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

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

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

/* Use to convert type constants to strings */
#define MEM_TYPE(TYPE)          \
    ((TYPE) < NELEM(TypeTab))   \
        ? TypeTab[(TYPE)]       \
        : "invalid"

/*
 * Memory type constant to human readable
 * string table.
 */
static const char *TypeTab[] = {
    [MEMORY_USABLE]         = "usable",
    [MEMORY_RESERVED]       = "reserved",
    [MEMORY_ACPI_RECLAIM]   = "acpi reclaimable",
    [MEMORY_ACPI_NVS]       = "acpi nvs",
    [MEMORY_BAD]            = "bad*",
    [MEMORY_BOOTLOADER]     = "bootloader",
    [MEMORY_KERNEL]         = "stoskrnl.sys",
    [MEMORY_FRAMEBUFFER]    = "framebuffer",
    [MEMORY_ACPI_TABLES]    = "acpi tables"
};

/* Globals */
static USIZE UsableMemory = 0;

/*
 * Print the units of a size in a pretty format
 *
 * @Length: Number of bytes
 * @Title:  Title of units
 */
static inline VOID
MmPrintUnits(USIZE Length, const CHAR *Title)
{
    if (Title == NULL) {
        return;
    }

    if (Length >= UNIT_GIB) {
        DTRACE("%d gib %s\n", Length / UNIT_GIB, Title);
    } else if (Length >= UNIT_MIB) {
        DTRACE("%d mib %s\n", Length / UNIT_MIB, Title);
    } else {
        DTRACE("%010d b %s\n", Length, Title);
    }
}

static VOID
MmProbeMemory(VOID)
{
    BPAL_HANDLE BpalHandle;
    MEMMAP_ENTRY Entry;
    UPTR EntryEnd;
    USIZE Idx;
    ST_STATUS Status;

    KeBpalGetHandle(&BpalHandle);
    for (Idx = 0;; ++Idx) {
        Status = BpalHandle.MemEntryIdx(Idx, &Entry);
        if (Status != STATUS_SUCCESS) {
            break;
        }

        EntryEnd = Entry.Base + Entry.Length;
        DTRACE("[%p - %p) ~ %s\n", Entry.Base, EntryEnd, MEM_TYPE(Entry.Type));

        /* Only usable entries from this point on */
        if (Entry.Type != MEMORY_USABLE) {
            continue;
        }

        UsableMemory += Entry.Length;
    }

    MmPrintUnits(UsableMemory, "avl");
}

VOID
MmInitPmm(VOID)
{
    DTRACE("sniffing out installed ram...\n");
    MmProbeMemory();
}