#include "../include/multiboot2.h"

uintptr_t multiboot2_boot_info_addr;
uint32_t multiboot2_magic;
uint32_t multiboot2_boot_info_size;

bool multiboot2_init(uint32_t info_addr) {
    multiboot2_boot_info_addr = info_addr;
    uintptr_t *addr = (uintptr_t *) multiboot2_boot_info_addr;
    if (multiboot2_magic != MULTIBOOT2_BOOTLOADER_MAGIC)
        return false;
    // addr+0 处保存了大小
    multiboot2_boot_info_size = *(uint32_t *) addr;
    return true;
}

void multiboot2_iter(bool (*_fun)(const struct iter_data_t *, void *, uint32_t *),
                     void *data, uint32_t *count) {

    uintptr_t addr = multiboot2_boot_info_addr;
    // 接下来的第8字节开始，为 tag 信息
    struct iter_data_t *tag = (struct iter_data_t *) ((void *) addr + 8);
    for (; tag->type != MULTIBOOT_TAG_TYPE_END;
           tag = (struct iter_data_t *) ((uint8_t *) tag + ALIGN_F(tag->size, 8))) {

        if (_fun(tag, data, count) == true) {
            return;
        }
    }
    return;
}

// 读取 grub2 传递的物理内存信息，保存到 e820map_t 结构体中
// 一般而言是这样的
// 地址(长度) 类型
// 0x00(0x9F000) 0x1
// 0x9F000(0x1000) 0x2
// 0xE8000(0x18000) 0x2
// 0x100000(0x7EF0000) 0x1
// 0x7FF0000(0x10000) 0x3
// 0xFFFC0000(0x40000) 0x2
/**
 * @brief 获取multiboot2协议提供的内存区域信息
 *
 * @param _iter_data 要被迭代的信息的结构体
 * @param _data 返回信息的结构体指针
 * @param count 返回数组的长度
 * @return true
 * @return false
 */
bool multiboot2_get_memory(const struct iter_data_t *_iter_data, void *data, uint32_t *count) {
    if (_iter_data->type != MULTIBOOT_TAG_TYPE_MMAP)
        return false;

    struct multiboot_mmap_entry_t *resource = (struct multiboot_mmap_entry_t *) data;
    struct multiboot_mmap_entry_t *mmap = ((struct multiboot_tag_mmap_t *) _iter_data)->entries;
    *count = 0;
    for (; (uint8_t *) mmap < (uint8_t *) _iter_data + _iter_data->size;
           mmap = (struct multiboot_mmap_entry_t *) ((uint8_t *) mmap +
                                                     ((struct multiboot_tag_mmap_t *) _iter_data)->entry_size)) {
        *resource = *mmap;
        // 将指针进行增加
        resource = (struct multiboot_mmap_entry_t *) ((uint8_t *) resource +
                                                      ((struct multiboot_tag_mmap_t *) _iter_data)->entry_size);
        ++(*count);
    }
    return true;
}

/**
 * @brief 获取VBE信息
 *
 * @param _iter_data 要被迭代的信息的结构体
 * @param _data 返回信息的结构体指针
 */
bool multiboot2_get_VBE_info(const struct iter_data_t *_iter_data, void *data, uint32_t *reserved) {

    if (_iter_data->type != MULTIBOOT_TAG_TYPE_VBE)
        return false;
    *(struct multiboot_tag_vbe_t *) data = *(struct multiboot_tag_vbe_t *) _iter_data;
    return true;
}

/**
 * @brief 获取帧缓冲区信息
 *
 * @param _iter_data 要被迭代的信息的结构体
 * @param _data 返回信息的结构体指针
 */
bool multiboot2_get_Framebuffer_info(const struct iter_data_t *_iter_data, void *data, uint32_t *reserved) {
    if (_iter_data->type != MULTIBOOT_TAG_TYPE_FRAMEBUFFER)
        return false;
    *(struct multiboot_tag_framebuffer_info_t *) data = *(struct multiboot_tag_framebuffer_info_t *) _iter_data;
    return true;
}