, %d] %db", pattern.Destination, pattern.Base, pattern.Offset, pattern.Length)
 		code := arm.LoadRegister(pattern.Destination, pattern.Base, pattern.Offset, pattern.Length)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Move_test.go b/src/arm/Move_test.go
index acfb1a3..968cd1e 100644
--- a/src/arm/Move_test.go
+++ b/src/arm/Move_test.go
@@ -23,7 +23,7 @@ func TestMoveRegisterRegister(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("mov %s, %s", pattern.Destination, pattern.Source)
 		code := arm.MoveRegisterRegister(pattern.Destination, pattern.Source)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
 
@@ -79,7 +79,7 @@ func TestMoveRegisterNumberSI(t *testing.T) {
 
 		if pattern.Code != 0 {
 			assert.True(t, encodable)
-			assert.DeepEqual(t, code, pattern.Code)
+			assert.Equal(t, code, pattern.Code)
 		} else {
 			assert.False(t, encodable)
 		}
@@ -99,7 +99,7 @@ func TestMoveKeep(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("movk %s, %d", pattern.Register, pattern.Number)
 		code := arm.MoveKeep(pattern.Register, 0, pattern.Number)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
 
@@ -116,6 +116,6 @@ func TestMoveZero(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("movz %s, %d", pattern.Register, pattern.Number)
 		code := arm.MoveZero(pattern.Register, 0, pattern.Number)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Mul_test.go b/src/arm/Mul_test.go
index c59325e..3d9f5ca 100644
--- a/src/arm/Mul_test.go
+++ b/src/arm/Mul_test.go
@@ -21,7 +21,7 @@ func TestMulRegisterRegister(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("mul %s, %s, %s", pattern.Destination, pattern.Source, pattern.Operand)
 		code := arm.MulRegisterRegister(pattern.Destination, pattern.Source, pattern.Operand)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
 
@@ -40,6 +40,6 @@ func TestMultiplySubtract(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("msub %s, %s, %s, %s", pattern.Destination, pattern.Source, pattern.Operand, pattern.Extra)
 		code := arm.MultiplySubtract(pattern.Destination, pattern.Source, pattern.Operand, pattern.Extra)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Negate_test.go b/src/arm/Negate_test.go
index 65f3809..b5f385c 100644
--- a/src/arm/Negate_test.go
+++ b/src/arm/Negate_test.go
@@ -21,6 +21,6 @@ func TestNegateRegister(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("neg %s, %s", pattern.Destination, pattern.Source)
 		code := arm.NegateRegister(pattern.Destination, pattern.Source)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Or_test.go b/src/arm/Or_test.go
index 0d7aee9..98e6e8a 100644
--- a/src/arm/Or_test.go
+++ b/src/arm/Or_test.go
@@ -27,7 +27,7 @@ func TestOrRegisterNumber(t *testing.T) {
 		t.Logf("orr %s, %s, %d", pattern.Destination, pattern.Source, pattern.Number)
 		code, encodable := arm.OrRegisterNumber(pattern.Destination, pattern.Source, pattern.Number)
 		assert.True(t, encodable)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
 
@@ -44,6 +44,6 @@ func TestOrRegisterRegister(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("orr %s, %s, %s", pattern.Destination, pattern.Source, pattern.Operand)
 		code := arm.OrRegisterRegister(pattern.Destination, pattern.Source, pattern.Operand)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Shift_test.go b/src/arm/Shift_test.go
index 8aa96d2..556e349 100644
--- a/src/arm/Shift_test.go
+++ b/src/arm/Shift_test.go
@@ -26,7 +26,7 @@ func TestShiftLeftNumber(t *testing.T) {
 		t.Logf("%b", pattern.Code)
 		t.Logf("lsl %s, %s, %x", pattern.Destination, pattern.Source, pattern.Bits)
 		code := arm.ShiftLeftNumber(pattern.Destination, pattern.Source, pattern.Bits)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
 
@@ -47,6 +47,6 @@ func TestShiftRightSignedNumber(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("asr %s, %s, %x", pattern.Destination, pattern.Source, pattern.Bits)
 		code := arm.ShiftRightSignedNumber(pattern.Destination, pattern.Source, pattern.Bits)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/StorePair_test.go b/src/arm/StorePair_test.go
index eefdfbd..beca1bb 100644
--- a/src/arm/StorePair_test.go
+++ b/src/arm/StorePair_test.go
@@ -23,6 +23,6 @@ func TestStorePair(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("stp %s, %s, [%s, #%d]!", pattern.Reg1, pattern.Reg2, pattern.Base, pattern.Offset)
 		code := arm.StorePair(pattern.Reg1, pattern.Reg2, pattern.Base, pattern.Offset)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Store_test.go b/src/arm/Store_test.go
index 9f4150d..b83ebc6 100644
--- a/src/arm/Store_test.go
+++ b/src/arm/Store_test.go
@@ -29,6 +29,6 @@ func TestStoreRegister(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("stur %s, [%s, #%d] %db", pattern.Source, pattern.Base, pattern.Offset, pattern.Length)
 		code := arm.StoreRegister(pattern.Source, pattern.Base, pattern.Offset, pattern.Length)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Sub_test.go b/src/arm/Sub_test.go
index 2256704..0770b6a 100644
--- a/src/arm/Sub_test.go
+++ b/src/arm/Sub_test.go
@@ -24,7 +24,7 @@ func TestSubRegisterNumber(t *testing.T) {
 		t.Logf("sub %s, %s, %d", pattern.Destination, pattern.Source, pattern.Number)
 		code, encodable := arm.SubRegisterNumber(pattern.Destination, pattern.Source, pattern.Number)
 		assert.True(t, encodable)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
 
@@ -41,6 +41,6 @@ func TestSubRegisterRegister(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("sub %s, %s, %s", pattern.Destination, pattern.Source, pattern.Operand)
 		code := arm.SubRegisterRegister(pattern.Destination, pattern.Source, pattern.Operand)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/Xor_test.go b/src/arm/Xor_test.go
index c8f3dc5..aec2b42 100644
--- a/src/arm/Xor_test.go
+++ b/src/arm/Xor_test.go
@@ -27,7 +27,7 @@ func TestXorRegisterNumber(t *testing.T) {
 		t.Logf("eor %s, %s, %d", pattern.Destination, pattern.Source, pattern.Number)
 		code, encodable := arm.XorRegisterNumber(pattern.Destination, pattern.Source, pattern.Number)
 		assert.True(t, encodable)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
 
@@ -44,6 +44,6 @@ func TestXorRegisterRegister(t *testing.T) {
 	for _, pattern := range usagePatterns {
 		t.Logf("eor %s, %s, %s", pattern.Destination, pattern.Source, pattern.Operand)
 		code := arm.XorRegisterRegister(pattern.Destination, pattern.Source, pattern.Operand)
-		assert.DeepEqual(t, code, pattern.Code)
+		assert.Equal(t, code, pattern.Code)
 	}
 }
diff --git a/src/arm/arm_test.go b/src/arm/arm_test.go
index 9a6693f..12c6a4c 100644
--- a/src/arm/arm_test.go
+++ b/src/arm/arm_test.go
@@ -7,8 +7,7 @@ import (
 	"git.urbach.dev/go/assert"
 )
 
-func TestGeneral(t *testing.T) {
-	assert.DeepEqual(t, arm.Call(0), 0x94000000)
+func TestConstants(t *testing.T) {
 	assert.DeepEqual(t, arm.Nop(), 0xD503201F)
 	assert.DeepEqual(t, arm.Return(), 0xD65F03C0)
 	assert.DeepEqual(t, arm.Syscall(), 0xD4000001)
diff --git a/src/arm/bitmask.go b/src/arm/bitmask.go
index 19a65f8..ecf487d 100644
--- a/src/arm/bitmask.go
+++ b/src/arm/bitmask.go
@@ -24,7 +24,7 @@ func encodeLogicalImmediate(val uint) (N int, immr int, imms int, encodable bool
 		return 0, 0, 0, false
 	}
 
-	return N, immr, (imms & 0x3f), true
+	return N, immr, (imms & 0x3F), true
 }
 
 // clearTrailingOnes clears trailing one bits.
diff --git a/src/arm/condition.go b/src/arm/condition.go
new file mode 100644
index 0000000..a959c1a
--- /dev/null
+++ b/src/arm/condition.go
@@ -0,0 +1,22 @@
+package arm
+
+type condition uint8
+
+const (
+	EQ condition = iota
+	NE
+	CS
+	CC
+	MI
+	PL
+	VS
+	VC
+	HI
+	LS
+	GE
+	LT
+	GT
+	LE
+	AL
+	NV
+)
diff --git a/src/arm/encode.go b/src/arm/encode.go
index 0b9d45c..89ec099 100644
--- a/src/arm/encode.go
+++ b/src/arm/encode.go
@@ -4,14 +4,6 @@ import (
 	"git.urbach.dev/cli/q/src/cpu"
 )
 
-const (
-	mask6  = 0b111111
-	mask7  = 0b1111111
-	mask9  = 0b1_11111111
-	mask12 = 0b1111_11111111
-	mask16 = 0b11111111_11111111
-)
-
 // memory encodes an instruction with a register, a base register and an offset.
 func memory(destination cpu.Register, base cpu.Register, imm9 int) uint32 {
 	return uint32(imm9&mask9)<<12 | uint32(base)<<5 | uint32(destination)
diff --git a/src/arm/mask.go b/src/arm/mask.go
new file mode 100644
index 0000000..b1bb519
--- /dev/null
+++ b/src/arm/mask.go
@@ -0,0 +1,11 @@
+package arm
+
+const (
+	mask6  = 0b111111
+	mask7  = 0b1111111
+	mask9  = 0b1_11111111
+	mask12 = 0b1111_11111111
+	mask16 = 0b11111111_11111111
+	mask19 = 0b111_11111111_11111111
+	mask26 = 0b11_11111111_11111111_11111111
+)
diff --git a/src/asmc/armCompiler.go b/src/asmc/armCompiler.go
index 6c11240..0ce0434 100644
--- a/src/asmc/armCompiler.go
+++ b/src/asmc/armCompiler.go
@@ -100,10 +100,12 @@ func (c *armCompiler) handleCallInstruction(instruction asm.Instruction) {
 
 		pointer.Resolve = func() Address {
 			destination, exists := c.codeLabels[label.Name]
+
 			if !exists {
 				panic(fmt.Sprintf("unknown jump label %s", label.Name))
 			}
-			distance := (destination - position) / 4
+
+			distance := int(destination-position) / 4
 			return arm.Call(distance)
 		}