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//! URL percent decode operation as an IR composition.
/// CPU-independent IR kernel for URL percent-encoded byte escapes.
pub mod kernel {
use super::super::shared::{and, hex_nibble, BYTE_BOUNDED_LAWS};
use crate::ir::{BufferDecl, DataType, Expr, Node, Program};
use crate::ops::{OpSpec, BYTES_TO_BYTES_INPUTS, BYTES_TO_BYTES_OUTPUTS};
/// GPU region decoder for URL percent-encoded byte escapes.
#[derive(Debug, Clone, Copy, Default)]
pub struct UrlDecode;
impl UrlDecode {
/// Declarative operation specification.
pub const SPEC: OpSpec = OpSpec::composition(
"decode.url",
BYTES_TO_BYTES_INPUTS,
BYTES_TO_BYTES_OUTPUTS,
BYTE_BOUNDED_LAWS,
Self::program,
);
/// Build the canonical IR program.
#[must_use]
pub fn program() -> Program {
let idx = Expr::var("idx");
let byte = Expr::load("input", idx.clone());
let percent = Expr::eq(byte.clone(), Expr::u32(u32::from(b'%')));
let plus = Expr::eq(byte.clone(), Expr::u32(u32::from(b'+')));
Program::new(
vec![
BufferDecl::read("input", 0, DataType::Bytes),
BufferDecl::output("out", 1, DataType::Bytes),
],
[64, 1, 1],
vec![
Node::let_bind("idx", Expr::gid_x()),
Node::if_then(
and(
Expr::lt(idx.clone(), Expr::buf_len("input")),
Expr::lt(idx.clone(), Expr::buf_len("out")),
),
vec![Node::store(
"out",
idx.clone(),
Expr::select(
and(
percent,
Expr::lt(
Expr::add(idx.clone(), Expr::u32(2)),
Expr::buf_len("input"),
),
),
decoded_escape(idx.clone()),
Expr::select(plus, Expr::u32(u32::from(b' ')), byte),
),
)],
),
],
)
}
}
/// Decode the `%NN` escape beginning at `idx`.
#[must_use]
pub fn decoded_escape(idx: Expr) -> Expr {
let hi = hex_nibble(Expr::load("input", Expr::add(idx.clone(), Expr::u32(1))));
let lo = hex_nibble(Expr::load("input", Expr::add(idx, Expr::u32(2))));
Expr::bitor(Expr::shl(hi, Expr::u32(4)), lo)
}
}
pub use kernel::UrlDecode;