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st7789: avoid heap allocations after the driver is created #545

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Merged
merged 1 commit into from
Apr 14, 2023
Merged

st7789: avoid heap allocations after the driver is created #545

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27 changes: 17 additions & 10 deletions st7789/st7789.go
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,7 @@ type Device struct {
batchLength int32
isBGR bool
vSyncLines int16
buf [6]byte
}

// Config is the configuration for the display
Expand Down Expand Up @@ -262,10 +263,12 @@ func (d *Device) SetPixel(x int16, y int16, c color.RGBA) {
func (d *Device) setWindow(x, y, w, h int16) {
x += d.columnOffset
y += d.rowOffset
d.Tx([]uint8{CASET}, true)
d.Tx([]uint8{uint8(x >> 8), uint8(x), uint8((x + w - 1) >> 8), uint8(x + w - 1)}, false)
d.Tx([]uint8{RASET}, true)
d.Tx([]uint8{uint8(y >> 8), uint8(y), uint8((y + h - 1) >> 8), uint8(y + h - 1)}, false)
d.Command(CASET)
copy(d.buf[:4], []uint8{uint8(x >> 8), uint8(x), uint8((x + w - 1) >> 8), uint8(x + w - 1)})
d.Tx(d.buf[:4], false)
d.Command(RASET)
copy(d.buf[:4], []uint8{uint8(y >> 8), uint8(y), uint8((y + h - 1) >> 8), uint8(y + h - 1)})
d.Tx(d.buf[:4], false)
d.Command(RAMWR)
}

Expand Down Expand Up @@ -404,12 +407,14 @@ func (d *Device) SetRotation(rotation Rotation) {

// Command sends a command to the display.
func (d *Device) Command(command uint8) {
d.Tx([]byte{command}, true)
d.buf[0] = command
d.Tx(d.buf[:1], true)
}

// Data sends data to the display.
func (d *Device) Data(data uint8) {
d.Tx([]byte{data}, false)
d.buf[0] = data
d.Tx(d.buf[:1], false)
}

// Tx sends data to the display
Expand Down Expand Up @@ -470,17 +475,19 @@ func (d *Device) IsBGR(bgr bool) {
// SetScrollArea sets an area to scroll with fixed top and bottom parts of the display.
func (d *Device) SetScrollArea(topFixedArea, bottomFixedArea int16) {
d.Command(VSCRDEF)
d.Tx([]uint8{
copy(d.buf[:6], []uint8{
uint8(topFixedArea >> 8), uint8(topFixedArea),
uint8(d.height - topFixedArea - bottomFixedArea>>8), uint8(d.height - topFixedArea - bottomFixedArea),
uint8(bottomFixedArea >> 8), uint8(bottomFixedArea)},
false)
uint8(bottomFixedArea >> 8), uint8(bottomFixedArea)})
d.Tx(d.buf[:6], false)
}

// SetScroll sets the vertical scroll address of the display.
func (d *Device) SetScroll(line int16) {
d.Command(VSCRSADD)
d.Tx([]uint8{uint8(line >> 8), uint8(line)}, false)
d.buf[0] = uint8(line >> 8)
d.buf[1] = uint8(line)
d.Tx(d.buf[:2], false)
}

// StopScroll returns the display to its normal state.
Expand Down