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