Add slice write support

.gitignore

@@ -7,6 +7,9 @@
 _obj
 _test
 
+# intellij idea files
+.idea
+
 # Architecture specific extensions/prefixes
 *.[568vq]
 [568vq].out

MCP23S17/MCP23S17.go

@@ -2,6 +2,7 @@ package MCP23S17
 
 import (
 	"fmt"
+
 	"github.com/luismesas/goPi/spi"
 )
 
@@ -62,7 +63,7 @@ type MCP23S17 struct {
 
 func NewMCP23S17(hardwareAddress uint8, bus int, chip_select int) *MCP23S17 {
 	mcp := new(MCP23S17)
-	mcp.Device = spi.NewSPIDevice(bus, chip_select)
+	mcp.Device = spi.NewSPIDevice(bus, chip_select, spi.SPI_DELAY)
 	mcp.HardwareAddress = hardwareAddress
 
 	mcp.IODIRa = NewMCP23S17Register(IODIRA, mcp)
@@ -141,7 +142,7 @@ func (mcp *MCP23S17) getSPIControlByte(read_write_cmd uint8) byte {
 // Returns the value of the address specified.
 func (mcp *MCP23S17) Read(address byte) byte {
 	ctrl_byte := mcp.getSPIControlByte(READ_CMD)
-	data, err := mcp.Device.Send([3]byte{ctrl_byte, address, 0})
+	data, err := mcp.Device.Send([]byte{ctrl_byte, address, 0})
 	if err != nil {
 		panic(fmt.Sprintf("Error reading from MCP23S17: %s\n", err))
 		return 0x00
@@ -155,7 +156,7 @@ func (mcp *MCP23S17) Read(address byte) byte {
 // Writes data to the address specified.
 func (mcp *MCP23S17) Write(data byte, address byte) {
 	ctrl_byte := mcp.getSPIControlByte(WRITE_CMD)
-	_, err := mcp.Device.Send([3]byte{ctrl_byte, address, data})
+	_, err := mcp.Device.Send([]byte{ctrl_byte, address, data})
 	if err != nil {
 		panic(fmt.Sprintf("Error writing on MCP23S17: %s\n", err))
 	}

examples/blink_MCP23S17/blink_MCP23S17.go

@@ -1,10 +1,11 @@
 package main
 
 import (
-	"github.com/luismesas/goPi/MCP23S17"
-	"github.com/luismesas/goPi/spi"
 	"log"
 	"time"
+
+	"github.com/luismesas/goPi/MCP23S17"
+	"github.com/luismesas/goPi/spi"
 )
 
 func main() {

examples/blink_piface/blink_piface.go

@@ -2,9 +2,10 @@ package main
 
 import (
 	"fmt"
+	"time"
+
 	"github.com/luismesas/goPi/piface"
 	"github.com/luismesas/goPi/spi"
-	"time"
 )
 
 func main() {

piface/piface.go

@@ -1,22 +1,21 @@
-/* 
-Package piface is for interfacing with a PiFace Digital IO board. 
+/*
+Package piface is for interfacing with a PiFace Digital IO board.
 
  - More Info at http://www.piface.org.uk/products/piface_digital/
  - Guides at http://prod.www.piface.org.uk/guides/
  - goPi blink example at  https://github.com/luismesas/goPi/blob/master/examples/blink_piface/blink_piface.go
 
 Its possible to connect up to four PiFace boards to a Raspberry Pi, however some jumper
-settings are required to set the hardware address. 
+settings are required to set the hardware address.
 
  - See http://prod.www.piface.org.uk/guides/howto/PiFace_Digital_Jumper_Settings/
 
 */
 package piface
 
-
-
 import (
 	"fmt"
+
 	"github.com/luismesas/goPi/MCP23S17"
 )
 

rpi.go

@@ -1,11 +1,10 @@
-
 // Package rpi is a library for interfacing with Raspberry Pi IO
 package rpi
 
-// This is the wrong url here ??? 
+// This is the wrong url here ???
 import (
 	_ "github.com/luismesas/goPi/MCP23S17"
 	_ "github.com/luismesas/goPi/ioctl"
-	_ "github.com/luismesas/goPi/spi"
 	_ "github.com/luismesas/goPi/piface"
+	_ "github.com/luismesas/goPi/spi"
 )

spi/SPIDevice.go

@@ -2,9 +2,10 @@ package spi
 
 import (
 	"fmt"
-	"github.com/luismesas/goPi/ioctl"
 	"os"
 	"unsafe"
+
+	"github.com/luismesas/goPi/ioctl"
 )
 
 const SPIDEV = "/dev/spidev"
@@ -26,13 +27,15 @@ type SPIDevice struct {
 	mode  uint8
 	bpw   uint8
 	speed uint32
+	delay uint16
 }
 
 // An SPI Device at /dev/spi<bus>.<chip_select>.
-func NewSPIDevice(bus int, chipSelect int) *SPIDevice {
+func NewSPIDevice(bus int, chipSelect int, delayUsec uint16) *SPIDevice {
 	spi := new(SPIDevice)
 	spi.Bus = bus
 	spi.Chip = chipSelect
+	spi.delay = delayUsec
 
 	return spi
 }
@@ -61,16 +64,16 @@ func (spi *SPIDevice) Close() error {
 }
 
 // Sends bytes over SPI channel and returns []byte response
-func (spi *SPIDevice) Send(bytes_to_send [3]byte) ([]byte, error) {
-	wBuffer := bytes_to_send
-	rBuffer := [3]byte{}
+func (spi *SPIDevice) Send(wBuffer []byte) ([]byte, error) {
+	length := len(wBuffer)
+	rBuffer := make([]byte, length)
 
 	// generates message
 	transfer := SPI_IOC_TRANSFER{}
-	transfer.txBuf = uint64(uintptr(unsafe.Pointer(&wBuffer)))
-	transfer.rxBuf = uint64(uintptr(unsafe.Pointer(&rBuffer)))
-	transfer.length = uint32(unsafe.Sizeof(wBuffer))
-	transfer.delayUsecs = SPI_DELAY
+	transfer.txBuf = uint64(uintptr(unsafe.Pointer(&wBuffer[0])))
+	transfer.rxBuf = uint64(uintptr(unsafe.Pointer(&rBuffer[0])))
+	transfer.length = uint32(length)
+	transfer.delayUsecs = spi.delay
 	transfer.bitsPerWord = spi.bpw
 	transfer.speedHz = spi.speed
 
@@ -80,13 +83,7 @@ func (spi *SPIDevice) Send(bytes_to_send [3]byte) ([]byte, error) {
 		return nil, fmt.Errorf("Error on sending: %s\n", err)
 	}
 
-	// generates a valid response
-	ret := make([]byte, unsafe.Sizeof(rBuffer))
-	for i := range ret {
-		ret[i] = rBuffer[i]
-	}
-
-	return ret, nil
+	return rBuffer, nil
 }
 
 func (spi *SPIDevice) SetMode(mode uint8) error {

spi/spi.go

@@ -1,8 +1,9 @@
 package spi
 
 import (
-	"github.com/luismesas/goPi/ioctl"
 	"unsafe"
+
+	"github.com/luismesas/goPi/ioctl"
 )
 
 const SPI_IOC_MAGIC = 107