file_system.c

/*****************************************************************************
* File Name: file_system.c
*
* Description:
*  This file provides the source code to emulate a file system. It only
*  contains a single file for read-only operations from the OS side and
*  write only operations from the firmware side.
*
* Note:
*
******************************************************************************
* Copyright (2020), Cypress Semiconductor Corporation.
******************************************************************************
* This software is owned by Cypress Semiconductor Corporation (Cypress) and is
* protected by and subject to worldwide patent protection (United States and
* foreign), United States copyright laws and international treaty provisions.
* Cypress hereby grants to licensee a personal, non-exclusive, non-transferable
* license to copy, use, modify, create derivative works of, and compile the
* Cypress Source Code and derivative works for the sole purpose of creating
* custom software in support of licensee product to be used only in conjunction
* with a Cypress integrated circuit as specified in the applicable agreement.
* Any reproduction, modification, translation, compilation, or representation of
* this software except as specified above is prohibited without the express
* written permission of Cypress.
*
* Disclaimer: CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH
* REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
* Cypress reserves the right to make changes without further notice to the
* materials described herein. Cypress does not assume any liability arising out
* of the application or use of any product or circuit described herein. Cypress
* does not authorize its products for use as critical components in life-support
* systems where a malfunction or failure may reasonably be expected to result in
* significant injury to the user. The inclusion of Cypress' product in a life-
* support systems application implies that the manufacturer assumes all risk of
* such use and in doing so indemnifies Cypress against all charges. Use may be
* limited by and subject to the applicable Cypress software license agreement.
*****************************************************************************/

#include "file_system.h"
#include "cy_utils.h"

#include <string.h>

/*******************************************************************************
* Constants
*******************************************************************************/
/* Jump Bootstrap Address */
#define FILE_SYSTEM_JUMP_BOOTSTRAP_VAL0     0xEB
#define FILE_SYSTEM_JUMP_BOOTSTRAP_VAL1     0x3C
#define FILE_SYSTEM_JUMP_BOOTSTRAP_VAL2     0x90

/* Media Type 
 *  0xF8 - standard value for non-removable disks 
 *  0xF0 - non partitioned removable disks */
#define FILE_SYSTEM_MEDIA_TYPE              0xF8

/* FAT Area */
#define FILE_SYSTEM_FAT_AREA_VAL0           0xF8
#define FILE_SYSTEM_FAT_AREA_VAL1           0xFF
#define FILE_SYSTEM_FAT_AREA_VAL2           0xFF
#define FILE_SYSTEM_FAT_AREA_VAL3           0xFF
#define FILE_SYSTEM_FAT_AREA_VAL4           0x0F

/* Directory Attribute 
 * 0x01: Read Only 
 * 0x02: Hidden
 * 0x03: System
 * 0x08: Volume Label 
 * 0x10: Directory
 * 0x20: Archive 
 * 0x0F: Long File Name */
#define FILE_SYSTEM_ATTRIBUTE_DRIVE         0x28
#define FILE_SYSTEM_ATTRIBUTE_LOG_FILE      0x01

/* Time 
 * Bit 15-11: Hours in range from 0 to 23
 * Bit 10-5:  Minutes in range from 0 to 59
 * Bit 4-0:   2 second count in range of form 0 to 29 (0-58 seconds) */
#define FILE_SYSTEM_TIME                    0x7B6E

/* Date
 * Bit 15-9: Count of years from 1980 in range of from 0 to 127 (1980-2107)
 * Bit 8-5:  Month of year in range from 1 to 12
 * Bit 4-0:  Day of month in range from 1 to 31 */
#define FILE_SYSTEM_DATE                    0x42B6

/* Cluster Address for the Log file */
#define FILE_SYSTEM_LOG_FILE_ADDRESS        2

/* File name and Extension define */
#define FILE_NAME_DEF(NAME,EXT) (NAME EXT)

/*******************************************************************************
* Global Variables
*******************************************************************************/
#ifdef CONFIG_LOG_MESSAGE
    const unsigned char initial_log_message[] = CONFIG_LOG_MESSAGE;
#endif

fat_fs_t file_system;
uint32_t file_system_write_count = 0;

/*******************************************************************************
* Function Name: file_system_init
********************************************************************************
* Summary:
*  Initialize the file system. It creates only one file in the system and its
*  content is placed in the internal SRAM.
*
* Parameters:
*  emulated_memory [out]: pointer to the memory. Note that the memory is
*  allocated internally.
*
*******************************************************************************/
void file_system_init(uint8_t **emulated_memory)
{
    uint8_t *content;

    *emulated_memory = (uint8_t *) &file_system;

    file_system_erase_all();

    /* Fill up the boot sector */
    file_system.boot.jump_bootstrap[0] = FILE_SYSTEM_JUMP_BOOTSTRAP_VAL0;
    file_system.boot.jump_bootstrap[1] = FILE_SYSTEM_JUMP_BOOTSTRAP_VAL1;
    file_system.boot.jump_bootstrap[2] = FILE_SYSTEM_JUMP_BOOTSTRAP_VAL2;
    file_system.boot.bytes_per_sector = FILE_SYSTEM_SECTOR_SIZE;
    file_system.boot.sectors_per_cluster = FILE_SYSTEM_SECTORS_PER_CLUSTER;
    file_system.boot.reserved_sectors = 1;
    file_system.boot.fat_copies = 1;
    file_system.boot.root_entries = FILE_SYSTEM_ROOT_DIRECTORIES_ENTRIES;
    file_system.boot.sectors_per_fs = FILE_SYSTEM_SECTORS_PER_FS;
    file_system.boot.media_type = FILE_SYSTEM_MEDIA_TYPE;
    file_system.boot.sectors_per_fat = FILE_SYSTEM_SECTORS_PER_FAT;
    file_system.boot.sectors_per_track = FILE_SYSTEM_SECTORS_PER_TRACK;
    file_system.boot.heads = 1;
    file_system.boot.signature = FILE_SYSTEM_SIGNATURE;

    /* Update FAT area */
    file_system.fat_area[0] = FILE_SYSTEM_FAT_AREA_VAL0;
    file_system.fat_area[1] = FILE_SYSTEM_FAT_AREA_VAL1;
    file_system.fat_area[2] = FILE_SYSTEM_FAT_AREA_VAL2;
    file_system.fat_area[3] = FILE_SYSTEM_FAT_AREA_VAL3;
    file_system.fat_area[4] = FILE_SYSTEM_FAT_AREA_VAL4;

    /* In the first entry, set the Mass Storage Device Name */
    memcpy(file_system.entries[0].filename, CONFIG_DRIVE_NAME, FILE_SYSTEM_FILENAME_SIZE);
    file_system.entries[0].attribute = FILE_SYSTEM_ATTRIBUTE_DRIVE;

    /* In the second entry, set up the LOG file */
    memcpy(file_system.entries[1].filename,FILE_NAME_DEF(CONFIG_LOG_FILE_NAME,CONFIG_LOG_FILE_EXTENSION), 11);
    file_system.entries[1].attribute = FILE_SYSTEM_ATTRIBUTE_LOG_FILE;
    file_system.entries[1].reserved[1] = 0x0E;
    file_system.entries[1].reserved[2] = 0xEB;
    file_system.entries[1].reserved[3] = 0x7C;
    file_system.entries[1].reserved[4] = 0xB6;
    file_system.entries[1].reserved[5] = 0x42;
    file_system.entries[1].reserved[6] = 0xB6;
    file_system.entries[1].reserved[7] = 0x42;
    file_system.entries[1].time = FILE_SYSTEM_TIME;
    file_system.entries[1].date = FILE_SYSTEM_DATE;
    file_system.entries[1].cluster = FILE_SYSTEM_LOG_FILE_ADDRESS;

#ifdef CONFIG_LOG_MESSAGE
    /* Point to the beginning of the content */
    content = file_system.clusters[0].content;

    /* Write the initial log message and update file size */
    memcpy(content, initial_log_message, sizeof(initial_log_message)-1);
    file_system.entries[1].filesize = sizeof(initial_log_message) - 1;
    file_system_write_count = sizeof(initial_log_message) - 1;
#endif
}

/*******************************************************************************
* Function Name: file_system_write
********************************************************************************
* Summary:
*  Writes data to the internal file located in SRAM.
*
* Parameters:
*  buf: pointer to the data
*  len: number of bytes to write
*
* Return:
*  True if successful. False if overflow the size of the file.
*
*******************************************************************************/
bool file_system_write(const char *buf, uint32_t len)
{
    bool status = false;
    uint8_t msgIndex = 0;
    uint8_t *content;

    if ((file_system_write_count + len) < (FILE_SYSTEM_DATASIZE))
    {
        content = (file_system.clusters[0].content);

        /* Status message. */
        for(msgIndex = 0; msgIndex < len; msgIndex++, file_system_write_count++)
        {
            content[file_system_write_count] = buf[msgIndex];
        }

        /* Set the new file size */
        file_system.entries[1].filesize = file_system_write_count;

        status = true;
    }

    return status;
}

/*******************************************************************************
* Function Name: file_system_erase_all
********************************************************************************
* Summary:
*  Erase the file content.
*
*******************************************************************************/
void file_system_erase_all(void)
{
    /* Fill the emulated memory with spaces. */
    memset(file_system.clusters, 0, FILE_SYSTEM_DATASIZE);

    file_system.entries[1].filesize = 0;
    file_system_write_count = 0;
}