agb 0.13.0

//! A module containing low-level assembly functions that can be loaded into
//! WRAM. Both flash media and battery-backed SRAM require reads to be
//! performed via code in WRAM and cannot be accessed by DMA.

extern "C" {
    fn agb_rs__WramTransferBuf(src: *const u8, dst: *mut u8, count: usize);
    fn agb_rs__WramReadByte(src: *const u8) -> u8;
    fn agb_rs__WramVerifyBuf(buf1: *const u8, buf2: *const u8, count: usize) -> bool;
}

/// Copies data from a given memory address into a buffer.
///
/// This should be used to access any data found in flash or battery-backed
/// SRAM, as you must read those one byte at a time and from code stored
/// in WRAM.
///
/// This uses raw addresses into the memory space. Use with care.
#[inline(always)]
pub unsafe fn read_raw_buf(dst: &mut [u8], src: usize) {
    if !dst.is_empty() {
        agb_rs__WramTransferBuf(src as _, dst.as_mut_ptr(), dst.len());
    }
}

/// Copies data from a buffer into a given memory address.
///
/// This is not strictly needed to write into save media, but reuses the
/// optimized loop used in `read_raw_buf`, and will often be faster.
///
/// This uses raw addresses into the memory space. Use with care.
#[inline(always)]
pub unsafe fn write_raw_buf(dst: usize, src: &[u8]) {
    if !src.is_empty() {
        agb_rs__WramTransferBuf(src.as_ptr(), dst as _, src.len());
    }
}

/// Verifies that the data in a buffer matches that in a given memory address.
///
/// This should be used to access any data found in flash or battery-backed
/// SRAM, as you must read those one byte at a time and from code stored
/// in WRAM.
///
/// This uses raw addresses into the memory space. Use with care.
#[inline(always)]
pub unsafe fn verify_raw_buf(buf1: &[u8], buf2: usize) -> bool {
    if !buf1.is_empty() {
        agb_rs__WramVerifyBuf(buf1.as_ptr(), buf2 as _, buf1.len() - 1)
    } else {
        true
    }
}

/// Reads a byte from a given memory address.
///
/// This should be used to access any data found in flash or battery-backed
/// SRAM, as you must read those from code found in WRAM.
///
/// This uses raw addresses into the memory space. Use with care.
#[inline(always)]
pub unsafe fn read_raw_byte(src: usize) -> u8 {
    agb_rs__WramReadByte(src as _)
}