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Make header length calculation non generic #23

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Make header length calculation non generic #23

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166 changes: 86 additions & 80 deletions src/command.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,91 @@ enum ExtendedLen {
Forced,
}

/// Inner non-generic implementation
fn header_data(
command_extended_len: ExtendedLen,
command_data_len: usize,
command_le: ExpectedLen,
) -> BuildingHeaderData {
/// Returns (data, len of data, and is_extended)
fn serialize_data_len(
len: u16,
expected_len: ExpectedLen,
extended: ExtendedLen,
) -> (heapless::Vec<u8, 3>, bool) {
let expected_is_extended =
matches!(expected_len, ExpectedLen::Ne(257..) | ExpectedLen::Max);
match (len, expected_is_extended, extended) {
(0, _, _) => (Default::default(), false),
(1..=255, false, ExtendedLen::Unsupported | ExtendedLen::Supported) => {
([len as u8].as_slice().try_into().unwrap(), false)
}
_ => {
let l = len.to_be_bytes();
([0, l[0], l[1]].as_slice().try_into().unwrap(), true)
}
}
}

fn serialize_expected_len(
len: ExpectedLen,
lc_extended: bool,
data_is_empty: bool,
extended: ExtendedLen,
) -> heapless::Vec<u8, 3> {
match (len, lc_extended, data_is_empty, extended) {
(ExpectedLen::Ne(0), _, _, _) => Default::default(),
(
ExpectedLen::Ne(len @ 1..=255),
false,
_,
ExtendedLen::Unsupported | ExtendedLen::Supported,
) => [len as u8].as_slice().try_into().unwrap(),
(ExpectedLen::Ne(256), false, _, ExtendedLen::Unsupported | ExtendedLen::Supported) => {
[0].as_slice().try_into().unwrap()
}
(ExpectedLen::Ne(len), true, false, _) => {
let l = len.to_be_bytes();
[l[0], l[1]].as_slice().try_into().unwrap()
}
(ExpectedLen::Max, true, false, _) => [0, 0].as_slice().try_into().unwrap(),
(ExpectedLen::Ne(len), false, true, _) => {
let l = len.to_be_bytes();
[0, l[0], l[1]].as_slice().try_into().unwrap()
}
(ExpectedLen::Max, false, true, _) => [0, 0, 0].as_slice().try_into().unwrap(),
(ExpectedLen::Ne(257..) | ExpectedLen::Max, false, false, _)
| (_, false, false, ExtendedLen::Forced) => {
unreachable!("Can't have non extended Lc and extended Le")
}
(_, true, true, _) => {
unreachable!("Can't have both no data and data extended length")
}
}
}

let le = if command_extended_len == ExtendedLen::Unsupported {
command_le.min(256.into())
} else {
command_le
};

// Safe to unwrap because of check in `new`
let (data_len, lc_extended) = serialize_data_len(
command_data_len.try_into().unwrap(),
le,
command_extended_len,
);

let expected_data_len =
serialize_expected_len(le, lc_extended, command_data_len == 0, command_extended_len);
BuildingHeaderData {
le,
data_len,
expected_data_len,
}
}

#[derive(Debug, PartialEq, Eq, Clone)]
pub struct CommandBuilder<D> {
class: class::Class,
Expand Down Expand Up @@ -236,86 +321,7 @@ impl<D: DataSource> CommandBuilder<D> {
}

fn header_data(&self) -> BuildingHeaderData {
/// Returns (data, len of data, and is_extended)
fn serialize_data_len(
len: u16,
expected_len: ExpectedLen,
extended: ExtendedLen,
) -> (heapless::Vec<u8, 3>, bool) {
let expected_is_extended =
matches!(expected_len, ExpectedLen::Ne(257..) | ExpectedLen::Max);
match (len, expected_is_extended, extended) {
(0, _, _) => (Default::default(), false),
(1..=255, false, ExtendedLen::Unsupported | ExtendedLen::Supported) => {
([len as u8].as_slice().try_into().unwrap(), false)
}
_ => {
let l = len.to_be_bytes();
([0, l[0], l[1]].as_slice().try_into().unwrap(), true)
}
}
}

fn serialize_expected_len(
len: ExpectedLen,
lc_extended: bool,
data_is_empty: bool,
extended: ExtendedLen,
) -> heapless::Vec<u8, 3> {
match (len, lc_extended, data_is_empty, extended) {
(ExpectedLen::Ne(0), _, _, _) => Default::default(),
(
ExpectedLen::Ne(len @ 1..=255),
false,
_,
ExtendedLen::Unsupported | ExtendedLen::Supported,
) => [len as u8].as_slice().try_into().unwrap(),
(
ExpectedLen::Ne(256),
false,
_,
ExtendedLen::Unsupported | ExtendedLen::Supported,
) => [0].as_slice().try_into().unwrap(),
(ExpectedLen::Ne(len), true, false, _) => {
let l = len.to_be_bytes();
[l[0], l[1]].as_slice().try_into().unwrap()
}
(ExpectedLen::Max, true, false, _) => [0, 0].as_slice().try_into().unwrap(),
(ExpectedLen::Ne(len), false, true, _) => {
let l = len.to_be_bytes();
[0, l[0], l[1]].as_slice().try_into().unwrap()
}
(ExpectedLen::Max, false, true, _) => [0, 0, 0].as_slice().try_into().unwrap(),
(ExpectedLen::Ne(257..) | ExpectedLen::Max, false, false, _)
| (_, false, false, ExtendedLen::Forced) => {
unreachable!("Can't have non extended Lc and extended Le")
}
(_, true, true, _) => {
unreachable!("Can't have both no data and data extended length")
}
}
}

let le = if self.extended_length == ExtendedLen::Unsupported {
self.le.min(256.into())
} else {
self.le
};

// Safe to unwrap because of check in `new`
let (data_len, lc_extended) = serialize_data_len(
self.data.len().try_into().unwrap(),
le,
self.extended_length,
);

let expected_data_len =
serialize_expected_len(le, lc_extended, self.data.is_empty(), self.extended_length);
BuildingHeaderData {
le,
data_len,
expected_data_len,
}
header_data(self.extended_length, self.data.len(), self.le)
}

/// Required length for serialization in only one command.
Expand Down