Extract magic numbers to named constants

pkg/jiecang/common.go

@@ -12,7 +12,7 @@ func isValidData(buf []byte) bool {
 	}
 
 	// Check preamble and last byte
-	if buf[0] != 0xf2 || buf[1] != 0xf2 || buf[len(buf)-1] != 0x7e {
+	if buf[0] != ProtocolResponse1 || buf[1] != ProtocolResponse2 || buf[len(buf)-1] != ProtocolTerminator {
 		return false
 	}
 

pkg/jiecang/height.go

@@ -26,20 +26,20 @@ func (j *Jiecang) GoToHeight(ctx context.Context, height uint8) error {
 	if height > j.HighestHeight || height < j.LowestHeight {
 		return fmt.Errorf("height %d is out of range (low: %d, high: %d)", height, j.LowestHeight, j.HighestHeight)
 	}
-	data0 := byte((int(height) * 10) / 256)
-	data1 := byte((int(height) * 10) % 256)
+	data0 := byte((int(height) * HeightConversionFactor) / 256)
+	data1 := byte((int(height) * HeightConversionFactor) % 256)
 	command := []byte{
-		0xf1,
-		0xf1,
+		ProtocolPreamble1,
+		ProtocolPreamble2,
 		0x1b,
 		0x02,
 		data0,
 		data1,
 		byte((int(0x1b) + int(0x02) + int(data0) + int(data1)) % 256),
-		0x7e,
+		ProtocolTerminator,
 	}
 
-	ticker := time.NewTicker(200 * time.Millisecond)
+	ticker := time.NewTicker(PollingInterval)
 	defer ticker.Stop()
 
 	for {
@@ -107,7 +107,7 @@ func readHeight(buf []byte) uint8 {
 	if buf[3] == 0x03 {
 		height := int(buf[4])*256 + int(buf[5])
 		// Hack to round the value
-		return uint8(math.Round(float64(height / 10.0)))
+		return uint8(math.Round(float64(height / HeightConversionFactor)))
 	}
 	return 0
 }
@@ -117,8 +117,8 @@ func readHeightRange(buf []byte) (uint8, uint8) {
 	if buf[3] == 0x04 {
 		highestHeight := int(buf[4])*256 + int(buf[5])
 		lowestHeight := int(buf[6])*256 + int(buf[7])
-		return uint8(math.Round(float64(highestHeight / 10.0))),
-			uint8(math.Round(float64(lowestHeight / 10.0)))
+		return uint8(math.Round(float64(highestHeight / HeightConversionFactor))),
+			uint8(math.Round(float64(lowestHeight / HeightConversionFactor)))
 	}
 	return 0, 0
 }

pkg/jiecang/jiecang.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"log"
 	"sync"
+	"time"
 
 	"tinygo.org/x/bluetooth"
 )
@@ -26,9 +27,29 @@ var commands = map[string][]byte{
 }
 
 const (
+	// BLE service and characteristic IDs
 	BLEDeviceId      = 0xFE60
 	BLECharDataInId  = 0xFE61
 	BLECharDataOutId = 0xFE62
+
+	// Protocol constants
+	ProtocolPreamble1  = 0xf1 // Command message preamble byte 1
+	ProtocolPreamble2  = 0xf1 // Command message preamble byte 2
+	ProtocolResponse1  = 0xf2 // Response message preamble byte 1
+	ProtocolResponse2  = 0xf2 // Response message preamble byte 2
+	ProtocolTerminator = 0x7e // Message terminator
+
+	// Conversion factors
+	HeightConversionFactor = 10 // Multiply height by 10 for protocol
+
+	// Memory preset constants
+	MemoryPresetModulo = 0x24 // Modulo for memory preset calculation
+
+	// Timing constants
+	PollingInterval     = 200 * time.Millisecond // Polling interval for height operations
+	SaveMemoryDelay     = 200 * time.Millisecond // Delay after saving memory preset
+	OperationTimeout    = 60 * time.Second       // Default timeout for operations
+	InitializationDelay = 200 * time.Millisecond // Delay during initialization
 )
 
 type Jiecang struct {
@@ -196,7 +217,7 @@ func (j *Jiecang) characteristicReceiver(buf []byte) {
 				j.HighestHeight, j.LowestHeight = readHeightRange(msg[i])
 				j.mu.Unlock()
 			case 0x25, 0x26, 0x27, 0x28: // Data contains height for each memory preset (1-4). Memory 4 is currently 0
-				memory := int(msg[i][2] % 0x24)
+				memory := int(msg[i][2] % MemoryPresetModulo)
 				memoryName := fmt.Sprintf("memory%d", memory)
 				j.mu.Lock()
 				j.presets[memoryName] = readMemoryPreset(msg[i])

pkg/jiecang/memory.go

@@ -15,7 +15,7 @@ func (j *Jiecang) GoToMemory1(ctx context.Context) error {
 		return fmt.Errorf("failed to send goto memory1 command: %w", err)
 	}
 
-	ticker := time.NewTicker(200 * time.Millisecond)
+	ticker := time.NewTicker(PollingInterval)
 	defer ticker.Stop()
 
 	for {
@@ -48,7 +48,7 @@ func (j *Jiecang) GoToMemory2(ctx context.Context) error {
 		return fmt.Errorf("failed to send goto memory2 command: %w", err)
 	}
 
-	ticker := time.NewTicker(200 * time.Millisecond)
+	ticker := time.NewTicker(PollingInterval)
 	defer ticker.Stop()
 
 	for {
@@ -81,7 +81,7 @@ func (j *Jiecang) GoToMemory3(ctx context.Context) error {
 		return fmt.Errorf("failed to send goto memory3 command: %w", err)
 	}
 
-	ticker := time.NewTicker(200 * time.Millisecond)
+	ticker := time.NewTicker(PollingInterval)
 	defer ticker.Stop()
 
 	for {
@@ -117,7 +117,7 @@ func (j *Jiecang) SaveMemory1() error {
 	}
 
 	log.Printf("Height: %d cm", j.currentHeight)
-	time.Sleep(200 * time.Millisecond)
+	time.Sleep(SaveMemoryDelay)
 	return nil
 }
 
@@ -128,7 +128,7 @@ func (j *Jiecang) SaveMemory2() error {
 	}
 
 	log.Printf("Height: %d cm", j.currentHeight)
-	time.Sleep(200 * time.Millisecond)
+	time.Sleep(SaveMemoryDelay)
 	return nil
 }
 
@@ -139,7 +139,7 @@ func (j *Jiecang) SaveMemory3() error {
 	}
 
 	log.Printf("Height: %d cm", j.currentHeight)
-	time.Sleep(200 * time.Millisecond)
+	time.Sleep(SaveMemoryDelay)
 	return nil
 }
 
@@ -149,7 +149,7 @@ func readMemoryPreset(buf []byte) uint8 {
 	if buf[3] == 0x02 {
 		preset := int(buf[4])*256 + int(buf[5])
 		// Hack to round the value
-		return uint8(math.Round(float64(preset / 10.0)))
+		return uint8(math.Round(float64(preset / HeightConversionFactor)))
 	}
 	return 0
 }