From cb87b864dd39c722e67aa1852a48cca44740aa74 Mon Sep 17 00:00:00 2001
From: Matt Johnston <matt@ucc.asn.au>
Date: Wed, 5 Oct 2022 00:05:07 +0800
Subject: [PATCH] tidy asm
---
src/cap.rs | 37 +++++++++++--------------------------
1 file changed, 11 insertions(+), 26 deletions(-)
diff --git a/src/cap.rs b/src/cap.rs
index 0110556..9df7830 100644
--- a/src/cap.rs
+++ b/src/cap.rs
@@ -136,41 +136,36 @@ fn time_fall_unroll(pin_num: usize, syst: &mut SYST) -> Result<(u32, bool), ()>
let gpio_in = pac::SIO.gpio_in(0).ptr();
let mask = 1u32 << pin_num;
let t = SyTi::new(syst);
- let dbg: u32;
let x0: u32;
let x1: u32;
let x2: u32;
let x3: u32;
let x4: u32;
- let x5: u32;
- let x6: u32;
- let x7: u32;
- let dbg: 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_high();
// out.set_as_output();
+ // so.value_clr().write_value(1<<16);
unsafe {
asm!(
- "222:",
+ // save
"mov r10, r7",
- // read gpio_in register, 1 cycle
+
+ "222:",
+ // read gpio_in register, 5 cycles
"ldr {x0}, [{gpio_in}]",
"ldr {x1}, [{gpio_in}]",
"ldr {x2}, [{gpio_in}]",
"ldr {x3}, [{gpio_in}]",
"ldr {x4}, [{gpio_in}]",
- "ldr {x4}, [{gpio_in}]",
-
- // Only test the most recent sample. there's a slight chance
- // of missing a glitchy short trigger in an earlier sample,
- // but we'll catch up later if we miss it.
+ // only test the most recent sample. 1 cycle
"ands {x4}, {mask}",
// Loop if bit set, 2 cycles
"bne 222b",
+
+ // restore
"mov r7, r10",
mask = in(reg) mask,
@@ -186,15 +181,6 @@ fn time_fall_unroll(pin_num: usize, syst: &mut SYST) -> Result<(u32, bool), ()>
}
let tick = t.done()?;
- // unsafe {
- // so.value_clr().write_value(1<<16);
- // so.value_set().write_value(1<<16);
- // so.value_clr().write_value(1<<16);
- // // out.set_low();
- // // out.set_high();
- // // out.set_low();
- // }
-
let pos = if x0 & mask == 0 {
0
} else if x1 & mask == 0 {
@@ -209,9 +195,8 @@ fn time_fall_unroll(pin_num: usize, syst: &mut SYST) -> Result<(u32, bool), ()>
5
};
- // TODO: pos=0 output should be discarded
- // debug!("{} {} {} {} pos {}", x0, x1, x2, x3, pos);
- Ok((tick + pos, pos != 0))
+ let precise = pos != 0;
+ Ok((tick + pos, precise))
}
// `f()` is called on each output `u32`.
--
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