2021-10-11 17:58:09 +00:00
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pub enum BitIndex {
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I0,
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I1,
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I2,
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I3,
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I4,
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I5,
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I6,
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I7,
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}
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pub fn get_bit_index(index: BitIndex) -> u8 {
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match index {
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BitIndex::I0 => 0,
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BitIndex::I1 => 1,
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BitIndex::I2 => 2,
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BitIndex::I3 => 3,
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BitIndex::I4 => 4,
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BitIndex::I5 => 5,
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BitIndex::I6 => 6,
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BitIndex::I7 => 7,
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}
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}
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pub fn get_bit(byte: u8, index: BitIndex) -> bool {
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((byte >> get_bit_index(index)) & 0b00000001) == 1
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}
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pub fn set_bit(byte: u8, value: bool, index: BitIndex) -> u8 {
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match value {
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true => 0b00000001 << get_bit_index(index) | byte,
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false => ((0b0000001 << get_bit_index(index)) ^ 0b11111111) & byte,
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}
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}
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2021-10-14 01:50:48 +00:00
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pub fn join_bytes(byte1: u8, byte2: u8) -> u16 {
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((byte1 as u16) << 8) | (byte2 as u16)
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}
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2021-10-15 04:32:48 +00:00
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pub fn add_half_carry(byte1: u8, byte2: u8) -> bool {
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let byte1 = byte1 & 0b00001111;
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let byte2 = byte2 & 0b00001111;
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get_bit(byte1 + byte2, BitIndex::I4)
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}
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pub fn sub_half_carry(byte1: u8, byte2: u8) -> bool {
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let byte1 = byte1 & 0b00001111;
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let byte2 = byte2 & 0b00001111;
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byte2 > byte1
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}
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2021-10-11 17:58:09 +00:00
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_set_bit() {
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assert_eq!(set_bit(0b00000000, true, BitIndex::I0), 0b00000001);
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assert_eq!(set_bit(0b00000000, true, BitIndex::I1), 0b00000010);
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assert_eq!(set_bit(0b00000000, true, BitIndex::I2), 0b00000100);
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assert_eq!(set_bit(0b00000000, true, BitIndex::I3), 0b00001000);
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assert_eq!(set_bit(0b00000000, true, BitIndex::I4), 0b00010000);
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assert_eq!(set_bit(0b00000000, true, BitIndex::I5), 0b00100000);
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assert_eq!(set_bit(0b00000000, true, BitIndex::I6), 0b01000000);
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assert_eq!(set_bit(0b00000000, true, BitIndex::I7), 0b10000000);
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assert_eq!(set_bit(0b11111111, false, BitIndex::I0), 0b11111110);
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assert_eq!(set_bit(0b11111111, false, BitIndex::I1), 0b11111101);
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assert_eq!(set_bit(0b11111111, false, BitIndex::I2), 0b11111011);
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assert_eq!(set_bit(0b11111111, false, BitIndex::I3), 0b11110111);
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assert_eq!(set_bit(0b11111111, false, BitIndex::I4), 0b11101111);
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assert_eq!(set_bit(0b11111111, false, BitIndex::I5), 0b11011111);
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assert_eq!(set_bit(0b11111111, false, BitIndex::I6), 0b10111111);
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assert_eq!(set_bit(0b11111111, false, BitIndex::I7), 0b01111111);
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// Just a couple of random test
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assert_eq!(set_bit(0b00000001, true, BitIndex::I0), 0b00000001);
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assert_eq!(set_bit(0b11101111, true, BitIndex::I4), 0b11111111);
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assert_eq!(set_bit(0b11111110, false, BitIndex::I0), 0b11111110);
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assert_eq!(set_bit(0b00010000, false, BitIndex::I4), 0b00000000);
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}
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#[test]
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fn test_get_bit() {
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assert_eq!(get_bit(0b00000001, BitIndex::I0), true);
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assert_eq!(get_bit(0b00000010, BitIndex::I1), true);
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assert_eq!(get_bit(0b00000100, BitIndex::I2), true);
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assert_eq!(get_bit(0b00001000, BitIndex::I3), true);
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assert_eq!(get_bit(0b00010000, BitIndex::I4), true);
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assert_eq!(get_bit(0b00100000, BitIndex::I5), true);
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assert_eq!(get_bit(0b01000000, BitIndex::I6), true);
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assert_eq!(get_bit(0b10000000, BitIndex::I7), true);
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assert_eq!(get_bit(0b11111110, BitIndex::I0), false);
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assert_eq!(get_bit(0b11111101, BitIndex::I1), false);
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assert_eq!(get_bit(0b11111011, BitIndex::I2), false);
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assert_eq!(get_bit(0b11110111, BitIndex::I3), false);
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assert_eq!(get_bit(0b11101111, BitIndex::I4), false);
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assert_eq!(get_bit(0b11011111, BitIndex::I5), false);
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assert_eq!(get_bit(0b10111111, BitIndex::I6), false);
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assert_eq!(get_bit(0b01111111, BitIndex::I7), false);
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}
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2021-10-14 01:50:48 +00:00
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#[test]
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fn test_join_two_bytes() {
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assert_eq!(join_bytes(0b10101010, 0b11111111), 0b1010101011111111);
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assert_eq!(join_bytes(0b11111111, 0b10101010), 0b1111111110101010);
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}
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2021-10-15 04:32:48 +00:00
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#[test]
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fn test_half_carry() {
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assert_eq!(add_half_carry(0b10101010, 0b11111111), true);
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assert_eq!(add_half_carry(0b00000100, 0b00001100), true);
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assert_eq!(add_half_carry(0b00000100, 0b00000100), false);
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assert_eq!(add_half_carry(0b00000100, 0b00001000), false);
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2021-10-15 04:58:51 +00:00
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assert_eq!(add_half_carry(0b00001111, 0b00000001), true);
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2021-10-15 04:32:48 +00:00
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assert_eq!(sub_half_carry(0b00010000, 0b00001000), true);
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assert_eq!(sub_half_carry(0b00000000, 0b00000001), true);
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assert_eq!(sub_half_carry(0b00001000, 0b00001000), false);
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}
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2021-10-11 17:58:09 +00:00
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}
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