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acpi_tables: aml: Avoid allocating temporary vector in AddressSpace

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Use extend_from_slice() vs creating a temporary vector.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This commit is contained in:
Rob Bradford 2021-11-03 15:08:15 +00:00
parent 99d4f77197
commit 6c181061df
1 changed files with 22 additions and 34 deletions
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56
acpi_tables/src/aml.rs
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@ -416,7 +416,7 @@ impl<T> AddressSpace<T> {
fn push_header(&self, bytes: &mut Vec<u8>, descriptor: u8, length: usize) {
bytes.push(descriptor); /* Word Address Space Descriptor */
bytes.append(&mut (length as u16).to_le_bytes().to_vec());
bytes.extend_from_slice(&(length as u16).to_le_bytes());
bytes.push(self.r#type as u8); /* type */
let generic_flags = 1 << 2 /* Min Fixed */ | 1 << 3; /* Max Fixed */
bytes.push(generic_flags);
@ -425,65 +425,53 @@ impl<T> AddressSpace<T> {
}
impl Aml for AddressSpace<u16> {
fn to_aml_bytes(&self) -> Vec<u8> {
let mut bytes = Vec::new();
fn append_aml_bytes(&self, bytes: &mut Vec<u8>) {
self.push_header(
&mut bytes,
bytes,
0x88, /* Word Address Space Descriptor */
3 + 5 * std::mem::size_of::<u16>(), /* 3 bytes of header + 5 u16 fields */
);
bytes.append(&mut 0u16.to_le_bytes().to_vec()); /* Granularity */
bytes.append(&mut self.min.to_le_bytes().to_vec()); /* Min */
bytes.append(&mut self.max.to_le_bytes().to_vec()); /* Max */
bytes.append(&mut 0u16.to_le_bytes().to_vec()); /* Translation */
bytes.extend_from_slice(&0u16.to_le_bytes()); /* Granularity */
bytes.extend_from_slice(&self.min.to_le_bytes()); /* Min */
bytes.extend_from_slice(&self.max.to_le_bytes()); /* Max */
bytes.extend_from_slice(&0u16.to_le_bytes()); /* Translation */
let len = self.max - self.min + 1;
bytes.append(&mut len.to_le_bytes().to_vec()); /* Length */
bytes
bytes.extend_from_slice(&len.to_le_bytes()); /* Length */
}
}
impl Aml for AddressSpace<u32> {
fn to_aml_bytes(&self) -> Vec<u8> {
let mut bytes = Vec::new();
fn append_aml_bytes(&self, bytes: &mut Vec<u8>) {
self.push_header(
&mut bytes,
bytes,
0x87, /* DWord Address Space Descriptor */
3 + 5 * std::mem::size_of::<u32>(), /* 3 bytes of header + 5 u32 fields */
);
bytes.append(&mut 0u32.to_le_bytes().to_vec()); /* Granularity */
bytes.append(&mut self.min.to_le_bytes().to_vec()); /* Min */
bytes.append(&mut self.max.to_le_bytes().to_vec()); /* Max */
bytes.append(&mut 0u32.to_le_bytes().to_vec()); /* Translation */
bytes.extend_from_slice(&0u32.to_le_bytes()); /* Granularity */
bytes.extend_from_slice(&self.min.to_le_bytes()); /* Min */
bytes.extend_from_slice(&self.max.to_le_bytes()); /* Max */
bytes.extend_from_slice(&0u32.to_le_bytes()); /* Translation */
let len = self.max - self.min + 1;
bytes.append(&mut len.to_le_bytes().to_vec()); /* Length */
bytes
bytes.extend_from_slice(&len.to_le_bytes()); /* Length */
}
}
impl Aml for AddressSpace<u64> {
fn to_aml_bytes(&self) -> Vec<u8> {
let mut bytes = Vec::new();
fn append_aml_bytes(&self, bytes: &mut Vec<u8>) {
self.push_header(
&mut bytes,
bytes,
0x8A, /* QWord Address Space Descriptor */
3 + 5 * std::mem::size_of::<u64>(), /* 3 bytes of header + 5 u64 fields */
);
bytes.append(&mut 0u64.to_le_bytes().to_vec()); /* Granularity */
bytes.append(&mut self.min.to_le_bytes().to_vec()); /* Min */
bytes.append(&mut self.max.to_le_bytes().to_vec()); /* Max */
bytes.append(&mut 0u64.to_le_bytes().to_vec()); /* Translation */
bytes.extend_from_slice(&0u64.to_le_bytes()); /* Granularity */
bytes.extend_from_slice(&self.min.to_le_bytes()); /* Min */
bytes.extend_from_slice(&self.max.to_le_bytes()); /* Max */
bytes.extend_from_slice(&0u64.to_le_bytes()); /* Translation */
let len = self.max - self.min + 1;
bytes.append(&mut len.to_le_bytes().to_vec()); /* Length */
bytes
bytes.extend_from_slice(&len.to_le_bytes()); /* Length */
}
}