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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,71 @@ | ||
| /* | ||
| * srx: The fast Symbol Ranking based compressor. | ||
| * Copyright (C) 2023 Mai Thanh Minh (a.k.a. thanhminhmr) | ||
| * | ||
| * This program is free software: you can redistribute it and/or modify it under | ||
| * the terms of the GNU General Public License as published by the Free Software | ||
| * Foundation, either version 3 of the License, or (at your option) any later | ||
| * version. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, but WITHOUT | ||
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | ||
| * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more | ||
| * details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License along with | ||
| * this program. If not, see <https://www.gnu.org/licenses/>. | ||
| */ | ||
|
|
||
| use crate::primary_context::matched::ByteMatched; | ||
| use crate::primary_context::history::ByteHistory; | ||
|
|
||
| // ----------------------------------------------- | ||
|
|
||
| pub struct PrimaryContext<const SIZE: usize> { | ||
| last_byte: u8, | ||
| hash_value: usize, | ||
| contexts: Box<[ByteHistory; SIZE]>, | ||
| } | ||
|
|
||
| impl<const SIZE: usize> PrimaryContext<SIZE> { | ||
| // assert that SIZE is power of 2 | ||
| const _SIZE_CHECK: () = assert!(SIZE != 0 && (SIZE & (SIZE - 1)) == 0); | ||
|
|
||
| pub fn new() -> Self { | ||
| Self { | ||
| last_byte: 0, | ||
| hash_value: 0, | ||
| contexts: Box::new([ByteHistory::new(); SIZE]), | ||
| } | ||
| } | ||
|
|
||
| pub fn get(&self) -> (u8, u8, u8, u8, usize, usize) { | ||
| let (first_byte, second_byte, third_byte, count): (u8, u8, u8, usize) = | ||
| self.contexts[self.hash_value].get(); | ||
| return ( | ||
| self.last_byte, | ||
| first_byte, | ||
| second_byte, | ||
| third_byte, | ||
| count, | ||
| self.hash_value, | ||
| ); | ||
| } | ||
|
|
||
| fn update(&mut self, next_byte: u8) { | ||
| self.last_byte = next_byte; | ||
| self.hash_value = (self.hash_value * (5 << 5) + next_byte as usize + 1) % SIZE; | ||
| debug_assert!(self.hash_value < SIZE); | ||
| } | ||
|
|
||
| pub fn matching(&mut self, next_byte: u8) -> ByteMatched { | ||
| let matching_byte: ByteMatched = self.contexts[self.hash_value].matching(next_byte); | ||
| self.update(next_byte); | ||
| return matching_byte; | ||
| } | ||
|
|
||
| pub fn matched(&mut self, next_byte: u8, matched: ByteMatched) { | ||
| self.contexts[self.hash_value].matched(next_byte, matched); | ||
| self.update(next_byte); | ||
| } | ||
| } |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,99 @@ | ||
| /* | ||
| * srx: The fast Symbol Ranking based compressor. | ||
| * Copyright (C) 2023 Mai Thanh Minh (a.k.a. thanhminhmr) | ||
| * | ||
| * This program is free software: you can redistribute it and/or modify it under | ||
| * the terms of the GNU General Public License as published by the Free Software | ||
| * Foundation, either version 3 of the License, or (at your option) any later | ||
| * version. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, but WITHOUT | ||
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS | ||
| * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more | ||
| * details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License along with | ||
| * this program. If not, see <https://www.gnu.org/licenses/>. | ||
| */ | ||
|
|
||
| use crate::primary_context::matched::ByteMatched; | ||
|
|
||
| // ----------------------------------------------- | ||
|
|
||
| #[derive(Clone, Copy)] | ||
| pub struct ByteHistory(u32); | ||
|
|
||
| impl ByteHistory { | ||
| pub fn new() -> Self { | ||
| Self(0) | ||
| } | ||
|
|
||
| pub fn get(&self) -> (u8, u8, u8, usize) { | ||
| ( | ||
| self.0 as u8, // first byte | ||
| (self.0 >> 8) as u8, // second byte | ||
| (self.0 >> 16) as u8, // third byte | ||
| (self.0 >> 24) as usize, // count TODO would a state machine here be better? | ||
| ) | ||
| } | ||
|
|
||
| pub fn matching(&mut self, next_byte: u8) -> ByteMatched { | ||
| let mask: u32 = self.0 ^ (0x10101 * next_byte as u32); | ||
| return if (mask & 0x0000FF) == 0 { | ||
| // mask for the first byte | ||
| // increase count by 1, capped at 255 | ||
| self.0 += if self.0 < 0xFF000000 { 0x01000000 } else { 0 }; | ||
|
|
||
| ByteMatched::FIRST | ||
| } else if (mask & 0x00FF00) == 0 { | ||
| // mask for the second byte | ||
| self.0 = (self.0 & 0xFF0000) // keep the third byte | ||
| | ((self.0 << 8) & 0xFF00) // bring the old first byte to second place | ||
| | next_byte as u32 // set the first byte | ||
| | 0x1000000; // set count to 1 | ||
|
|
||
| ByteMatched::SECOND | ||
| } else if (mask & 0xFF0000) == 0 { | ||
| // mask for the third byte | ||
| self.0 = ((self.0 << 8) & 0xFFFF00) // move old first/second to second/third | ||
| | next_byte as u32 // set the first byte | ||
| | 0x1000000; // set count to 1 | ||
|
|
||
| ByteMatched::THIRD | ||
| } else { | ||
| // not match | ||
| self.0 = ((self.0 << 8) & 0xFFFF00) // move old first/second to second/third | ||
| | next_byte as u32; // set the first byte | ||
|
|
||
| ByteMatched::NONE | ||
| }; | ||
| } | ||
|
|
||
| pub fn matched(&mut self, next_byte: u8, matched: ByteMatched) { | ||
| match matched { | ||
| ByteMatched::FIRST => { | ||
| // first byte | ||
| // increase count by 1, capped at 255 | ||
| self.0 += if self.0 < 0xFF000000 { 0x01000000 } else { 0 }; | ||
| } | ||
| ByteMatched::SECOND => { | ||
| // second byte | ||
| self.0 = (self.0 & 0xFF0000) // keep the third byte | ||
| | ((self.0 << 8) & 0xFF00) // bring the old first byte to second place | ||
| | next_byte as u32 // set the first byte | ||
| | 0x1000000; // set count to 1 | ||
| } | ||
| ByteMatched::THIRD => { | ||
| // third byte | ||
| self.0 = ((self.0 << 8) & 0xFFFF00) // move old first/second to second/third | ||
| | next_byte as u32 // set the first byte | ||
| | 0x1000000; // set count to 1 | ||
| } | ||
| ByteMatched::NONE => { | ||
| // not match | ||
| self.0 = ((self.0 << 8) & 0xFFFF00) // move old first/second to second/third | ||
| | next_byte as u32; // set the first byte | ||
| } | ||
| } | ||
| } | ||
| } |
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