#pragma once
// vim: ft=cpp

/// \file memory.h
/// Import memory layout constants necessary for boot

#include <stddef.h>
#include <stdint.h>

#include <arch/memory.h>

namespace bootproto {
    struct args;
}

/// Allocate from the default allocator.
/// \arg size  The size in bytes requested
/// \returns   A pointer to the newly allocated memory,
///            or nullptr on error
void * kalloc(size_t size);

/// Free memory allocated by `kalloc`.
/// \arg p  Pointer that was returned from a `kalloc` call
void kfree(void *p);

/// Kernel space virtual memory layout
namespace mem {

using arch::frame_size;
using arch::kernel_offset;

/// Max number of pages for a kernel stack
constexpr unsigned kernel_stack_pages = 2;

/// Max number of pages for a kernel buffer
constexpr unsigned kernel_buffer_pages = 16;

/*[[[cog code generation
from os.path import join
from memory import Layout

layout = Layout(join(definitions_path, "memory_layout.yaml"))
l = max([len(r.name) for r in layout.regions])

for region in layout.regions:
    cog.outl(f"constexpr size_t {region.name:>{l}}_size = {region.size:#14x};")

cog.outl("")

for region in layout.regions:
    cog.outl(f"constexpr uintptr_t {region.name:>{l}}_offset = {region.start:#x};")

]]]*/
///[[[end]]]

/// Helper to determine if a physical address can be accessed
/// through the linear_offset area.
constexpr bool linear_mappable(uintptr_t a) { return (a & linear_offset) == 0; }

/// Get the number of pages needed to hold `bytes` bytes
inline constexpr size_t bytes_to_pages(size_t bytes) {
    return ((bytes - 1) / frame_size) + 1;
}

/// Convert a physical address to a virtual one (in the linear-mapped area)
template <typename T> T * to_virtual(uintptr_t a) {
    return reinterpret_cast<T*>(a|linear_offset);
}

/// Convert a physical address to a virtual one (in the linear-mapped area)
template <typename T> T * to_virtual(T *p) {
    return to_virtual<T>(reinterpret_cast<uintptr_t>(p));
}

/// Get the number of pages needed for a given number of bytes.
/// \arg bytes  The number of bytes desired
/// \returns    The number of pages needed to contain the desired bytes
constexpr size_t page_count(size_t bytes) { return ((bytes - 1) >> 12) + 1; }

/// Get the given address, aligned to the next lowest page
constexpr uintptr_t page_align_down(uintptr_t a) { return a & ~(frame_size-1); }

/// Get the given address, aligned to the next page
constexpr uintptr_t page_align_up(uintptr_t a) { return page_align_down(a-1) + frame_size; }

/// Initialize memory. Create the kernel vm space and its memory regions,
/// the physical page allocator and heap allocator, and run global constructors.
void initialize(bootproto::args &args);

} // namespace mem