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

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

src/machine/flash.go

@@ -64,82 +64,3 @@ type BlockDevice interface {
 	// EraseBlockSize to map addresses to blocks.
 	EraseBlocks(start, len int64) error
 }
-
-// FlashBuffer implements the ReadWriteCloser interface using the BlockDevice interface.
-type FlashBuffer struct {
-	b BlockDevice
-
-	// start is actual address
-	start uintptr
-
-	// offset is relative to start
-	offset uintptr
-}
-
-// OpenFlashBuffer opens a FlashBuffer.
-func OpenFlashBuffer(b BlockDevice, address uintptr) *FlashBuffer {
-	return &FlashBuffer{b: b, start: address}
-}
-
-// Read data from a FlashBuffer.
-func (fl *FlashBuffer) Read(p []byte) (n int, err error) {
-	n, err = fl.b.ReadAt(p, int64(fl.offset))
-	fl.offset += uintptr(n)
-
-	return
-}
-
-// Write data to a FlashBuffer.
-func (fl *FlashBuffer) Write(p []byte) (n int, err error) {
-	// any new pages needed?
-	// NOTE probably will not work as expected if you try to write over page boundary
-	// of pages with different sizes.
-	pagesize := uintptr(fl.b.EraseBlockSize())
-
-	// calculate currentPageBlock relative to fl.start, meaning that
-	// block 0 -> fl.start
-	// block 1 -> fl.start + pagesize
-	// block 2 -> fl.start + pagesize*2
-	// ...
-	currentPageBlock := (fl.start + fl.offset - FlashDataStart()) + (pagesize-1)/pagesize
-	lastPageBlockNeeded := (fl.start + fl.offset + uintptr(len(p)) - FlashDataStart()) + (pagesize-1)/pagesize
-
-	// erase enough blocks to hold the data
-	if err := fl.b.EraseBlocks(int64(currentPageBlock), int64(lastPageBlockNeeded-currentPageBlock)); err != nil {
-		return 0, err
-	}
-
-	// write the data
-	for i := 0; i < len(p); i += int(pagesize) {
-		var last int = i + int(pagesize)
-		if i+int(pagesize) > len(p) {
-			last = len(p)
-		}
-
-		_, err := fl.b.WriteAt(p[i:last], int64(fl.offset))
-		if err != nil {
-			return 0, err
-		}
-		fl.offset += uintptr(len(p[i:last]))
-	}
-
-	return len(p), nil
-}
-
-// Close the FlashBuffer.
-func (fl *FlashBuffer) Close() error {
-	return nil
-}
-
-// Seek implements io.Seeker interface, but with limitations.
-// You can only seek relative to the start.
-// Also, you cannot use seek before write operations, only read.
-func (fl *FlashBuffer) Seek(offset int64, whence int) (int64, error) {
-	if whence != io.SeekStart {
-		panic("you can only Seek relative to Start")
-	}
-
-	fl.offset = uintptr(offset)
-
-	return offset, nil
-}