LCOM1920-T02G10

#pragma once

/** @defgroup liblm liblm

 * @{

 *

 * Functions related to low memory (first 1 MB of physical memory), required for BIOS

 */

#include <stdbool.h>

#include <minix/syslib.h>

#define PB2BASE(x) (((x) >> 4) & 0x0F000) // phys_bytes to segment base

#define PB2OFF(x) ((x) & (0x0FFFF))       // phys_bytes to segment offset

/** @name Memory Map Struct*/

/**@{

 *

 * Struct that keeps info regarding the mapping of physical memory to virtual memory

 */

typedef struct {

  phys_bytes phys; /**< @brief physical address */

  void *virt;      /**< @brief virtual address */

  size_t size;     /**< @brief size of mapped memory region */

} mmap_t;

/** @} end of Memory Map Struct */

/**

 * @brief Initializes the low memory area, the region up to the 1 MByte physical address, by mapping it on the process' physical memory address

 * 

 * @param enable_logging set whether log messages should be printed or not

 *

 * @return virtual address on which the first 1 MB was mapped, NULL upon failure

 */

void *lm_init(bool enable_logging);

/**

 * @brief Allocates a memory block in low memory area with the specified size

 * 

 * Allocates a memory block in the region up to the 1 MByte physical address with the input size,

 *  and initializes the input mmap_t struct with the mapping information.

 * 

 * @param size size of the memory block to allocate

 * @param map pointer to mmap_t data structure, which represents the memory map

 * @return the virtual address of the memory block on success, NULL otherwise

 */

void *lm_alloc(size_t size, mmap_t *map);

/**

 * @brief Frees a memory block in the low memory area, previously allocated using lm_alloc()

 * 

 * Frees a memory block in the region up to the 1 MByte physical address, previously

 *  allocated using lm_alloc(). Takes as input the address of the mmap_t structure that

 *  was passed to lm_alloc(), and that must have not been modified since.

 * 

 * @param map pointer to mmap_t data structure of the block being freed

 * @return a boolean indicating whether memory deallocation succeeded

 */

bool lm_free(const mmap_t *map);

/** @} end of liblm */