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Optimize Option<Flash>::from(FlashValue) using bitwise AND #2843

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Optimize Option<Flash>::from(FlashValue) using bitwise AND #2843

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127 changes: 27 additions & 100 deletions crates/media-metadata/src/exif/flash/data.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -57,112 +57,39 @@ impl From<u32> for FlashMode {
}

impl From<FlashValue> for Option<Flash> {
// TODO(brxken128): This can be heavily optimized with bitwise AND
// e.g. to see if flash was fired, `(value & 1) != 0`
// or to see if red eye reduction was enabled, `(value & 64) != 0`
// May not be worth it as some states may be invalid according to `https://www.awaresystems.be/imaging/tiff/tifftags/privateifd/exif/flash.html`
fn from(value: FlashValue) -> Self {
#[allow(clippy::as_conversions)]
let mut data = Flash {
mode: FlashMode::from(value as u32),
..Default::default()
let numeric_value = value as u32;

// Bit 0 indicates if flash fired
let fired = (numeric_value & 0x01) != 0;

// Bits 1-2 indicate return state
let returned = match numeric_value & 0x06 {
0x06 => Some(true), // Returned
0x02 => Some(false), // No return
_ => None, // No data
};

#[allow(clippy::match_same_arms)]
match value {
FlashValue::Fired => {
data.fired = Some(true);
}
FlashValue::NoFire => {
data.fired = Some(false);
}
FlashValue::FiredReturn => {
data.fired = Some(true);
data.returned = Some(true);
}
FlashValue::FiredNoReturn => {
data.fired = Some(true);
data.returned = Some(false);
}
FlashValue::AutoFired => {
data.fired = Some(true);
}
FlashValue::AutoFiredNoReturn => {
data.fired = Some(true);
data.returned = Some(false);
}
FlashValue::OffNoFire => data.fired = Some(false),
FlashValue::AutoNoFire => data.fired = Some(false),
FlashValue::NoFlashFunction | FlashValue::OffNoFlashFunction | FlashValue::Unknown => {
data = Flash::default();
}
FlashValue::AutoFiredRedEyeReduction => {
data.fired = Some(true);
data.red_eye_reduction = Some(true);
}
FlashValue::AutoFiredRedEyeReductionNoReturn => {
data.fired = Some(true);
data.red_eye_reduction = Some(true);
data.returned = Some(false);
}
FlashValue::AutoFiredRedEyeReductionReturn => {
data.fired = Some(true);
data.red_eye_reduction = Some(true);
data.returned = Some(true);
}
FlashValue::OnFired => {
data.fired = Some(true);
}
FlashValue::OnNoFire => {
data.fired = Some(false);
}
FlashValue::AutoFiredReturn => {
data.fired = Some(true);
data.returned = Some(true);
}
FlashValue::OnReturn => {
data.returned = Some(true);
}
FlashValue::OnNoReturn => data.returned = Some(false),
FlashValue::AutoNoFireRedEyeReduction => {
data.fired = Some(false);
data.red_eye_reduction = Some(true);
}
FlashValue::OffNoFireNoReturn => {
data.fired = Some(false);
data.returned = Some(false);
}
FlashValue::OffRedEyeReduction => data.red_eye_reduction = Some(true),
FlashValue::OnRedEyeReduction => data.red_eye_reduction = Some(true),
FlashValue::FiredRedEyeReductionNoReturn => {
data.fired = Some(true);
data.red_eye_reduction = Some(true);
data.returned = Some(false);
}
FlashValue::FiredRedEyeReduction => {
data.fired = Some(true);
data.red_eye_reduction = Some(true);
}
FlashValue::FiredRedEyeReductionReturn => {
data.fired = Some(true);
data.red_eye_reduction = Some(true);
data.returned = Some(false);
}
FlashValue::OnRedEyeReductionReturn => {
data.red_eye_reduction = Some(true);
data.returned = Some(true);
}
FlashValue::OnRedEyeReductionNoReturn => {
data.red_eye_reduction = Some(true);
data.returned = Some(false);
}
}
// Bit 6 indicates red-eye reduction
let red_eye_reduction = if (numeric_value & 0x40) != 0 {
Some(true)
} else {
None
};

let mode = FlashMode::from(numeric_value);

let flash = Flash {
mode,
fired: Some(fired),
returned,
red_eye_reduction,
};

// this means it had a value of Flash::NoFlashFunctionality
if data == Flash::default() {
if flash == Flash::default() {
None
} else {
Some(data)
Some(flash)
}
}
}
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