1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
//! Framebuffer: mmap'd `/dev/fb0` with MXCFB e-ink refresh.
//!
//! Takes raw `&[u8]` RGB565 buffers (2 bytes/pixel, little-endian) so the
//! caller is not locked into a specific pixel wrapper type (slint's
//! `Rgb565Pixel`, a plain `u16` newtype, etc.). The app crate provides a
//! `rgb565_as_bytes_ref` helper to convert from `&[Rgb565Pixel]` at the
//! call site.
use crate::rendering::eink::{
FbFixScreeninfo, FbVarScreeninfo, MxcfbRect, MxcfbUpdateData, FBIOGET_FSCREENINFO,
FBIOGET_VSCREENINFO, MXCFB_SEND_UPDATE,
};
use log::{debug, info, warn};
pub fn dump_ppm(path: &str, buf: &[u8], w: usize, h: usize) {
let mut out = Vec::with_capacity(15 + w * h * 3);
out.extend_from_slice(format!("P6\n{} {}\n255\n", w, h).as_bytes());
for i in 0..w * h {
let off = i * 2;
let v = (buf[off] as u16) | ((buf[off + 1] as u16) << 8);
let r = ((v >> 11) & 0x1f) as u8;
let g = ((v >> 5) & 0x3f) as u8;
let b = (v & 0x1f) as u8;
out.push((r << 3) | (r >> 2));
out.push((g << 2) | (g >> 4));
out.push((b << 3) | (b >> 2));
}
match std::fs::write(path, &out) {
Ok(_) => debug!("wrote {} ({} bytes)", path, out.len()),
Err(e) => warn!("PPM write err: {}", e),
}
}
pub struct Fb {
_file: std::fs::File,
pub fd: libc::c_int,
pub ptr: *mut u8,
pub map_len: usize,
pub stride: usize,
pub bpp: usize,
pub xres: usize,
pub yres: usize,
r_off: u32,
g_off: u32,
b_off: u32,
}
impl Fb {
pub fn open() -> Option<Fb> {
use std::os::unix::io::AsRawFd;
let file = std::fs::OpenOptions::new()
.read(true)
.write(true)
.open("/dev/fb0")
.ok()?;
let fd = file.as_raw_fd();
let mut var = FbVarScreeninfo::default();
let mut fix = FbFixScreeninfo::default();
// SAFETY: fd is a valid /dev/fb0 descriptor (file alive on this frame). FBIOGET_* read
// one fb_var/fb_fix screeninfo into the supplied &mut; both are #[repr(C)] structs of
// the kernel-expected layout, exclusively borrowed. A failing ioctl returns <0 and we
// bail; on success the structs are fully overwritten with valid values.
unsafe {
if libc::ioctl(fd, FBIOGET_VSCREENINFO as _, &mut var) < 0 {
return None;
}
if libc::ioctl(fd, FBIOGET_FSCREENINFO as _, &mut fix) < 0 {
return None;
}
}
let map_len = fix.smem_len as usize;
// SAFETY: mmap of the framebuffer with MAP_SHARED over the valid fd. map_len comes
// straight from the kernel's fix.smem_len. NULL addr = kernel picks. We check for
// MAP_FAILED immediately and bail; the returned pointer is the device-backed mapping
// owned by Fb (unmapped in Drop).
let ptr = unsafe {
libc::mmap(
std::ptr::null_mut(),
map_len,
libc::PROT_READ | libc::PROT_WRITE,
libc::MAP_SHARED,
fd,
0,
)
};
if ptr == libc::MAP_FAILED {
return None;
}
info!(
"fb: {}x{} bpp={} line_length={} smem_len={}",
var.xres, var.yres, var.bits_per_pixel, fix.line_length, fix.smem_len
);
let (r_off, g_off, b_off) = (
var.rest.first().copied().unwrap_or(16),
var.rest.get(3).copied().unwrap_or(8),
var.rest.get(6).copied().unwrap_or(0),
);
info!("fb: rgb offsets r={} g={} b={}", r_off, g_off, b_off);
Some(Fb {
_file: file,
fd,
ptr: ptr as *mut u8,
map_len,
stride: fix.line_length as usize,
bpp: var.bits_per_pixel as usize,
xres: var.xres as usize,
yres: var.yres as usize,
r_off,
g_off,
b_off,
})
}
/// Blit an RGB565 byte buffer to the framebuffer and trigger an e-ink
/// refresh. `buf` is `w * h * 2` bytes, little-endian RGB565.
pub fn present(
&self,
buf: &[u8],
w: usize,
h: usize,
full: bool,
top: usize,
rh: usize,
waveform: u32,
) {
// SAFETY: self.ptr is the mmap'd framebuffer of length self.map_len (set in open(),
// unmapped in Drop). We hold &self (shared) but only write fb pixels here - no other
// aliasing byte slice of this mapping is live concurrently. The slice length is exactly
// map_len, matching the mapping.
let fb = unsafe { std::slice::from_raw_parts_mut(self.ptr, self.map_len) };
let bpp = self.bpp;
let stride = self.stride;
let (y0, y1) = if full {
(0, h.min(self.yres))
} else {
let end = (top + rh).min(h).min(self.yres);
(top.min(end), end)
};
let x1 = w.min(self.xres);
for y in y0..y1 {
let row = y * w;
let fb_row = y * stride;
for x in 0..x1 {
let buf_off = (row + x) * 2;
let px = (buf[buf_off] as u16) | ((buf[buf_off + 1] as u16) << 8);
let off = fb_row + x * (bpp / 8);
match bpp {
32 => {
let r = (((px >> 11) & 0x1f) << 3) as u8;
let g = (((px >> 5) & 0x3f) << 2) as u8;
let b = ((px & 0x1f) << 3) as u8;
fb[off + (self.r_off / 8) as usize] = r;
fb[off + (self.g_off / 8) as usize] = g;
fb[off + (self.b_off / 8) as usize] = b;
fb[off + 3] = 0xff;
}
16 => {
fb[off] = (px & 0xff) as u8;
fb[off + 1] = (px >> 8) as u8;
}
_ => {}
}
}
}
let sync_start = y0 * self.stride;
let sync_len = ((y1 - y0) * self.stride).max(1);
// SAFETY: self.ptr.add(sync_start) stays within [self.ptr, self.ptr+map_len) because
// sync_start = y0*stride and sync_len = (y1-y0)*stride, with y0/y1 clamped to yres and
// stride*xres*... <= map_len for a linear framebuffer. MS_SYNC flushes the dirty pages.
unsafe {
libc::msync(
self.ptr.add(sync_start) as *mut libc::c_void,
sync_len,
libc::MS_SYNC,
);
}
let upd = MxcfbUpdateData {
update_region: MxcfbRect {
top: y0 as u32,
left: 0,
width: x1 as u32,
height: (y1 - y0) as u32,
},
waveform_mode: waveform,
update_mode: if full { 1 } else { 0 },
update_marker: 1,
temp: 0x1000,
flags: 0,
};
// SAFETY: MXCFB_SEND_UPDATE ioctl reads one #[repr(C)] MxcfbUpdateData from the &upd
// pointer (fully initialized above) to schedule the e-ink refresh. self.fd is the
// valid fb0 descriptor; a failing ioctl returns <0 (logged) and is non-fatal.
let rc = unsafe { libc::ioctl(self.fd, MXCFB_SEND_UPDATE as _, &upd) };
debug!(
"eink refresh (GC16 {} rows=[{},{}] {}x{}) rc={}",
if full { "FULL" } else { "PARTIAL" },
y0,
y1,
x1,
y1 - y0,
rc
);
}
}
impl Drop for Fb {
fn drop(&mut self) {
// SAFETY: self.ptr/self.map_len describe the single mmap acquired in open(); Drop runs
// once, no other reference to the mapping exists (file dropped right after), so
// munmap is sound and releases the device mapping.
unsafe {
libc::munmap(self.ptr as *mut libc::c_void, self.map_len);
}
}
}