machine/atsam*, nrf, rp2040, stm32: correct error flashBlockDevice pad() function

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

src/machine/machine_atsamd21.go

@@ -1910,12 +1910,12 @@ func (f flashBlockDevice) EraseBlocks(start, len int64) error {
 
 // pad data if needed so it is long enough for correct byte alignment on writes.
 func (f flashBlockDevice) pad(p []byte) []byte {
-	paddingNeeded := f.WriteBlockSize() - (int64(len(p)) % f.WriteBlockSize())
+	overflow := int64(len(p)) % f.WriteBlockSize()
-	if paddingNeeded == 0 {
+	if overflow == 0 {
 		return p
 	}
 
-	padding := bytes.Repeat([]byte{0xff}, int(paddingNeeded))
+	padding := bytes.Repeat([]byte{0xff}, int(f.WriteBlockSize()-overflow))
 	return append(p, padding...)
 }
 

src/machine/machine_atsamd51.go

@@ -2239,12 +2239,12 @@ func (f flashBlockDevice) EraseBlocks(start, len int64) error {
 
 // pad data if needed so it is long enough for correct byte alignment on writes.
 func (f flashBlockDevice) pad(p []byte) []byte {
-	paddingNeeded := f.WriteBlockSize() - (int64(len(p)) % f.WriteBlockSize())
+	overflow := int64(len(p)) % f.WriteBlockSize()
-	if paddingNeeded == 0 {
+	if overflow == 0 {
 		return p
 	}
 
-	padding := bytes.Repeat([]byte{0xff}, int(paddingNeeded))
+	padding := bytes.Repeat([]byte{0xff}, int(f.WriteBlockSize()-overflow))
 	return append(p, padding...)
 }
 

src/machine/machine_nrf.go

@@ -396,12 +396,12 @@ func (f flashBlockDevice) EraseBlocks(start, len int64) error {
 
 // pad data if needed so it is long enough for correct byte alignment on writes.
 func (f flashBlockDevice) pad(p []byte) []byte {
-	paddingNeeded := f.WriteBlockSize() - (int64(len(p)) % f.WriteBlockSize())
+	overflow := int64(len(p)) % f.WriteBlockSize()
-	if paddingNeeded == 0 {
+	if overflow == 0 {
 		return p
 	}
 
-	padding := bytes.Repeat([]byte{0xff}, int(paddingNeeded))
+	padding := bytes.Repeat([]byte{0xff}, int(f.WriteBlockSize()-overflow))
 	return append(p, padding...)
 }
 

src/machine/machine_rp2040_rom.go

@@ -236,12 +236,12 @@ func (f flashBlockDevice) EraseBlocks(start, length int64) error {
 
 // pad data if needed so it is long enough for correct byte alignment on writes.
 func (f flashBlockDevice) pad(p []byte) []byte {
-	paddingNeeded := f.WriteBlockSize() - (int64(len(p)) % f.WriteBlockSize())
+	overflow := int64(len(p)) % f.WriteBlockSize()
-	if paddingNeeded == 0 {
+	if overflow == 0 {
 		return p
 	}
 
-	padding := bytes.Repeat([]byte{0xff}, int(paddingNeeded))
+	padding := bytes.Repeat([]byte{0xff}, int(f.WriteBlockSize()-overflow))
 	return append(p, padding...)
 }
 

src/machine/machine_stm32_flash.go

@@ -92,13 +92,13 @@ func (f flashBlockDevice) EraseBlocks(start, len int64) error {
 
 // pad data if needed so it is long enough for correct byte alignment on writes.
 func (f flashBlockDevice) pad(p []byte) []byte {
-	paddingNeeded := f.WriteBlockSize() - (int64(len(p)) % f.WriteBlockSize())
+	overflow := int64(len(p)) % f.WriteBlockSize()
-	if paddingNeeded == 0 {
+	if overflow == 0 {
 		return p
 	}
 
-	padded := bytes.Repeat([]byte{0xff}, int(paddingNeeded))
+	padding := bytes.Repeat([]byte{0xff}, int(f.WriteBlockSize()-overflow))
-	return append(p, padded...)
+	return append(p, padding...)
 }
 
 const memoryStart = 0x08000000