machine/flash: remove FlashBuffer, modify flash example to use BlockDevice interface

Signed-off-by: deadprogram <ron@hybridgroup.com>

src/examples/flash/main.go

@@ -7,7 +7,10 @@ import (
 
 var (
 	err     error
-	message = "1234567887654321123456788765432112345678876543211234567887654321"
+	message = "1234567887654321123456788765432112345678876543211234567887654321" +
+		"1234567887654321123456788765432112345678876543211234567887654321" +
+		"1234567887654321123456788765432112345678876543211234567887654321" +
+		"1234567887654321123456788765432112345678876543211234567887654321"
 )
 
 func main() {
@@ -21,30 +24,54 @@ func main() {
 	println("Flash erase block size:", machine.Flash.EraseBlockSize())
 	println()
 
-	flash := machine.OpenFlashBuffer(machine.Flash, machine.FlashDataStart())
 	original := make([]byte, len(message))
 	saved := make([]byte, len(message))
 
 	// Read flash contents on start (data shall survive power off)
-	print("Reading data from flash: ")
-	_, err = flash.Read(original)
+	println("Reading original data from flash:")
+	_, err = machine.Flash.ReadAt(original, 0)
 	checkError(err)
 	println(string(original))
 
+	// erase flash
+	println("Erasing flash...")
+	needed := int64(len(message)) / machine.Flash.EraseBlockSize()
+	if needed == 0 {
+		// have to erase at least 1 block
+		needed = 1
+	}
+
+	err := machine.Flash.EraseBlocks(0, needed)
+	checkError(err)
+
 	// Write the message to flash
-	print("Writing data to flash: ")
-	flash.Seek(0, 0) // rewind back to beginning
-	_, err = flash.Write([]byte(message))
+	println("Writing new data to flash:")
+	_, err = machine.Flash.WriteAt([]byte(message), 0)
 	checkError(err)
 	println(string(message))
 
 	// Read back flash contents after write (verify data is the same as written)
-	print("Reading data back from flash: ")
-	flash.Seek(0, 0) // rewind back to beginning
-	_, err = flash.Read(saved)
+	println("Reading data back from flash: ")
+	_, err = machine.Flash.ReadAt(saved, 0)
 	checkError(err)
+	if !equal(saved, []byte(message)) {
+		println("data verify error")
+	}
+
 	println(string(saved))
-	println()
+	println("Done.")
+}
+
+func equal(a, b []byte) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i, v := range a {
+		if v != b[i] {
+			return false
+		}
+	}
+	return true
 }
 
 func checkError(err error) {