From e946f2e9f1be0a9b0de56c62203c05de1b0f325f Mon Sep 17 00:00:00 2001
From: Matt Johnston <matt@ucc.asn.au>
Date: Wed, 5 Oct 2022 22:00:13 +0800
Subject: [PATCH] rename to "noise"
---
examples/{raw.rs => noise.rs} | 3 +-
src/cap.rs | 52 +++++++++++++++++++++++------------
src/lib.rs | 2 +-
src/rng.rs | 2 +-
4 files changed, 39 insertions(+), 20 deletions(-)
rename examples/{raw.rs => noise.rs} (89%)
diff --git a/examples/raw.rs b/examples/noise.rs
similarity index 89%
rename from examples/raw.rs
rename to examples/noise.rs
index 3eac6e8..24e83a1 100644
--- a/examples/raw.rs
+++ b/examples/noise.rs
@@ -23,7 +23,8 @@ async fn main(_spawner: Spawner) {
let mut cp = cortex_m::peripheral::Peripherals::take().unwrap();
let mut gpio = (Flex::new(p.PIN_10), 10);
- caprand::cap_rand(&mut gpio.0, gpio.1, &mut cp.SYST,
+ // let mut gpio = (Flex::new(p.PIN_22), 22);
+ caprand::noise(&mut gpio.0, gpio.1, &mut cp.SYST,
|v, overshoot| {
info!("{} {}", v, overshoot);
true
diff --git a/src/cap.rs b/src/cap.rs
index a6cb18a..a5be1ca 100644
--- a/src/cap.rs
+++ b/src/cap.rs
@@ -61,15 +61,17 @@ GPIO13
// Lower limit is necessary because we don't want to hit the threshold immediately
// on reading.
-const LOW_OVER: u32 = 1000;
-// Power of two for faster modulo
-const HIGH_OVER: u32 = LOW_OVER + 1023;
+// const LOW_OVER: u32 = 1000;
+// // Power of two for faster modulo
+// const HIGH_OVER: u32 = LOW_OVER + 1023;
+const LOW_OVER: u32 = 0;
+const HIGH_OVER: u32 = 0;
// Assume worst case from rp2040 datasheet.
// 3.3v vdd, 2v logical high voltage, 50kohm pullup, 0.01uF capacitor, 125Mhz clock.
// 0.5 * 50e3 * 0.01e-6 * 125e6 = 31250.0
// Then allow 50% leeway for tolerances.
-const MIN_CAPACITOR_DEL: u32 = 15000;
+const MIN_CAPACITOR_DEL: u32 = 0;
/// Extra iterations prior to taking output, so that `overshoot` is nice and noisy.
const WARMUP: usize = 16;
@@ -135,20 +137,30 @@ fn time_fall_unroll(pin_num: usize, syst: &mut SYST) -> Result<(u32, bool), ()>
// bank 0 single cycle IO in
let gpio_in = pac::SIO.gpio_in(0).ptr();
let mask = 1u32 << pin_num;
+
+ // let so = pac::SIO.gpio_out(0);
+ // let soe = pac::SIO.gpio_out(0);
+ // unsafe {
+ // so.value_set().write_value(1<<pin_num);
+ // soe.value_set().write_value(1<<pin_num);
+ // }
+ // cortex_m::asm::delay(10000);
+ // unsafe {
+ // soe.value_clr().write_value(1<<pin_num);
+ // }
+ // for testing with logic analyzer
+ // let mut out = Flex::new(unsafe { embassy_rp::peripherals::PIN_16::steal() });
+ // out.set_as_output();
+ // so.value_clr().write_value(1<<16);
+
let t = SyTi::new(syst);
+
let x0: u32;
let x1: u32;
let x2: u32;
let x3: u32;
let x4: u32;
let x5: u32;
-
- // for testing with logic analyzer
- // let so = pac::SIO.gpio_out(0);
- // let mut out = Flex::new(unsafe { embassy_rp::peripherals::PIN_16::steal() });
- // out.set_as_output();
- // so.value_clr().write_value(1<<16);
-
unsafe {
asm!(
// save
@@ -161,12 +173,13 @@ fn time_fall_unroll(pin_num: usize, syst: &mut SYST) -> Result<(u32, bool), ()>
"ldr {x2}, [{gpio_in}]",
"ldr {x3}, [{gpio_in}]",
"ldr {x4}, [{gpio_in}]",
- "ldr r7, [{gpio_in}]",
+ "ldr r7, [{gpio_in}]",
// only test the most recent sample. 1 cycle
"ands r7, {mask}",
// Loop if bit set, 2 cycles
"bne 222b",
+ // return last sample in x5
"mov {mask}, r7",
// restore
"mov r7, r10",
@@ -184,6 +197,7 @@ fn time_fall_unroll(pin_num: usize, syst: &mut SYST) -> Result<(u32, bool), ()>
}
let tick = t.done()?;
+
let pos = if x0 & mask == 0 {
0
} else if x1 & mask == 0 {
@@ -199,13 +213,15 @@ fn time_fall_unroll(pin_num: usize, syst: &mut SYST) -> Result<(u32, bool), ()>
} else {
6
};
+ let tick = tick + pos;
+ // let precise = pos != 0;
+ let precise = true;
- let precise = pos != 0;
- Ok((tick + pos, precise))
+ Ok((tick, precise))
}
// `f()` is called on each output `u32`.
-pub fn cap_rand<'d, P: Pin, F>(
+pub fn noise<'d, P: Pin, F>(
pin: &mut Flex<'d, P>,
pin_num: usize,
syst: &mut SYST,
@@ -270,11 +286,13 @@ where
// Pull down, time how long to reach threshold
pin.set_pull(Pull::Down);
+
// let t = SyTi::new(syst);
// while pin.is_high() {}
- // t.done()
- // time_fall(pin_num, syst)
+ // let r = t.done().map(|t| (t, true));
+
let r = time_fall_unroll(pin_num, syst);
+
pin.set_pull(Pull::None);
r
})?;
diff --git a/src/lib.rs b/src/lib.rs
index 44e5bfc..0a53d3a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,5 +7,5 @@ mod rng;
mod cap;
pub use rng::{setup, random};
-pub use cap::cap_rand;
+pub use cap::noise;
diff --git a/src/rng.rs b/src/rng.rs
index ba2a3e8..cc5377a 100644
--- a/src/rng.rs
+++ b/src/rng.rs
@@ -76,7 +76,7 @@ impl CapRng {
) -> Result<Self, getrandom::Error> {
let mut h = Sha256::new();
let mut count = 0;
- crate::cap::cap_rand(pin, pin_num, syst, |v, _over| {
+ crate::cap::noise(pin, pin_num, syst, |v, _over| {
h.update(v.to_be_bytes());
count += 1;
count < Self::SEED_SAMPLES
--
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