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Added a section about determining size metrics of a rp2040 binary

master
Weird Constructor 1 year ago
parent
commit
8ac3c474aa
  1. 4
      pwm_dac_saw_sampling/src/main.rs
  2. 61
      resources.md

4
pwm_dac_saw_sampling/src/main.rs

@ -72,10 +72,6 @@ fn main() -> ! {
// >> fc 40.0 0.000000100
// > 39788.735772971224
use alloc;
let x : Vec<f32> = alloc::vec::Vec::new();
x.push(0.2);
let sin =
unsafe {
core::mem::transmute::<_, fn(f32) -> f32>

61
resources.md

@ -35,6 +35,67 @@ A broad overview of the rp2040 Rust ecosystem:
- [Cortex-M allocator](https://crates.io/crates/alloc-cortex-m)
Use with care, and "it's probably safer to reserve heap space with linker scripts!"
## Reading material
- [The Embedded Rust Book](https://doc.rust-lang.org/beta/embedded-book/intro/index.html)
## Determining rp2040 Rust Program Size on Flash and RAM
The easiest overview you can achieve with the `size` tool that comes
with Linux:
```
./target/thumbv6m-none-eabi/release$ size rp2040-pwm-dac-sine-saw-synth
text data bss dec hex filename
12176 48 1032 13256 33c8 rp2040-pwm-dac-sine-saw-synth
```
- `text` is the program code, which resides in flash.
- `data` is the static data of your program, which will end up in flash _and_ RAM.
- `bss` is uninitialized data, which will consume RAM.
You can also install binutils for cargo:
```
cargo install cargo-binutils
# also this, or otherwise you will get a "No such file or directory"
# error when using `cargo nm`:
rustup component add llvm-tools-preview
```
And then run `cargo nm`:
```
./rp2040_code/pwm_dac_saw_sampling$ cargo nm --release | sort
00000000 N {"package":"defmt","tag":"defmt_prim","data":"{=__internal_Display}","disambiguator":"14725451269531928465"}
...
10000000 r rp2040_pwm_dac_sine_saw_synth::BOOT2::h4551b8283fee8692
10002fe0 D __veneer_limit
2003fbc8 A _stack_start
...
20040000 B __sheap
```
The addresses starting with a `100*` are in flash, and the addresses
starting with `200*` are in RAM.
If you want to know the size of the individual elements, you can use
this command (which I found via `cargo nm -h`):
```
./p2040_code/pwm_dac_saw_sampling$ cargo nm --release -- --print-size --size-sort
100013f6 00000000 T ADC_IRQ_FIFO
...
100001f0 0000000a T main
...
100001fc 00000848 t rp2040_pwm_dac_sine_saw_synth::__cortex_m_rt_main::hff61f1c9c409d1f1
```
The second column is the size of the given symbols. As you can see, the
main function which contains the most code is also the biggest.
The numbers are in hexadecimal, so `0x848` are actually `2120 bytes`.
## Raspberry Pi Pico Pinout
![Raspberry Pi Pico Pinout](res/raspberry_pi_pico_pinout_overview.png)

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