gba_save 0.3.0

Tools for interacting with backup media on Game Boy Advance cartridges.
Documentation 
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pub(crate) const WAITCNT: *mut WaitstateControl = 0x0400_0204 as *mut WaitstateControl;
/// Interrupt Master Enable.
///
/// This register allows enabling and disabling interrupts.
pub(crate) const IME: *mut bool = 0x0400_0208 as *mut bool;
pub(crate) const DMA3_SOURCE: *mut *const u16 = 0x0400_00D4 as *mut *const u16;
pub(crate) const DMA3_DESTINATION: *mut *mut u16 = 0x0400_00D8 as *mut *mut u16;
pub(crate) const DMA3_LEN: *mut u16 = 0x0400_00DC as *mut u16;
pub(crate) const DMA3_CNT: *mut DmaControl = 0x0400_00DE as *mut DmaControl;

#[derive(Debug)]
#[repr(u8)]
pub(crate) enum Cycles {
    _4 = 0,
    _3 = 1,
    _2 = 2,
    _8 = 3,
}

#[derive(Debug)]
pub(crate) struct WaitstateControl(u16);

impl WaitstateControl {
    pub(crate) fn set_backup_waitstate(&mut self, cycles: Cycles) {
        self.0 &= 0b1111_1111_1111_1100;
        self.0 |= cycles as u16;
    }

    pub(crate) fn set_eeprom_waitstate(&mut self, cycles: Cycles) {
        self.0 &= 0b1111_1100_1111_1111;
        self.0 |= (cycles as u16) << 8;
    }
}

/// Direct memory access control.
///
/// Used for interacting with EEPROM.
#[derive(Debug)]
pub(crate) struct DmaControl(u16);

impl DmaControl {
    pub(crate) const fn new() -> Self {
        Self(0)
    }

    pub(crate) const fn enable(mut self) -> Self {
        self.0 |= 0b1000_0000_0000_0000;
        self
    }

    pub(crate) const fn enabled(self) -> bool {
        self.0 & 0b1000_0000_0000_0000 != 0
    }
}

#[cfg(test)]
mod tests {
    use super::{Cycles, WaitstateControl};
    use gba_test::test;

    #[test]
    fn set_backup_waitstate_4() {
        let mut waitstate = WaitstateControl(0);
        waitstate.set_backup_waitstate(Cycles::_4);

        assert_eq!(waitstate.0, 0);
    }

    #[test]
    fn set_backup_waitstate_3() {
        let mut waitstate = WaitstateControl(0);
        waitstate.set_backup_waitstate(Cycles::_3);

        assert_eq!(waitstate.0, 1);
    }

    #[test]
    fn set_backup_waitstate_2() {
        let mut waitstate = WaitstateControl(0);
        waitstate.set_backup_waitstate(Cycles::_2);

        assert_eq!(waitstate.0, 2);
    }

    #[test]
    fn set_backup_waitstate_8() {
        let mut waitstate = WaitstateControl(0);
        waitstate.set_backup_waitstate(Cycles::_8);

        assert_eq!(waitstate.0, 3);
    }

    #[test]
    fn set_backup_waitstate_with_preexisting_value() {
        let mut waitstate = WaitstateControl(3);
        waitstate.set_backup_waitstate(Cycles::_4);

        assert_eq!(waitstate.0, 0);
    }

    #[test]
    fn set_eeprom_waitstate_4() {
        let mut waitstate = WaitstateControl(0);
        waitstate.set_eeprom_waitstate(Cycles::_4);

        assert_eq!(waitstate.0, 0);
    }

    #[test]
    fn set_eeprom_waitstate_3() {
        let mut waitstate = WaitstateControl(0);
        waitstate.set_eeprom_waitstate(Cycles::_3);

        assert_eq!(waitstate.0, 0x100);
    }

    #[test]
    fn set_eeprom_waitstate_2() {
        let mut waitstate = WaitstateControl(0);
        waitstate.set_eeprom_waitstate(Cycles::_2);

        assert_eq!(waitstate.0, 0x200);
    }

    #[test]
    fn set_eeprom_waitstate_8() {
        let mut waitstate = WaitstateControl(0);
        waitstate.set_eeprom_waitstate(Cycles::_8);

        assert_eq!(waitstate.0, 0x300);
    }

    #[test]
    fn set_eeprom_waitstate_with_preexisting_value() {
        let mut waitstate = WaitstateControl(0xffff);
        waitstate.set_eeprom_waitstate(Cycles::_4);

        assert_eq!(waitstate.0, 0xfcff);
    }
}