feat: add display UI with splash screen, dashboard, and RSSI sparkline

Implement full SSD1306 OLED display support:
- Splash screen on boot (1.5s) with project name, version, board
- Dashboard showing radio state, config, counters, RSSI/SNR
- RSSI history sparkline (64-sample ring buffer, 2px-wide bars)
- DisplayOn/DisplayOff host commands routed via dedicated channel
- Pure render functions against generic DrawTarget (no hardware coupling)
- Display on/off control bypasses radio task entirely

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/litrs/src/float/mod.rs

@@ -0,0 +1,257 @@
+use std::{fmt, str::FromStr};
+
+use crate::{
+    err::{perr, ParseErrorKind::*},
+    parse::{check_suffix, end_dec_digits, first_byte_or_empty},
+    Buffer, ParseError,
+};
+
+
+
+/// A floating point literal, e.g. `3.14`, `8.`, `135e12`, or `1.956e2f64`.
+///
+/// This kind of literal has several forms, but generally consists of a main
+/// number part, an optional exponent and an optional type suffix. See
+/// [the reference][ref] for more information.
+///
+/// A leading minus sign `-` is not part of the literal grammar! `-3.14` are two
+/// tokens in the Rust grammar. Further, `27` and `27f32` are both not float,
+/// but integer literals! Consequently `FloatLit::parse` will reject them.
+///
+///
+/// [ref]: https://doc.rust-lang.org/reference/tokens.html#floating-point-literals
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct FloatLit<B: Buffer> {
+    /// The whole raw input. The `usize` fields in this struct partition this
+    /// string. Always true: `end_integer_part <= end_fractional_part`.
+    ///
+    /// ```text
+    ///    12_3.4_56e789f32
+    ///        ╷    ╷   ╷
+    ///        |    |   └ end_number_part = 13
+    ///        |    └ end_fractional_part = 9
+    ///        └ end_integer_part = 4
+    ///
+    ///    246.
+    ///       ╷╷
+    ///       |└ end_fractional_part = end_number_part = 4
+    ///       └ end_integer_part = 3
+    ///
+    ///    1234e89
+    ///        ╷  ╷
+    ///        |  └ end_number_part = 7
+    ///        └ end_integer_part = end_fractional_part = 4
+    /// ```
+    raw: B,
+
+    /// The first index not part of the integer part anymore. Since the integer
+    /// part is at the start, this is also the length of that part.
+    end_integer_part: usize,
+
+    /// The first index after the fractional part.
+    end_fractional_part: usize,
+
+    /// The first index after the whole number part (everything except type suffix).
+    end_number_part: usize,
+}
+
+impl<B: Buffer> FloatLit<B> {
+    /// Parses the input as a floating point literal. Returns an error if the
+    /// input is invalid or represents a different kind of literal. Will also
+    /// reject decimal integer literals like `23` or `17f32`, in accordance
+    /// with the spec.
+    pub fn parse(s: B) -> Result<Self, ParseError> {
+        match first_byte_or_empty(&s)? {
+            b'0'..=b'9' => {
+                // TODO: simplify once RFC 2528 is stabilized
+                let FloatLit {
+                    end_integer_part,
+                    end_fractional_part,
+                    end_number_part,
+                    ..
+                } = parse_impl(&s)?;
+
+                Ok(Self { raw: s, end_integer_part, end_fractional_part, end_number_part })
+            }
+            _ => Err(perr(0, DoesNotStartWithDigit)),
+        }
+    }
+
+    /// Returns the number part (including integer part, fractional part and
+    /// exponent), but without the suffix. If you want an actual floating
+    /// point value, you need to parse this string, e.g. with `f32::from_str`
+    /// or an external crate.
+    pub fn number_part(&self) -> &str {
+        &(*self.raw)[..self.end_number_part]
+    }
+
+    /// Returns the non-empty integer part of this literal.
+    pub fn integer_part(&self) -> &str {
+        &(*self.raw)[..self.end_integer_part]
+    }
+
+    /// Returns the optional fractional part of this literal. Does not include
+    /// the period. If a period exists in the input, `Some` is returned, `None`
+    /// otherwise. Note that `Some("")` might be returned, e.g. for `3.`.
+    pub fn fractional_part(&self) -> Option<&str> {
+        if self.end_integer_part == self.end_fractional_part {
+            None
+        } else {
+            Some(&(*self.raw)[self.end_integer_part + 1..self.end_fractional_part])
+        }
+    }
+
+    /// Optional exponent part. Might be empty if there was no exponent part in
+    /// the input. Includes the `e` or `E` at the beginning.
+    pub fn exponent_part(&self) -> &str {
+        &(*self.raw)[self.end_fractional_part..self.end_number_part]
+    }
+
+    /// The optional suffix. Returns `""` if the suffix is empty/does not exist.
+    pub fn suffix(&self) -> &str {
+        &(*self.raw)[self.end_number_part..]
+    }
+
+    /// Returns the raw input that was passed to `parse`.
+    pub fn raw_input(&self) -> &str {
+        &self.raw
+    }
+
+    /// Returns the raw input that was passed to `parse`, potentially owned.
+    pub fn into_raw_input(self) -> B {
+        self.raw
+    }
+}
+
+impl FloatLit<&str> {
+    /// Makes a copy of the underlying buffer and returns the owned version of
+    /// `Self`.
+    pub fn to_owned(&self) -> FloatLit<String> {
+        FloatLit {
+            raw: self.raw.to_owned(),
+            end_integer_part: self.end_integer_part,
+            end_fractional_part: self.end_fractional_part,
+            end_number_part: self.end_number_part,
+        }
+    }
+}
+
+impl<B: Buffer> fmt::Display for FloatLit<B> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", &*self.raw)
+    }
+}
+
+/// Precondition: first byte of string has to be in `b'0'..=b'9'`.
+#[inline(never)]
+pub(crate) fn parse_impl(input: &str) -> Result<FloatLit<&str>, ParseError> {
+    // Integer part.
+    let end_integer_part = end_dec_digits(input.as_bytes());
+    let rest = &input[end_integer_part..];
+
+
+    // Fractional part.
+    let end_fractional_part = if rest.as_bytes().get(0) == Some(&b'.') {
+        // The fractional part must not start with `_`.
+        if rest.as_bytes().get(1) == Some(&b'_') {
+            return Err(perr(end_integer_part + 1, UnexpectedChar));
+        }
+
+        end_dec_digits(rest[1..].as_bytes()) + 1 + end_integer_part
+    } else {
+        end_integer_part
+    };
+    let rest = &input[end_fractional_part..];
+
+    // If we have a period that is not followed by decimal digits, the
+    // literal must end now.
+    if end_integer_part + 1 == end_fractional_part && !rest.is_empty() {
+        return Err(perr(end_integer_part + 1, UnexpectedChar));
+    }
+
+    // Optional exponent.
+    let end_number_part = if rest.starts_with('e') || rest.starts_with('E') {
+        // Strip single - or + sign at the beginning.
+        let exp_number_start = match rest.as_bytes().get(1) {
+            Some(b'-') | Some(b'+') => 2,
+            _ => 1,
+        };
+
+        // Find end of exponent and make sure there is at least one digit.
+        let end_exponent = end_dec_digits(rest[exp_number_start..].as_bytes()) + exp_number_start;
+        if !rest[exp_number_start..end_exponent].bytes().any(|b| matches!(b, b'0'..=b'9')) {
+            return Err(perr(
+                end_fractional_part..end_fractional_part + end_exponent,
+                NoExponentDigits,
+            ));
+        }
+
+        end_exponent + end_fractional_part
+    } else {
+        end_fractional_part
+    };
+
+    // Make sure the suffix is valid.
+    let suffix = &input[end_number_part..];
+    check_suffix(suffix).map_err(|kind| perr(end_number_part..input.len(), kind))?;
+
+    // A float literal needs either a fractional or exponent part, otherwise its
+    // an integer literal.
+    if end_integer_part == end_number_part {
+        return Err(perr(None, UnexpectedIntegerLit));
+    }
+
+    Ok(FloatLit {
+        raw: input,
+        end_integer_part,
+        end_fractional_part,
+        end_number_part,
+    })
+}
+
+
+/// All possible float type suffixes.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[non_exhaustive]
+pub enum FloatType {
+    F32,
+    F64,
+}
+
+impl FloatType {
+    /// Returns the type corresponding to the given suffix (e.g. `"f32"` is
+    /// mapped to `Self::F32`). If the suffix is not a valid float type, `None`
+    /// is returned.
+    pub fn from_suffix(suffix: &str) -> Option<Self> {
+        match suffix {
+            "f32" => Some(FloatType::F32),
+            "f64" => Some(FloatType::F64),
+            _ => None,
+        }
+    }
+
+    /// Returns the suffix for this type, e.g. `"f32"` for `Self::F32`.
+    pub fn suffix(self) -> &'static str {
+        match self {
+            Self::F32 => "f32",
+            Self::F64 => "f64",
+        }
+    }
+}
+
+impl FromStr for FloatType {
+    type Err = ();
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Self::from_suffix(s).ok_or(())
+    }
+}
+
+impl fmt::Display for FloatType {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.suffix().fmt(f)
+    }
+}
+
+
+#[cfg(test)]
+mod tests;

vendor/litrs/src/float/tests.rs

@@ -0,0 +1,253 @@
+use super::{FloatLit, FloatType};
+use crate::{
+    test_util::{assert_parse_ok_eq, assert_roundtrip},
+    Literal, ParseError,
+};
+
+
+// ===== Utility functions =======================================================================
+
+/// Helper macro to check parsing a float.
+///
+/// This macro contains quite a bit of logic itself (which can be buggy of
+/// course), so we have a few test functions below to test a bunch of cases
+/// manually.
+macro_rules! check {
+    ($intpart:literal $fracpart:literal $exppart:literal $suffix:tt) => {
+        let input = concat!($intpart, $fracpart, $exppart, check!(@stringify_suffix $suffix));
+        let expected_float = FloatLit {
+            raw: input,
+            end_integer_part: $intpart.len(),
+            end_fractional_part: $intpart.len() + $fracpart.len(),
+            end_number_part: $intpart.len() + $fracpart.len() + $exppart.len(),
+        };
+
+        assert_parse_ok_eq(
+            input, FloatLit::parse(input), expected_float.clone(), "FloatLit::parse");
+        assert_parse_ok_eq(
+            input, Literal::parse(input), Literal::Float(expected_float), "Literal::parse");
+        assert_eq!(FloatLit::parse(input).unwrap().suffix(), check!(@ty $suffix));
+        assert_roundtrip(expected_float.to_owned(), input);
+    };
+    (@ty f32) => { "f32" };
+    (@ty f64) => { "f64" };
+    (@ty -) => { "" };
+    (@stringify_suffix -) => { "" };
+    (@stringify_suffix $suffix:ident) => { stringify!($suffix) };
+}
+
+
+// ===== Actual tests ===========================================================================
+
+#[test]
+fn manual_without_suffix() -> Result<(), ParseError> {
+    let f = FloatLit::parse("3.14")?;
+    assert_eq!(f.number_part(), "3.14");
+    assert_eq!(f.integer_part(), "3");
+    assert_eq!(f.fractional_part(), Some("14"));
+    assert_eq!(f.exponent_part(), "");
+    assert_eq!(f.suffix(), "");
+
+    let f = FloatLit::parse("9.")?;
+    assert_eq!(f.number_part(), "9.");
+    assert_eq!(f.integer_part(), "9");
+    assert_eq!(f.fractional_part(), Some(""));
+    assert_eq!(f.exponent_part(), "");
+    assert_eq!(f.suffix(), "");
+
+    let f = FloatLit::parse("8e1")?;
+    assert_eq!(f.number_part(), "8e1");
+    assert_eq!(f.integer_part(), "8");
+    assert_eq!(f.fractional_part(), None);
+    assert_eq!(f.exponent_part(), "e1");
+    assert_eq!(f.suffix(), "");
+
+    let f = FloatLit::parse("8E3")?;
+    assert_eq!(f.number_part(), "8E3");
+    assert_eq!(f.integer_part(), "8");
+    assert_eq!(f.fractional_part(), None);
+    assert_eq!(f.exponent_part(), "E3");
+    assert_eq!(f.suffix(), "");
+
+    let f = FloatLit::parse("8_7_6.1_23e15")?;
+    assert_eq!(f.number_part(), "8_7_6.1_23e15");
+    assert_eq!(f.integer_part(), "8_7_6");
+    assert_eq!(f.fractional_part(), Some("1_23"));
+    assert_eq!(f.exponent_part(), "e15");
+    assert_eq!(f.suffix(), "");
+
+    let f = FloatLit::parse("8.2e-_04_9")?;
+    assert_eq!(f.number_part(), "8.2e-_04_9");
+    assert_eq!(f.integer_part(), "8");
+    assert_eq!(f.fractional_part(), Some("2"));
+    assert_eq!(f.exponent_part(), "e-_04_9");
+    assert_eq!(f.suffix(), "");
+
+    Ok(())
+}
+
+#[test]
+fn manual_with_suffix() -> Result<(), ParseError> {
+    let f = FloatLit::parse("3.14f32")?;
+    assert_eq!(f.number_part(), "3.14");
+    assert_eq!(f.integer_part(), "3");
+    assert_eq!(f.fractional_part(), Some("14"));
+    assert_eq!(f.exponent_part(), "");
+    assert_eq!(FloatType::from_suffix(f.suffix()), Some(FloatType::F32));
+
+    let f = FloatLit::parse("8e1f64")?;
+    assert_eq!(f.number_part(), "8e1");
+    assert_eq!(f.integer_part(), "8");
+    assert_eq!(f.fractional_part(), None);
+    assert_eq!(f.exponent_part(), "e1");
+    assert_eq!(FloatType::from_suffix(f.suffix()), Some(FloatType::F64));
+
+    let f = FloatLit::parse("8_7_6.1_23e15f32")?;
+    assert_eq!(f.number_part(), "8_7_6.1_23e15");
+    assert_eq!(f.integer_part(), "8_7_6");
+    assert_eq!(f.fractional_part(), Some("1_23"));
+    assert_eq!(f.exponent_part(), "e15");
+    assert_eq!(FloatType::from_suffix(f.suffix()), Some(FloatType::F32));
+
+    let f = FloatLit::parse("8.2e-_04_9f64")?;
+    assert_eq!(f.number_part(), "8.2e-_04_9");
+    assert_eq!(f.integer_part(), "8");
+    assert_eq!(f.fractional_part(), Some("2"));
+    assert_eq!(f.exponent_part(), "e-_04_9");
+    assert_eq!(FloatType::from_suffix(f.suffix()), Some(FloatType::F64));
+
+    Ok(())
+}
+
+#[test]
+fn simple() {
+    check!("3" ".14" "" -);
+    check!("3" ".14" "" f32);
+    check!("3" ".14" "" f64);
+
+    check!("3" "" "e987654321" -);
+    check!("3" "" "e987654321" f64);
+
+    check!("42_888" ".05" "" -);
+    check!("42_888" ".05" "E5___" f32);
+    check!("123456789" "" "e_1" f64);
+    check!("123456789" ".99" "e_1" f64);
+    check!("123456789" ".99" "" f64);
+    check!("123456789" ".99" "" -);
+
+    check!("147" ".3_33" "" -);
+    check!("147" ".3_33__" "E3" f64);
+    check!("147" ".3_33__" "" f32);
+
+    check!("147" ".333" "e-10" -);
+    check!("147" ".333" "e-_7" f32);
+    check!("147" ".333" "e+10" -);
+    check!("147" ".333" "e+_7" f32);
+
+    check!("86" "." "" -);
+    check!("0" "." "" -);
+    check!("0_" "." "" -);
+    check!("0" ".0000001" "" -);
+    check!("0" ".000_0001" "" -);
+
+    check!("0" ".0" "e+0" -);
+    check!("0" "" "E+0" -);
+    check!("34" "" "e+0" -);
+    check!("0" ".9182" "E+0" f32);
+}
+
+#[test]
+fn non_standard_suffixes() {
+    #[track_caller]
+    fn check_suffix(
+        input: &str,
+        integer_part: &str,
+        fractional_part: Option<&str>,
+        exponent_part: &str,
+        suffix: &str,
+    ) {
+        let lit = FloatLit::parse(input)
+            .unwrap_or_else(|e| panic!("expected to parse '{}' but got {}", input, e));
+        assert_eq!(lit.integer_part(), integer_part);
+        assert_eq!(lit.fractional_part(), fractional_part);
+        assert_eq!(lit.exponent_part(), exponent_part);
+        assert_eq!(lit.suffix(), suffix);
+
+        let lit = match Literal::parse(input) {
+            Ok(Literal::Float(f)) => f,
+            other => panic!("Expected float literal, but got {other:?} for '{input}'"),
+        };
+        assert_eq!(lit.integer_part(), integer_part);
+        assert_eq!(lit.fractional_part(), fractional_part);
+        assert_eq!(lit.exponent_part(), exponent_part);
+        assert_eq!(lit.suffix(), suffix);
+    }
+
+    check_suffix("7.1f23", "7", Some("1"), "", "f23");
+    check_suffix("7.1f320", "7", Some("1"), "", "f320");
+    check_suffix("7.1f64_", "7", Some("1"), "", "f64_");
+    check_suffix("8.1f649", "8", Some("1"), "", "f649");
+    check_suffix("8.1f64f32", "8", Some("1"), "", "f64f32");
+    check_suffix("23e2_banana", "23", None, "e2_", "banana");
+    check_suffix("23.2_banana", "23", Some("2_"), "", "banana");
+    check_suffix("23e2pe55ter", "23", None, "e2", "pe55ter");
+    check_suffix("23e2p_e55ter", "23", None, "e2", "p_e55ter");
+    check_suffix("3.15Jürgen", "3", Some("15"), "", "Jürgen");
+    check_suffix("3e2e5", "3", None, "e2", "e5");
+    check_suffix("3e2e5f", "3", None, "e2", "e5f");
+}
+
+#[test]
+fn parse_err() {
+    assert_err!(FloatLit, "", Empty, None);
+    assert_err_single!(FloatLit::parse("."), DoesNotStartWithDigit, 0);
+    assert_err_single!(FloatLit::parse("+"), DoesNotStartWithDigit, 0);
+    assert_err_single!(FloatLit::parse("-"), DoesNotStartWithDigit, 0);
+    assert_err_single!(FloatLit::parse("e"), DoesNotStartWithDigit, 0);
+    assert_err_single!(FloatLit::parse("e8"), DoesNotStartWithDigit, 0);
+    assert_err!(FloatLit, "0e", NoExponentDigits, 1..2);
+    assert_err_single!(FloatLit::parse("f32"), DoesNotStartWithDigit, 0);
+    assert_err_single!(FloatLit::parse("foo"), DoesNotStartWithDigit, 0);
+
+    assert_err_single!(FloatLit::parse("inf"), DoesNotStartWithDigit, 0);
+    assert_err_single!(FloatLit::parse("nan"), DoesNotStartWithDigit, 0);
+    assert_err_single!(FloatLit::parse("NaN"), DoesNotStartWithDigit, 0);
+    assert_err_single!(FloatLit::parse("NAN"), DoesNotStartWithDigit, 0);
+
+    assert_err_single!(FloatLit::parse("_2.7"), DoesNotStartWithDigit, 0);
+    assert_err_single!(FloatLit::parse(".5"), DoesNotStartWithDigit, 0);
+    assert_err!(FloatLit, "1e", NoExponentDigits, 1..2);
+    assert_err!(FloatLit, "1.e4", UnexpectedChar, 2);
+    assert_err!(FloatLit, "3._4", UnexpectedChar, 2);
+    assert_err!(FloatLit, "3.f32", UnexpectedChar, 2);
+    assert_err!(FloatLit, "3.e5", UnexpectedChar, 2);
+    assert_err!(FloatLit, "12345._987", UnexpectedChar, 6);
+    assert_err!(FloatLit, "46._", UnexpectedChar, 3);
+    assert_err!(FloatLit, "46.f32", UnexpectedChar, 3);
+    assert_err!(FloatLit, "46.e3", UnexpectedChar, 3);
+    assert_err!(FloatLit, "46._e3", UnexpectedChar, 3);
+    assert_err!(FloatLit, "46.e3f64", UnexpectedChar, 3);
+    assert_err!(FloatLit, "23.4e_", NoExponentDigits, 4..6);
+    assert_err!(FloatLit, "23E___f32", NoExponentDigits, 2..6);
+    assert_err!(FloatLit, "55e3.1", UnexpectedChar, 4..6);
+
+    assert_err!(FloatLit, "3.7+", UnexpectedChar, 3..4);
+    assert_err!(FloatLit, "3.7+2", UnexpectedChar, 3..5);
+    assert_err!(FloatLit, "3.7-", UnexpectedChar, 3..4);
+    assert_err!(FloatLit, "3.7-2", UnexpectedChar, 3..5);
+    assert_err!(FloatLit, "3.7e+", NoExponentDigits, 3..5);
+    assert_err!(FloatLit, "3.7e-", NoExponentDigits, 3..5);
+    assert_err!(FloatLit, "3.7e-+3", NoExponentDigits, 3..5); // suboptimal error
+    assert_err!(FloatLit, "3.7e+-3", NoExponentDigits, 3..5); // suboptimal error
+    assert_err_single!(FloatLit::parse("0x44.5"), InvalidSuffix, 1..6);
+
+    assert_err_single!(FloatLit::parse("3"), UnexpectedIntegerLit, None);
+    assert_err_single!(FloatLit::parse("35_389"), UnexpectedIntegerLit, None);
+    assert_err_single!(FloatLit::parse("9_8_7f32"), UnexpectedIntegerLit, None);
+    assert_err_single!(FloatLit::parse("9_8_7banana"), UnexpectedIntegerLit, None);
+    assert_err_single!(FloatLit::parse("7f23"), UnexpectedIntegerLit, None);
+    assert_err_single!(FloatLit::parse("7f320"), UnexpectedIntegerLit, None);
+    assert_err_single!(FloatLit::parse("7f64_"), UnexpectedIntegerLit, None);
+    assert_err_single!(FloatLit::parse("8f649"), UnexpectedIntegerLit, None);
+    assert_err_single!(FloatLit::parse("8f64f32"), UnexpectedIntegerLit, None);
+}