185 lines
6.7 KiB
C
185 lines
6.7 KiB
C
/*
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* This file is part of the libopencm3 project.
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*
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* Copyright (C) 2013 Andrzej Surowiec <emeryth@gmail.com>
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* Copyright (C) 2013 Pavol Rusnak <stick@gk2.sk>
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*
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* This library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <string.h>
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#include "ramdisk.h"
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#define WBVAL(x) ((x) & 0xFF), (((x) >> 8) & 0xFF)
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#define QBVAL(x) ((x) & 0xFF), (((x) >> 8) & 0xFF), \
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(((x) >> 16) & 0xFF), (((x) >> 24) & 0xFF)
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/* filesystem size is 512kB (1024 * SECTOR_SIZE) */
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#define SECTOR_COUNT 1024
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#define SECTOR_SIZE 512
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#define BYTES_PER_SECTOR 512
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#define SECTORS_PER_CLUSTER 4
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#define RESERVED_SECTORS 1
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#define FAT_COPIES 2
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#define ROOT_ENTRIES 512
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#define ROOT_ENTRY_LENGTH 32
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#define FILEDATA_START_CLUSTER 3
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#define DATA_REGION_SECTOR (RESERVED_SECTORS + FAT_COPIES + \
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(ROOT_ENTRIES * ROOT_ENTRY_LENGTH) / BYTES_PER_SECTOR)
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#define FILEDATA_START_SECTOR (DATA_REGION_SECTOR + \
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(FILEDATA_START_CLUSTER - 2) * SECTORS_PER_CLUSTER)
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/* filesize is 64kB (128 * SECTOR_SIZE) */
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#define FILEDATA_SECTOR_COUNT 128
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uint8_t BootSector[] = {
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0xEB, 0x3C, 0x90, /* code to jump to the bootstrap code */
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'm', 'k', 'd', 'o', 's', 'f', 's', 0x00, /* OEM ID */
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WBVAL(BYTES_PER_SECTOR), /* bytes per sector */
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SECTORS_PER_CLUSTER, /* sectors per cluster */
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WBVAL(RESERVED_SECTORS), /* # of reserved sectors (1 boot sector) */
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FAT_COPIES, /* FAT copies (2) */
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WBVAL(ROOT_ENTRIES), /* root entries (512) */
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WBVAL(SECTOR_COUNT), /* total number of sectors */
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0xF8, /* media descriptor (0xF8 = Fixed disk) */
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0x01, 0x00, /* sectors per FAT (1) */
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0x20, 0x00, /* sectors per track (32) */
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0x40, 0x00, /* number of heads (64) */
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0x00, 0x00, 0x00, 0x00, /* hidden sectors (0) */
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0x00, 0x00, 0x00, 0x00, /* large number of sectors (0) */
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0x00, /* drive number (0) */
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0x00, /* reserved */
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0x29, /* extended boot signature */
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0x69, 0x17, 0xAD, 0x53, /* volume serial number */
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'R', 'A', 'M', 'D', 'I', 'S', 'K', ' ', ' ', ' ', ' ', /* volume label */
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'F', 'A', 'T', '1', '2', ' ', ' ', ' ' /* filesystem type */
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};
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uint8_t FatSector[] = {
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0xF8, 0xFF, 0xFF, 0x00, 0x40, 0x00, 0x05, 0x60, 0x00, 0x07, 0x80, 0x00,
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0x09, 0xA0, 0x00, 0x0B, 0xC0, 0x00, 0x0D, 0xE0, 0x00, 0x0F, 0x00, 0x01,
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0x11, 0x20, 0x01, 0x13, 0x40, 0x01, 0x15, 0x60, 0x01, 0x17, 0x80, 0x01,
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0x19, 0xA0, 0x01, 0x1B, 0xC0, 0x01, 0x1D, 0xE0, 0x01, 0x1F, 0x00, 0x02,
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0x21, 0x20, 0x02, 0x23, 0x40, 0x02, 0x25, 0x60, 0x02, 0x27, 0x80, 0x02,
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0x29, 0xA0, 0x02, 0x2B, 0xC0, 0x02, 0x2D, 0xE0, 0x02, 0x2F, 0x00, 0x03,
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0x31, 0x20, 0x03, 0x33, 0x40, 0x03, 0x35, 0x60, 0x03, 0x37, 0x80, 0x03,
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0x39, 0xA0, 0x03, 0x3B, 0xC0, 0x03, 0x3D, 0xE0, 0x03, 0x3F, 0x00, 0x04,
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0x41, 0x20, 0x04, 0x43, 0x40, 0x04, 0x45, 0x60, 0x04, 0x47, 0x80, 0x04,
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0x49, 0xA0, 0x04, 0x4B, 0xC0, 0x04, 0x4D, 0xE0, 0x04, 0x4F, 0x00, 0x05,
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0x51, 0x20, 0x05, 0x53, 0x40, 0x05, 0x55, 0x60, 0x05, 0x57, 0x80, 0x05,
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0x59, 0xA0, 0x05, 0x5B, 0xC0, 0x05, 0x5D, 0xE0, 0x05, 0x5F, 0x00, 0x06,
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0x61, 0x20, 0x06, 0x63, 0x40, 0x06, 0x65, 0x60, 0x06, 0x67, 0x80, 0x06,
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0x69, 0xA0, 0x06, 0x6B, 0xC0, 0x06, 0x6D, 0xE0, 0x06, 0x6F, 0x00, 0x07,
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0x71, 0x20, 0x07, 0x73, 0x40, 0x07, 0x75, 0x60, 0x07, 0x77, 0x80, 0x07,
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0x79, 0xA0, 0x07, 0x7B, 0xC0, 0x07, 0x7D, 0xE0, 0x07, 0x7F, 0x00, 0x08,
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0x81, 0x20, 0x08, 0xFF, 0x0F, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00
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};
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uint8_t DirSector[] = {
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/* long filename entry */
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0x41, /* sequence number */
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WBVAL('r'), WBVAL('a'), WBVAL('m'), WBVAL('d'), WBVAL('i'), /* five name characters in UTF-16 */
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0x0F, /* attributes */
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0x00, /* type */
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0x00, /* checksum of DOS filename (computed in ramdisk_init) */
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WBVAL('s'), WBVAL('k'), WBVAL('.'), WBVAL('d'), WBVAL('a'), WBVAL('t'), /* six name characters in UTF-16 */
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0x00, 0x00, /* first cluster */
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WBVAL(0), WBVAL(0), /* two name characters in UTF-16 */
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/* actual entry */
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'R', 'A', 'M', 'D', 'I', 'S', 'K', ' ', /* filename */
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'D', 'A', 'T', /* extension */
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0x20, /* attribute byte */
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0x00, /* reserved for Windows NT */
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0x00, /* creation millisecond */
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0xCE, 0x01, /* creation time */
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0x86, 0x41, /* creation date */
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0x86, 0x41, /* last access date */
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0x00, 0x00, /* reserved for FAT32 */
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0xCE, 0x01, /* last write time */
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0x86, 0x41, /* last write date */
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WBVAL(FILEDATA_START_CLUSTER), /* start cluster */
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QBVAL(FILEDATA_SECTOR_COUNT * SECTOR_SIZE) /* file size in bytes */
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};
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static uint8_t ramdata[FILEDATA_SECTOR_COUNT * SECTOR_SIZE];
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int ramdisk_init(void)
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{
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uint32_t i = 0;
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/* compute checksum in the directory entry */
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uint8_t chk = 0;
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for (i = 32; i < 43; i++) {
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chk = (((chk & 1) << 7) | ((chk & 0xFE) >> 1)) + DirSector[i];
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}
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DirSector[13] = chk;
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/* fill ramdata */
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const uint8_t text[] = "USB Mass Storage Class example. ";
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i = 0;
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while (i < sizeof(ramdata)) {
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ramdata[i] = text[i % (sizeof(text) - 1)];
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i++;
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}
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return 0;
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}
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int ramdisk_read(uint32_t lba, uint8_t *copy_to)
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{
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memset(copy_to, 0, SECTOR_SIZE);
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switch (lba) {
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case 0: /* sector 0 is the boot sector */
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memcpy(copy_to, BootSector, sizeof(BootSector));
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copy_to[SECTOR_SIZE - 2] = 0x55;
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copy_to[SECTOR_SIZE - 1] = 0xAA;
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break;
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case 1: /* sector 1 is FAT 1st copy */
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case 2: /* sector 2 is FAT 2nd copy */
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memcpy(copy_to, FatSector, sizeof(FatSector));
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break;
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case 3: /* sector 3 is the directory entry */
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memcpy(copy_to, DirSector, sizeof(DirSector));
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break;
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default:
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/* ignore reads outside of the data section */
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if (lba >= FILEDATA_START_SECTOR &&
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lba < FILEDATA_START_SECTOR + FILEDATA_SECTOR_COUNT) {
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memcpy(copy_to, ramdata +
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(lba - FILEDATA_START_SECTOR) *
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SECTOR_SIZE,
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SECTOR_SIZE);
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}
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break;
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}
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return 0;
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}
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int ramdisk_write(uint32_t lba, const uint8_t *copy_from)
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{
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(void)lba;
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(void)copy_from;
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/* ignore writes */
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return 0;
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}
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int ramdisk_blocks(void)
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{
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return SECTOR_COUNT;
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}
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