/*
 * Copyright (c) 2026, Chloe M.
 * Provided under the BSD-3 clause.
 *
 * Description: Physical memory management
 * Author:      Chloe M.
 */

#include <mm/pm.h>
#include <ke/bpal.h>
#include <ex/trace.h>

#define DTRACE(Fmt, ...) \
    TRACE("[ PM ]: " Fmt, ##__VA_ARGS__)

/* Safe macro to get region string */
#define PM_REGION(TYPE)                 \
    ((TYPE) >= NELEM(PmRegionTable))    \
        ? "bad type"                    \
        : PmRegionTable[(TYPE)]

/*
 * Table of known memory regions
 */
static const CHAR *PmRegionTable[] = {
    [MEMORY_USABLE]         = "available",
    [MEMORY_RESERVED]       = "reserved",
    [MEMORY_ACPI_RECLAIM]   = "acpi reclaimable",
    [MEMORY_ACPI_NVS]       = "acpi nv-sleep",
    [MEMORY_BAD]            = "bad",
    [MEMORY_BOOTLOADER]     = "bootloader",
    [MEMORY_KERNEL]         = "system",
    [MEMORY_FRAMEBUFFER]    = "vram",
    [MEMORY_ACPI_TABLES]    = "acpi tables"
};

/*
 * Probe physical memory for usable regions and list
 * installed memory.
 */
static VOID
PmProbe(VOID)
{
    PT_STATUS Status;
    BPAL_HANDLE BpalHandle;
    MEMMAP_ENTRY Entry;
    UPTR Start, End;
    USIZE Index;

    /*
     * We obtain memory map entries from the BPAL layer as it is provided
     * by the bootloader which got it from firmware.
     */
    KeBpalGetHandle(&BpalHandle);

    /* Iterate each memory entry */
    for (Index = 0;; ++Index) {
        Status = BpalHandle.MemEntryIdx(Index, &Entry);

        /* Are we out of entries to fetch? */
        if (PT_ERROR(Status)) {
            break;
        }

        Start = Entry.Base;
        End = Start + Entry.Length;
        DTRACE(
            "%p - %p : %s\n",
            Start,
            End,
            PM_REGION(Entry.Type)
        );
    }
}

VOID
MmPmInit(VOID)
{
    DTRACE("probing physical memory...\n");
    PmProbe();
}