76 lines
1.6 KiB
Rust
76 lines
1.6 KiB
Rust
use crate::processor::Direction;
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use std::mem::transmute;
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pub(crate) fn as_signed(unsigned: u8) -> i8 {
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unsafe { transmute(unsigned) }
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}
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pub(crate) fn get_bit(byte: u8, flag: u8) -> bool {
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let mask = 1 << flag;
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let got = byte & mask;
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got > 0x0
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}
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pub(crate) fn set_or_clear_bit(byte: u8, flag: u8, condition: bool) -> u8 {
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if condition {
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set_bit(byte, flag)
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} else {
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clear_bit(byte, flag)
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}
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}
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pub(crate) fn set_bit(byte: u8, flag: u8) -> u8 {
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byte | (1 << flag)
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}
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pub(crate) fn clear_bit(byte: u8, flag: u8) -> u8 {
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byte & (!(1 << flag))
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}
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pub(crate) fn rotate(byte: u8, direction: &Direction) -> (u8, bool) {
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match direction {
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Direction::Left => {
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let carry = get_bit(byte, 7);
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let r = byte << 1;
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(r, carry)
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}
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Direction::Right => {
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let carry = get_bit(byte, 0);
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let r = byte >> 1;
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(r, carry)
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}
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}
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}
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pub(crate) fn get_rotation_carry(direction: &Direction) -> u8 {
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match direction {
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Direction::Left => 0b1,
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Direction::Right => 0b10000000,
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}
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}
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pub trait Nibbles {
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fn get_low_nibble(&self) -> u8;
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fn get_high_nibble(&self) -> u8;
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fn set_low_nibble(&mut self, val: u8);
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fn set_high_nibble(&mut self, val: u8);
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}
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impl Nibbles for u8 {
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fn get_low_nibble(&self) -> u8 {
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*self & 0x0F
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}
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fn get_high_nibble(&self) -> u8 {
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(*self >> 4) & 0x0F
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}
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fn set_low_nibble(&mut self, val: u8) {
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*self = (*self & 0xF0) | (val & 0x0F);
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}
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fn set_high_nibble(&mut self, val: u8) {
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*self = (*self & 0x0F) | (val << 4);
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}
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}
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