Merge gitlab.com/firelizzard/go-framebuffer

Author: firelizzard18

dev_fb.go

@@ -0,0 +1,182 @@
+package framebuffer
+
+import (
+	"os"
+	"syscall"
+)
+
+// FrameBuffer is a wrapper around [os.File] that provides convenience methods
+// for interacting with a frame buffer device.
+type FrameBuffer os.File
+
+// OpenFrameBuffer opens a frame buffer device.
+func OpenFrameBuffer(name string, flags int) (*FrameBuffer, error) {
+	f, err := os.OpenFile(name, flags, os.ModeDevice)
+	if err != nil {
+		return nil, err
+	}
+	return (*FrameBuffer)(f), nil
+}
+
+// File converts the frame buffer back to a file.
+func (fb *FrameBuffer) File() *os.File {
+	return (*os.File)(fb)
+}
+
+// Pixels returns a byte slice memory mapped to the frame buffer.
+func (fb *FrameBuffer) Pixels() ([]byte, error) {
+	vi, err := fb.VarScreenInfo()
+	if err != nil {
+		return nil, err
+	}
+
+	fd := fb.File().Fd()
+	length := vi.XRes * vi.YRes * vi.BitsPerPixel / 8
+	flags := syscall.PROT_READ | syscall.PROT_WRITE
+	return syscall.Mmap(int(fd), 0, int(length), flags, syscall.MAP_SHARED)
+}
+
+// FixScreenInfo returns the fixed properties of the screen.
+func (fb *FrameBuffer) FixScreenInfo() (FbFixScreenInfo, error) {
+	return ioctlGet[FbFixScreenInfo](fb.File(), kFBIOGET_FSCREENINFO)
+}
+
+// VarScreenInfo returns the variable properties of the screen.
+func (fb *FrameBuffer) VarScreenInfo() (FbVarScreenInfo, error) {
+	return ioctlGet[FbVarScreenInfo](fb.File(), kFBIOGET_VSCREENINFO)
+}
+
+// <linux/fb.h> ioctls
+//
+// 0x46 is 'F'
+const (
+	kFBIOGET_VSCREENINFO = 0x4600
+	kFBIOPUT_VSCREENINFO = 0x4601
+	kFBIOGET_FSCREENINFO = 0x4602
+)
+
+// <linux/fb.h> struct fb_fix_screeninfo
+//
+// Fixed parameters of a screen
+type FbFixScreenInfo struct {
+	// Screen ID, e.g. "TT Builtin"
+	ID [16]byte
+
+	// Frame buffer mem (physical address)
+	SMemStart uintptr
+	SMemLen   uint32
+
+	// Framebuffer type (see FB_TYPE_*)
+	Type uint32
+
+	// "Interleave for interleaved Planes"
+	TypeAux uint32
+
+	// ??? (see FB_VISUAL_)
+	Visual uint32
+
+	XPanStep  uint16
+	YPanStep  uint16
+	YWrapStep uint16
+
+	// Length of a line in bytes
+	LineLength uint32
+
+	// Memory mapped I/O (physical address)
+	MmioStart uintptr
+	MmioLen   uint32
+
+	// "Indicate to driver which specific chip/card we have"
+	Accel uint32
+
+	// Capabilities (see FB_CAP_*)
+	Capabilities uint16
+
+	// Reserved
+	_ [2]uint16
+}
+
+// <linux/fb.h> struct fb_fix_screeninfo
+//
+// Variable parameters of a screen
+type FbVarScreenInfo struct {
+	// Visible resolution
+	XRes, YRes uint32
+
+	// Virtual resolution
+	XResVirtual, YResVirtual uint32
+
+	// Offset from virtual to visible resolution
+	XOffset, YOffset uint32
+
+	// Number of bits per pixel in the buffer
+	BitsPerPixel uint32
+
+	// 0 = color, 1 = grayscale, >1 = FOURCC
+	Grayscale uint32
+
+	// Pixel format
+	Red, Green, Blue, Alpha FbBitField
+
+	// A value other than zero indicates a non-standard pixel format
+	NonStd uint32
+
+	// ??? (see FB_ACTIVATE_*)
+	Activate uint32
+
+	// Dimensions of picture in mm
+	Height, Width uint32
+
+	// Deprecated, used to be accel_flags (see fb_info.flags)
+	_ uint32
+
+	// Pixel clock in pico seconds
+	PixelClock uint32
+
+	// Time from sync to picture
+	LeftMargin uint32
+
+	// Time from picture to sync
+	RightMargin uint32
+
+	UpperMargin uint32
+	LowerMargin uint32
+
+	// Length of horizontal sync
+	HSyncLen uint32
+
+	// Length of vertical sync
+	VSyncLen uint32
+
+	// ??? (see FB_SYNC_*)
+	Sync uint32
+
+	// ??? (see FB_VMODE_*)
+	VMode uint32
+
+	// Angle we rotate counter clockwise
+	Rotate uint32
+
+	// Color space for FOURCC-based modes
+	ColorSpace uint32
+
+	// Reserved
+	_ [4]uint32
+}
+
+// <linux/fb.h> struct fb_bitfield
+//
+// Interpretation of offset for color fields: All offsets are from the right,
+// inside a "pixel" value, which is exactly 'bits_per_pixel' wide (means: you
+// can use the offset as right argument to <<). A pixel afterwards is a bit
+// stream and is written to video memory as that unmodified.
+//
+// For pseudocolor: offset and length should be the same for all color
+// components. Offset specifies the position of the least significant bit of the
+// palette index in a pixel value. Length indicates the number of available
+// palette entries (i.e. # of entries = 1 << length).
+type FbBitField struct {
+	Offset   uint32
+	Length   uint32
+	MsbRight uint32
+}

dev_tty.go

@@ -0,0 +1,68 @@
+package framebuffer
+
+import "os"
+
+// TTY is a wrapper around [os.File] that provides convenience methods for
+// interacting with a TTY.
+type TTY os.File
+
+// OpenMyTTY opens the current process's TTY. Requires procfs mounted at /proc.
+func OpenMyTTY(flags int) (*TTY, error) {
+	name, err := os.Readlink("/proc/self/fd/0")
+	if err != nil {
+		return nil, err
+	}
+	return OpenTTY(name, flags)
+}
+
+// OpenTTY opens a TTY.
+func OpenTTY(name string, flags int) (*TTY, error) {
+	f, err := os.OpenFile(name, flags, os.ModeDevice)
+	if err != nil {
+		return nil, err
+	}
+	return (*TTY)(f), nil
+}
+
+// File converts the TTY back to a file.
+func (d *TTY) File() *os.File {
+	return (*os.File)(d)
+}
+
+// TextMode puts the TTY in text mode.
+func (d *TTY) TextMode() error {
+	return d.SetMode(kKD_TEXT)
+}
+
+// GraphicsMode puts the TTY in graphics mode.
+func (d *TTY) GraphicsMode() error {
+	return d.SetMode(kKD_GRAPHICS)
+}
+
+// SetMode sets the TTY's mode.
+func (d *TTY) SetMode(mode TTYMode) error {
+	return ioctl(d.File(), kKDSETMODE, uintptr(mode))
+}
+
+// GetMode returns the TTY's current mode.
+func (d *TTY) GetMode() (TTYMode, error) {
+	return ioctlGet[TTYMode](d.File(), kKDGETMODE)
+}
+
+type TTYMode int
+
+const (
+	TTYTextMode     TTYMode = kKD_TEXT
+	TTYGraphicsMode TTYMode = kKD_GRAPHICS
+)
+
+// <linux/kd.h> ioctls
+//
+// 0x4B is 'K', to avoid collision with termios and vt
+const (
+	kKDSETMODE = 0x4B3A
+	kKDGETMODE = 0x4B3B
+
+	kKD_TEXT     = 0x00
+	kKD_GRAPHICS = 0x01
+)