mango-hal 0.2.1

Hardware Abstraction Layer for the mango operationg system.
Documentation 
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// SPDX-License-Identifier: MIT OR Apache-2.0
//
// Copyright (c) 2021-2023 Andre Richter <andre.o.richter@gmail.com>

//! Page allocation.

use super::MemoryRegion;
use crate::systems::rpi::{
  memory::{AddressType, Virtual},
  synchronization::IRQSafeNullLock,
};
use core::num::NonZeroUsize;
use mango_core::warn;

//--------------------------------------------------------------------------------------------------
// Public Definitions
//--------------------------------------------------------------------------------------------------

/// A page allocator that can be lazyily initialized.
pub struct PageAllocator<ATYPE: AddressType>
{
  pool: Option<MemoryRegion<ATYPE>>,
}

//--------------------------------------------------------------------------------------------------
// Global instances
//--------------------------------------------------------------------------------------------------

static KERNEL_MMIO_VA_ALLOCATOR: IRQSafeNullLock<PageAllocator<Virtual>> =
  IRQSafeNullLock::new(PageAllocator::new());

//--------------------------------------------------------------------------------------------------
// Public Code
//--------------------------------------------------------------------------------------------------

/// Return a reference to the kernel's MMIO virtual address allocator.
pub fn kernel_mmio_va_allocator() -> &'static IRQSafeNullLock<PageAllocator<Virtual>>
{
  &KERNEL_MMIO_VA_ALLOCATOR
}

impl<ATYPE: AddressType> PageAllocator<ATYPE>
{
  /// Create an instance.
  pub const fn new() -> Self
  {
    Self { pool: None }
  }

  /// Initialize the allocator.
  pub fn init(&mut self, pool: MemoryRegion<ATYPE>)
  {
    if self.pool.is_some()
    {
      warn!("Already initialized");
      return;
    }

    self.pool = Some(pool);
  }

  /// Allocate a number of pages.
  pub fn alloc(
    &mut self,
    num_requested_pages: NonZeroUsize,
  ) -> Result<MemoryRegion<ATYPE>, &'static str>
  {
    if self.pool.is_none()
    {
      return Err("Allocator not initialized");
    }

    self
      .pool
      .as_mut()
      .unwrap()
      .take_first_n_pages(num_requested_pages)
  }
}