use libcortex_a9::mmu::{AccessPermissions, L1_PAGE_SIZE, L1Table};

/// Symbols defined by the linker script
extern "C" {
    static __text_start: usize;
    static __text_end: usize;
    static __rodata_start: usize;
    static __rodata_end: usize;
}

/// Apply basic memory protection to the regions defined by the linker
/// script for the runtime on core 0.
///
/// Therefore these regions need to be aligned to 1 MB.
pub fn setup_core0() {
    let text_start = unsafe { &__text_start as *const _ as usize };
    let text_end = unsafe { &__text_end as *const _ as usize };
    let rodata_start = unsafe { &__rodata_start as *const _ as usize };
    let rodata_end = unsafe { &__rodata_end as *const _ as usize };

    let l1table = L1Table::get();
    for addr in (0..0xFFFF_FFFF).step_by(L1_PAGE_SIZE) {
        l1table.update(addr as *const usize, |l1section| {
            if addr >= text_start && addr < text_end {
                // Code: R-X
                l1section.access = AccessPermissions::ReadOnly;
                l1section.exec = true;
            } else if addr >= rodata_start && addr < rodata_end {
                // Data: R--
                l1section.access = AccessPermissions::ReadOnly;
                l1section.exec = false;
            } else {
                // Everything else: RW-
                l1section.access = AccessPermissions::FullAccess;
                l1section.exec = false;
            }
        });
    }
}

pub fn setup_core1(kernel_data: &[u8]) {
    let kernel_start = (&kernel_data[0] as *const _ as usize) & !(L1_PAGE_SIZE - 1);
    let kernel_end = ((&kernel_data[kernel_data.len() - 1] as *const _ as usize) | (L1_PAGE_SIZE - 1)) + 1;
    let text_start = unsafe { &__text_start as *const _ as usize };
    let text_end = unsafe { &__text_end as *const _ as usize };
    let rodata_start = unsafe { &__rodata_start as *const _ as usize };
    let rodata_end = unsafe { &__rodata_end as *const _ as usize };

    let l1table = L1Table::get();
    for addr in (0..0xFFFF_FFFF).step_by(L1_PAGE_SIZE) {
        l1table.update(addr as *const usize, |l1section| {
            if addr >= kernel_start && addr < kernel_end {
                // Kernel code/data: RWX
                l1section.access = AccessPermissions::FullAccess;
                l1section.exec = true;
            } else if addr >= text_start && addr < text_end {
                // Runtime code: R-X
                l1section.access = AccessPermissions::ReadOnly;
                l1section.exec = true;
            } else if addr >= rodata_start && addr < rodata_end {
                // Data: R--
                l1section.access = AccessPermissions::ReadOnly;
                l1section.exec = false;
            } else {
                // Everything else: RW-
                l1section.access = AccessPermissions::FullAccess;
                l1section.exec = false;
            }
        });
    }
}