check in sampler module

firmware/src/sampler.rs

@@ -0,0 +1,64 @@
+//! Driver for custom sampler peripheral
+
+use crate::{write_reg, read_reg};
+
+const BASE: u32 = 0x8040_0000;
+
+const REG_CR: u32 = 0x00;
+const REG_SR: u32 = 0x04;
+const REG_TRIGGER_RUN_LEN: u32 = 0x08;
+const REG_THRESH_VALUE: u32 = 0x0c;
+const REG_THRESH_PERIOD: u32 = 0x10;
+const REG_DECAY_VALUE: u32 = 0x14;
+const REG_DECAY_PERIOD: u32 = 0x18;
+
+const REG_BUFFER_LEN_OFFSET: u32 = 0x100 << 2;
+const SAMPLE_MEM_LEN: u32 = 0x8000 << 2;
+
+pub fn start_sampling() {
+    unsafe {
+        write_reg(BASE + REG_CR, 0x01);
+    }
+}
+
+pub fn stop_sampling() {
+    unsafe {
+        write_reg(BASE + REG_CR, 0x02);
+    }
+}
+
+pub fn clear_buffers() {
+    unsafe {
+        write_reg(BASE + REG_CR, 0x04);
+    }
+}
+
+#[derive(Clone, Copy, Debug)]
+pub struct Status {
+    pub capture_complete: bool,
+    pub sampling: bool,
+}
+
+pub fn read_status() -> Status {
+    unsafe {
+        let status: u32 = read_reg(BASE + REG_SR);
+
+        Status {
+            capture_complete: status & 0x01 != 0,
+            sampling: status & 0x02 != 0,
+        }
+    }
+}
+
+/// Get a slice of the sample buffer memory. Returns u32 because each sample is
+/// aligned to 32 bits, actual samples are 9 bits of real data.
+///
+/// SAFETY: This buffer can get cleared, so make sure you only read from it while
+/// it's valid, and also make sure the sampler index is not larger than the number
+/// of samplers (0-indexed).
+pub unsafe fn get_sample_buffer(sampler: u8) -> &'static [u32] {
+    let len: u32 = read_reg(BASE + REG_BUFFER_LEN_OFFSET + (sampler as u32 * 4));
+    let addr = BASE + SAMPLE_MEM_LEN * (sampler as u32 + 1);
+
+    core::slice::from_raw_parts(addr as *const u32, len as usize)
+}