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use base::{Base, mask, enc, dec};
use tool::{div_ceil, chunk_unchecked, chunk_mut_unchecked};
fn encode_block<B: Base>(base: &B, input: &[u8], output: &mut [u8]) {
let mut x = 0u64;
for j in 0 .. input.len() {
x |= (input[j] as u64) << 8 * (enc(base) - 1 - j);
}
for j in 0 .. output.len() {
let y = (x >> base.bit() * (dec(base) - 1 - j)) as u8;
output[j] = base.sym(y & mask(base));
}
}
fn encode_last<B: Base>(base: &B, input: &[u8], output: &mut [u8]) {
let ilen = input.len();
let olen = div_ceil(8 * ilen, base.bit());
encode_block(base, input, &mut output[0 .. olen]);
for j in olen .. output.len() {
output[j] = base.pad();
}
}
pub fn encode_len<B: Base>(base: &B, len: usize) -> usize {
div_ceil(len, enc(base)) * dec(base)
}
pub fn encode_nopad_len<B: Base>(base: &B, len: usize) -> usize {
div_ceil(8 * len, base.bit())
}
pub fn encode_mut<B: Base>(base: &B, input: &[u8], output: &mut [u8]) {
let enc = enc(base);
let dec = dec(base);
let ilen = input.len();
let olen = encode_len(base, ilen);
assert_eq!(output.len(), olen);
let n = ilen / enc;
for i in 0 .. n {
let input = unsafe { chunk_unchecked(input, enc, i) };
let output = unsafe { chunk_mut_unchecked(output, dec, i) };
encode_block(base, input, output);
}
encode_last(base, &input[enc * n ..], &mut output[dec * n ..]);
}
pub fn encode_nopad_mut<B: Base>(base: &B, input: &[u8], output: &mut [u8]) {
let enc = enc(base);
let dec = dec(base);
let ilen = input.len();
let olen = encode_nopad_len(base, ilen);
assert_eq!(output.len(), olen);
let n = ilen / enc;
for i in 0 .. n {
let input = unsafe { chunk_unchecked(input, enc, i) };
let output = unsafe { chunk_mut_unchecked(output, dec, i) };
encode_block(base, input, output);
}
encode_block(base, &input[enc * n ..], &mut output[dec * n ..]);
}
pub fn encode<B: Base>(base: &B, input: &[u8]) -> String {
let mut output = vec![0u8; encode_len(base, input.len())];
encode_mut(base, input, &mut output);
unsafe {
String::from_utf8_unchecked(output)
}
}
pub fn encode_nopad<B: Base>(base: &B, input: &[u8]) -> String {
let mut output = vec![0u8; encode_nopad_len(base, input.len())];
encode_nopad_mut(base, input, &mut output);
unsafe {
String::from_utf8_unchecked(output)
}
}