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Always set mode 2

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This commit is contained in:
Ryan Kennedy 2020-03-22 23:22:51 -05:00
parent c4486427c0
commit 4ab8f4d1d2
1 changed files with 17 additions and 5 deletions
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22
src/writers/graphics_640x480x16.rs
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@ -7,7 +7,7 @@ use spinning_top::SpinlockGuard;
const WIDTH: usize = 640; const WIDTH: usize = 640;
const HEIGHT: usize = 480; const HEIGHT: usize = 480;
const ALL_PLANES_SCREEN_SIZE: usize = (WIDTH * HEIGHT) / 4; const ALL_PLANES_SCREEN_SIZE: usize = (WIDTH * HEIGHT) / 8;
/// A basic interface for interacting with vga graphics mode 640x480x16 /// A basic interface for interacting with vga graphics mode 640x480x16
/// ///
@ -32,14 +32,17 @@ impl Graphics640x480x16 {
Graphics640x480x16 {} Graphics640x480x16 {}
} }
/// Clears the screen by setting all pixels to `Color16Bit::Black`. /// Clears the screen by setting all pixels to the specified `color`.
pub fn clear_screen(&self, color: Color16Bit) { pub fn clear_screen(&self, color: Color16Bit) {
let (mut vga, frame_buffer) = self.get_frame_buffer(); let (mut vga, frame_buffer) = self.get_frame_buffer();
vga.sequencer_registers // Set write mode 2 so data is modified by the bitmask
.set_plane_mask(PlaneMask::ALL_PLANES);
vga.graphics_controller_registers.set_bit_mask(0xFF);
vga.graphics_controller_registers vga.graphics_controller_registers
.set_write_mode(WriteMode::Mode2); .set_write_mode(WriteMode::Mode2);
// Write to all 4 planes at once
vga.sequencer_registers
.set_plane_mask(PlaneMask::ALL_PLANES);
// Every bit should be set to the same color
vga.graphics_controller_registers.set_bit_mask(0xFF);
for offset in 0..ALL_PLANES_SCREEN_SIZE { for offset in 0..ALL_PLANES_SCREEN_SIZE {
unsafe { unsafe {
frame_buffer.add(offset).write_volatile(u8::from(color)); frame_buffer.add(offset).write_volatile(u8::from(color));
@ -51,13 +54,22 @@ impl Graphics640x480x16 {
pub fn set_pixel(&self, x: usize, y: usize, color: Color16Bit) { pub fn set_pixel(&self, x: usize, y: usize, color: Color16Bit) {
let (mut vga, frame_buffer) = self.get_frame_buffer(); let (mut vga, frame_buffer) = self.get_frame_buffer();
let offset = x / 8 + (WIDTH / 8) * y; let offset = x / 8 + (WIDTH / 8) * y;
// Which pixel to modify this write
let pixel_offset = x & 7; let pixel_offset = x & 7;
// Set write mode 2 so screen data is only modified by the bitmask
vga.graphics_controller_registers vga.graphics_controller_registers
.set_write_mode(WriteMode::Mode2); .set_write_mode(WriteMode::Mode2);
// Write to all 4 planes at once
vga.sequencer_registers
.set_plane_mask(PlaneMask::ALL_PLANES);
// Only modify 1 pixel, based on the offset
vga.graphics_controller_registers vga.graphics_controller_registers
.set_bit_mask(1 << pixel_offset); .set_bit_mask(1 << pixel_offset);
unsafe { unsafe {
// Reads the current offset into the memory latches
frame_buffer.add(offset).read_volatile(); frame_buffer.add(offset).read_volatile();
// Sets the pixel specified by the offset to the color. The
// pixels not inlcuded in the bit mask remain untouched.
frame_buffer.add(offset).write_volatile(u8::from(color)); frame_buffer.add(offset).write_volatile(u8::from(color));
} }
} }