--- /dev/null
+// SD CARD bitbanging code for loading files from a FAT16 forrmatted partition into memory
+//
+// Code is known to work on a de10nano with MiSTer SDRAM and IO Boards - IO Board has a secondary SD CARD interface connected to GPIO pins
+// SPI signals CLK, CS and MOSI are configured as GPIO output pins, and MISO is configued as GPIO input pins
+//
+// Protocol details developed from https://openlabpro.com/guide/interfacing-microcontrollers-with-sd-card/
+//
+// FAT16 details developed from https://codeandlife.com/2012/04/02/simple-fat-and-sd-tutorial-part-1/ and https://codeandlife.com/2012/04/07/simple-fat-and-sd-tutorial-part-2/
+
+// Import LiteX SoC details that are generated each time the SoC is compiled for the FPGA
+// csr defines the SPI Control registers
+// soc defines the clock CONFIG_CLOCK_FREQUENCY (50MHz for the VexRiscV processor on the MiSTer FPGA
+// mem defines the addresses for the SDRAM MAIN_RAM_BASE and MAIN_RAM_SIZE
+#include <generated/csr.h>
+#include <generated/soc.h>
+#include <generated/mem.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <string.h>
+
+#ifdef CSR_SPI_BASE
+// Import prototypes for the functions
+#include <spi.h>
+
+// SPI
+// cs line - high to indicate DESELECT
+// - low to indicate SELECT
+#define CS_HIGH 0x00
+#define CS_LOW 0x01
+
+// control register values
+// onebyte to indicate 1 byte being transferred
+// spi_start to indicate START of transfer
+// spi_done to indicate transfer DONE
+#define ONEBYTE 0x0800
+#define SPI_START 0x01
+#define SPI_DONE 0x01
+
+// Return values
+#define SUCCESS 0x01
+#define FAILURE 0x00
+
+// spi_write_byte
+// Send a BYTE (8bits) to the SD CARD
+// Seqeunce
+// Set MOSI
+// Set START bit and LENGTH=8
+// Await DONE
+//
+// No return values
+//
+// Details from https://openlabpro.com/guide/interfacing-microcontrollers-with-sd-card/ section "SD Commands"
+void spi_write_byte(unsigned char char_to_send);
+void spi_write_byte(unsigned char char_to_send)
+{
+ // Place data into MOSI register
+ // Pulse the START bit and set LENGTH=8
+ spi_mosi_write(char_to_send);
+ spi_control_write(ONEBYTE | SPI_START);
+
+ // Wait for DONE
+ while( (spi_status_read() != SPI_DONE)) {}
+
+ // Signal end of transfer
+ spi_control_write( 0x00 );
+}
+
+
+// spi_read_rbyte
+// Read a command response from the SD CARD - Equivalent to and R1 response or first byte of an R7 response
+// Sequence
+// Read MISO
+// If MSB != 0 then send dsummy byte and re-read MISO
+//
+// Return value is the response from the SD CARD
+// If the MSB is not 0, this would represent an ERROR
+// Calling function to determine if the correct response has been received
+//
+// Details from https://openlabpro.com/guide/interfacing-microcontrollers-with-sd-card/ section "SD Commands"
+unsigned char spi_read_rbyte(void);
+unsigned char spi_read_rbyte(void)
+{
+ int timeout=32;
+ unsigned char r=0;
+
+ // Check if MISO is 0x0xxxxxxx as MSB=0 indicates valid response
+ r = spi_miso_read();
+ while( ((r&0x80)!=0) && timeout>0) {
+ spi_mosi_write( 0xff );
+ spi_control_write(ONEBYTE | SPI_START);
+ while( (spi_status_read() != SPI_DONE)) {}
+ r = spi_miso_read();
+ spi_control_write( 0x00 );
+ timeout--;
+ }
+
+// printf("Done\n");
+ return r;
+}
+
+// spi_read_byte
+// Sequence
+// Send dummy byte
+// Read MISO
+//
+// Read subsequenct bytes from the SD CARD - MSB first
+// NOTE different from the spi_read_rbyte as no need to await an intial 0 bit as card is already responsing
+// Used to read additional response bytes, or data bytes from the SD CARD
+//
+// Return value is the byte read
+// NOTE no error status as assumed bytes are read via CLK pulses
+//
+// Details from https://openlabpro.com/guide/interfacing-microcontrollers-with-sd-card/ section "SD Commands"
+unsigned char spi_read_byte(void);
+unsigned char spi_read_byte(void)
+{
+ unsigned char r=0;
+
+ spi_write_byte( 0xff );
+ r = spi_miso_read();
+
+ return r;
+}
+
+// SETSPIMODE
+// Signal the SD CARD to switch to SPI mode
+// Pulse the CLK line HIGH/LOW repeatedly with MOSI and CS_N HIGH
+// Drop CS_N LOW and pulse the CLK
+// Check MISO for HIGH
+// Return 0 success, 1 failure
+//
+// Details from https://openlabpro.com/guide/interfacing-microcontrollers-with-sd-card/ section "Initializing the SD Card"
+unsigned char spi_setspimode(void);
+unsigned char spi_setspimode(void)
+{
+ unsigned int i, r, timeout=32;
+
+ // Initialise SPI mode
+ // set CS to HIGH
+ // Send pulses
+ do {
+ // set CS HIGH and send pulses
+ spi_cs_write(CS_HIGH);
+ for (i=0; i<10; i++) {
+ spi_write_byte( 0xff );
+ }
+
+ // set CS LOW and send pulses
+ spi_cs_write(CS_LOW);
+ r = spi_read_rbyte();
+
+ timeout--;
+ } while ( (timeout>0) && (r==0) );
+
+ if(timeout==0) return FAILURE;
+
+ return SUCCESS;
+}
+
+// SPI_SDCARD_GOIDLE
+// Function exposed to BIOS to initialise SPI mode
+//
+// Sequence
+// Set 100KHz timer mode
+// Send CLK pulses to set SD CARD to SPI mode
+// Send CMD0 - Software RESET - force SD CARD IDLE
+// Send CMD8 - Check SD CARD type
+// Send CMD55+ACMD41 - Force SD CARD READY
+// Send CMD58 - Read SD CARD OCR (status register)
+// Send CMD16 - Set SD CARD block size to 512 - Sector Size for the SD CARD
+// NOTE - Each command is prefixed with a dummy set of CLK pulses to prepare SD CARD to receive a command
+// Return 0 success, 1 failure
+//
+// Details from https://openlabpro.com/guide/interfacing-microcontrollers-with-sd-card/ section "Initializing the SD Card"
+unsigned char spi_sdcard_goidle(void)
+{
+ unsigned char r; // Response from SD CARD
+ int i, timeout; // TIMEOUT loop to send CMD55+ACMD41 repeatedly
+
+ r = spi_setspimode(); // Set SD CARD to SPI mode
+ if( r != 0x01 ) return FAILURE;
+
+ // CMD0 - Software reset - SD CARD IDLE
+ // Command Sequence is DUMMY=0xff CMD0=0x40 0x00 0x00 0x00 0x00 CRC=0x95
+ // Expected R1 response is 0x01 indicating SD CARD is IDLE
+ spi_write_byte( 0xff ); spi_write_byte( 0x40 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x95 );
+ r = spi_read_rbyte();
+ if(r!=0x01) return FAILURE;
+
+ // CMD8 - Check SD CARD type
+ // Command sequence is DUMMY=0xff CMD8=0x48 0x00 0x00 0x01 0xaa CRC=0x87
+ // Expected R7 response is 0x01 followed by 0x00 0x00 0x01 0xaa (these trailing 4 bytes not currently checked)
+ spi_write_byte( 0xff ); spi_write_byte( 0x48 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x01 ); spi_write_byte( 0xaa ); spi_write_byte( 0x87 );
+ r = spi_read_rbyte();
+ if(r!=0x01) return FAILURE;
+ // Receive the trailing 4 bytes for R7 response - FIXME should check for 0x00 0x00 0x01 0xaa
+ for(i=0; i<4; i++)
+ r=spi_read_byte();
+
+ // CMD55+ACMD41 - Force SD CARD READY - prepare card for reading/writing
+ // Command sequence is CMD55 followed by ACMD41
+ // Send commands repeatedly until SD CARD indicates READY 0x00
+ // CMD55 Sequence is DUMMY=0xff CMD55=0x77 0x00 0x00 0x00 0x00 CRC=0x00
+ // ACMD41 Sequence is DUMMY=0xff ACMD41=0x69 0x40 0x00 0x00 0x00 CRC=0x00
+ // Expected R1 response is 0x00 indicating SD CARD is READY
+ timeout=32;
+ do {
+ spi_write_byte( 0xff ); spi_write_byte( 0x77 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 );
+ r = spi_read_rbyte();
+
+ spi_write_byte( 0xff ); spi_write_byte( 0x69 ); spi_write_byte( 0x40 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 );
+ r = spi_read_rbyte();
+ timeout--;
+ } while ((r != 0x00) && (timeout>0));
+ if(r!=0x00) return FAILURE;
+
+ // CMD58 - Read SD CARD OCR (status register)
+ // FIXME - Find details on expected response from CMD58 to allow accurate checking of SD CARD R3 response
+ // Command sequence is DUMMY=0xff CMD58=0x7a 0x00 0x00 0x01 0xaa CRC=0xff
+ // Expected R3 response is 0x00 OR 0x01 followed by 4 (unchecked) trailing bytes
+ spi_write_byte( 0xff ); spi_write_byte( 0x7a ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0xff );
+ r = spi_read_rbyte();
+ if(r>0x01) return FAILURE;
+ // // Receive the trailing 4 bytes for R3 response
+ for(i=0; i<4; i++)
+ r=spi_read_byte();
+
+ // CMD16 - Set SD CARD block size to 512 - Sector Size for the SD CARD
+ // Command Sequence is DUMMY=0xff (512 as unsigned long = 0x00000200) 0x00 0x00 0x02 0x00 CRC=0xff
+ // Expected R1 response is 0x00 indicating SD CARD is READY
+ spi_write_byte( 0xff ); spi_write_byte( 0x50 ); spi_write_byte( 0x00 ); spi_write_byte( 0x00 ); spi_write_byte( 0x02 ); spi_write_byte( 0x00 ); spi_write_byte( 0xff );
+ r=spi_read_rbyte();
+ if(r!=0x00) return FAILURE;
+
+ return SUCCESS;
+}
+
+// READSECTOR
+// Read a 512 byte sector from the SD CARD
+// Given SECTORNUMBER and memory STORAGE
+//
+// Sequence
+// Send CMD17 - Read Block
+// Command Sequence is DUMMY=0xff CMD17=0x51 SECTORNUMBER (32bit UNSIGNED as bits 32-25,24-17, 16-9, 8-1) CRC=0xff
+// Wait for SD CARD to send 0x00 indicating SD CARD is processing
+// Wait for SD CARD to send 0xfe indicating SD CARD BLOCK START
+// Read 512 bytes
+// Read 8 DUMMY bytes
+// Return 0 success, 1 failure
+//
+// Details from https://openlabpro.com/guide/interfacing-microcontrollers-with-sd-card/ section "Read/Write SD Card"
+unsigned char readSector(unsigned int sectorNumber, unsigned char *storage);
+unsigned char readSector(unsigned int sectorNumber, unsigned char *storage)
+{
+ unsigned int n,timeout; // Number of bytes loop, timeout loop awaiting response bytes
+ unsigned char r; // Response bytes from SD CARD
+
+ // CMD17 - Read Block
+ // Command Sequence is DUMMY=0xff CMD17=0x51 SECTORNUMBER (32bit UNSIGNED as bits 32-25,24-17, 16-9, 8-1) CRC=0xff
+ // Expected R1 response is 0x00 indicating SD CARD is processing
+ spi_write_byte( 0xff ); spi_write_byte( 0x51 ); spi_write_byte( (sectorNumber>>24)&0xff ); spi_write_byte( (sectorNumber>>16)&0xff ); spi_write_byte( (sectorNumber>>8)&0xff ); spi_write_byte( (sectorNumber)&0xff ); spi_write_byte( 0xff );
+ r=spi_read_rbyte();
+ if( r!=0x00 ) return FAILURE;
+
+ // Await 0xfe to indicate BLOCK START
+ r=spi_read_byte();
+ timeout=16384;
+ while( (r!=0xfe) && (timeout>0) ) {
+ r=spi_read_byte();
+ timeout--;
+ }
+ if( r!=0xfe ) return FAILURE;
+
+ // Read 512 bytes into storage
+ for(n=0; n<512; n++)
+ storage[n]=spi_read_byte();
+
+ // Read 8 dummy bytes
+ for(n=0; n<8; n++)
+ r=spi_read_byte();
+
+ return SUCCESS;
+}
+
+
+// FAT16 Specific code starts here
+// Details from https://codeandlife.com/2012/04/02/simple-fat-and-sd-tutorial-part-1/
+
+// Structure to store SD CARD partition table
+typedef struct {
+ unsigned char first_byte;
+ unsigned char start_chs[3];
+ unsigned char partition_type;
+ unsigned char end_chs[3];
+ unsigned long start_sector;
+ unsigned long length_sectors;
+} __attribute((packed)) PartitionTable;
+
+PartitionTable sdCardPartition;
+
+// Structure to store SD CARD FAT16 Boot Sector (boot code is ignored, provides layout of the FAT16 partition on the SD CARD)
+typedef struct {
+ unsigned char jmp[3];
+ char oem[8];
+ unsigned short sector_size;
+ unsigned char sectors_per_cluster;
+ unsigned short reserved_sectors;
+ unsigned char number_of_fats;
+ unsigned short root_dir_entries;
+ unsigned short total_sectors_short; // if zero, later field is used
+ unsigned char media_descriptor;
+ unsigned short fat_size_sectors;
+ unsigned short sectors_per_track;
+ unsigned short number_of_heads;
+ unsigned long hidden_sectors;
+ unsigned long total_sectors_long;
+
+ unsigned char drive_number;
+ unsigned char current_head;
+ unsigned char boot_signature;
+ unsigned long volume_id;
+ char volume_label[11];
+ char fs_type[8];
+ char boot_code[448];
+ unsigned short boot_sector_signature;
+} __attribute((packed)) Fat16BootSector;
+
+Fat16BootSector sdCardFatBootSector;
+
+// Structure to store SD CARD FAT16 Root Directory Entries
+// Allocated to MAIN RAM - hence pointer
+typedef struct {
+ unsigned char filename[8];
+ unsigned char ext[3];
+ unsigned char attributes;
+ unsigned char reserved[10];
+ unsigned short modify_time;
+ unsigned short modify_date;
+ unsigned short starting_cluster;
+ unsigned long file_size;
+} __attribute((packed)) Fat16Entry;
+
+Fat16Entry *sdCardFat16RootDir;
+
+// Structure to store SD CARD FAT16 Entries
+// Array of UNSIGNED SHORTS (16bit integers)
+unsigned short *sdCardFatTable;
+
+// Calculated sector numbers on the SD CARD for the FAT16 Entries and ROOT DIRECTORY
+unsigned int fatSectorStart, rootDirSectorStart;
+
+// Storage for SECTOR read from SD CARD
+unsigned char sdCardSector[512];
+
+// SPI_SDCARD_READMBR
+// Function exposed to BIOS to retrieve FAT16 partition details, FAT16 Entry Table, FAT16 Root Directory
+// MBR = Master Boot Record - Sector 0x00000000 on SD CARD - Contains Partition 1 details at 0x1be
+//
+// FIXME only checks partition 1 out of 4
+//
+// Return 0 success, 1 failure
+//
+// Details from https://codeandlife.com/2012/04/02/simple-fat-and-sd-tutorial-part-1/
+unsigned char spi_sdcard_readMBR(void)
+{
+ int i, n;
+
+ // Read Sector 0x00000000
+ printf("Reading MBR\n");
+ if( readSector(0x00000000, sdCardSector)==SUCCESS ) {
+ // Copy Partition 1 Entry from byte 0x1be
+ // FIXME should check 0x55 0xaa at end of sector
+ memcpy(&sdCardPartition, &sdCardSector[0x1be], sizeof(PartitionTable));
+
+ // Check Partition 1 is valid, FIRST_BYTE=0x00 or 0x80
+ // Check Partition 1 has type 4, 6 or 14 (FAT16 of various sizes)
+ printf("Partition 1 Information: Active=0x%02x, Type=0x%02x, LBAStart=0x%08x\n", sdCardPartition.first_byte, sdCardPartition.partition_type, sdCardPartition.start_sector);
+ if( (sdCardPartition.first_byte!=0x80) && (sdCardPartition.first_byte!=0x00) ) {
+ printf("Partition 1 Not Valid\n");
+ return FAILURE;
+ }
+ if( (sdCardPartition.partition_type==4) || (sdCardPartition.partition_type==6) || (sdCardPartition.partition_type==14) ) {
+ printf("Partition 1 is FAT16\n");
+ }
+ else {
+ printf("Partition 1 Not FAT16\n");
+ return FAILURE;
+ }
+ }
+ else {
+ printf("Failed to read MBR\n");
+ return FAILURE;
+ }
+
+ // Read Parition 1 Boot Sector - Found from Partion Table
+ printf("\nRead FAT16 Boot Sector\n");
+ if( readSector(sdCardPartition.start_sector, sdCardSector)==SUCCESS ) {
+ memcpy(&sdCardFatBootSector, &sdCardSector, sizeof(Fat16BootSector));
+ }
+ else {
+ printf("Failed to read FAT16 Boot Sector\n");
+ return FAILURE;
+ }
+
+ // Print details of Parition 1
+ printf(" Jump Code: 0x%02x 0x%02x 0x%02x\n",sdCardFatBootSector.jmp[0],sdCardFatBootSector.jmp[1],sdCardFatBootSector.jmp[2]);
+ printf(" OEM Code: [");
+ for(n=0; n<8; n++)
+ printf("%c",sdCardFatBootSector.oem[n]);
+ printf("]\n");
+ printf(" Sector Size: %d\n",sdCardFatBootSector.sector_size);
+ printf(" Sectors Per Cluster: %d\n",sdCardFatBootSector.sectors_per_cluster);
+ printf(" Reserved Sectors: %d\n",sdCardFatBootSector.reserved_sectors);
+ printf(" Number of Fats: %d\n",sdCardFatBootSector.number_of_fats);
+ printf(" Root Dir Entries: %d\n",sdCardFatBootSector.root_dir_entries);
+ printf(" Total Sectors Short: %d\n",sdCardFatBootSector.total_sectors_short);
+ printf(" Media Descriptor: 0x%02x\n",sdCardFatBootSector.media_descriptor);
+ printf(" Fat Size Sectors: %d\n",sdCardFatBootSector.fat_size_sectors);
+ printf(" Sectors Per Track: %d\n",sdCardFatBootSector.sectors_per_track);
+ printf(" Number of Heads: %d\n",sdCardFatBootSector.number_of_heads);
+ printf(" Hidden Sectors: %d\n",sdCardFatBootSector.hidden_sectors);
+ printf(" Total Sectors Long: %d\n",sdCardFatBootSector.total_sectors_long);
+ printf(" Drive Number: 0x%02x\n",sdCardFatBootSector.drive_number);
+ printf(" Current Head: 0x%02x\n",sdCardFatBootSector.current_head);
+ printf(" Boot Signature: 0x%02x\n",sdCardFatBootSector.boot_signature);
+ printf(" Volume ID: 0x%08x\n",sdCardFatBootSector.volume_id);
+ printf(" Volume Label: [");
+ for(n=0; n<11; n++)
+ printf("%c",sdCardFatBootSector.volume_label[n]);
+ printf("]\n");
+ printf(" Volume Label: [");
+ for(n=0; n<8; n++)
+ printf("%c",sdCardFatBootSector.fs_type[n]);
+ printf("]\n");
+ printf(" Boot Sector Signature: 0x%04x\n\n",sdCardFatBootSector.boot_sector_signature);
+
+ // Check Partition 1 is valid, not 0 length
+ if(sdCardFatBootSector.total_sectors_long==0) {
+ printf("Error reading FAT16 Boot Sector\n");
+ return FAILURE;
+ }
+
+ // Read in FAT16 File Allocation Table, array of 16bit unsinged integers
+ // Calculate Storage from TOP of MAIN RAM
+ sdCardFatTable = (unsigned short *)(MAIN_RAM_BASE+MAIN_RAM_SIZE-sdCardFatBootSector.sector_size*sdCardFatBootSector.fat_size_sectors);
+ printf("sdCardFatTable = 0x%08x Reading Fat16 Table (%d Sectors Long)\n\n",sdCardFatTable,sdCardFatBootSector.fat_size_sectors);
+
+ // Calculate Start of FAT16 File Allocation Table (start of partition plus reserved sectors)
+ fatSectorStart=sdCardPartition.start_sector+sdCardFatBootSector.reserved_sectors;
+ for(n=0; n<sdCardFatBootSector.fat_size_sectors; n++) {
+ if( readSector(fatSectorStart+n, (unsigned char *)((unsigned char*)sdCardFatTable)+sdCardFatBootSector.sector_size*n)==FAILURE ) {
+ printf("Error reading FAT16 table - sector %d\n",n);
+ return FAILURE;
+ }
+ }
+
+ // Read in FAT16 Root Directory
+ // Calculate Storage from TOP of MAIN RAM
+ sdCardFat16RootDir= (Fat16Entry *)(MAIN_RAM_BASE+MAIN_RAM_SIZE-sdCardFatBootSector.sector_size*sdCardFatBootSector.fat_size_sectors-sdCardFatBootSector.root_dir_entries*sizeof(Fat16Entry));
+ printf("sdCardFat16RootDir = 0x%08x Reading Root Directory (%d Sectors Long)\n\n",sdCardFat16RootDir,sdCardFatBootSector.root_dir_entries*sizeof(Fat16Entry)/sdCardFatBootSector.sector_size);
+
+ // Calculate Start of FAT ROOT DIRECTORY (start of partition plues reserved sectors plus size of File Allocation Table(s))
+ rootDirSectorStart=sdCardPartition.start_sector+sdCardFatBootSector.reserved_sectors+sdCardFatBootSector.number_of_fats*sdCardFatBootSector.fat_size_sectors;
+ for(n=0; n<sdCardFatBootSector.root_dir_entries*sizeof(Fat16Entry)/sdCardFatBootSector.sector_size; n++) {
+ if( readSector(rootDirSectorStart+n, (unsigned char *)(sdCardFatBootSector.sector_size*n+(unsigned char *)(sdCardFat16RootDir)))==FAILURE ) {
+ printf("Error reading Root Dir - sector %d\n",n);
+ return FAILURE;
+ }
+ }
+
+ // Print out Root Directory
+ // Alternates between valid and invalid directory entries for SIMPLE 8+3 file names, extended filenames in other entries
+ // Only print valid characters
+ printf("\nRoot Directory\n");
+ for(n=0; n<sdCardFatBootSector.root_dir_entries; n++) {
+ if( (sdCardFat16RootDir[n].filename[0]!=0) && (sdCardFat16RootDir[n].file_size>0)) {
+ printf(" File %d [",n);
+ for( i=0; i<8; i++) {
+ if( (sdCardFat16RootDir[n].filename[i]>31) && (sdCardFat16RootDir[n].filename[i]<127) )
+ printf("%c",sdCardFat16RootDir[n].filename[i]);
+ else
+ printf(" ");
+ }
+ printf(".");
+ for( i=0; i<3; i++) {
+ if( (sdCardFat16RootDir[n].ext[i]>31) && (sdCardFat16RootDir[n].ext[i]<127) )
+ printf("%c",sdCardFat16RootDir[n].ext[i]);
+ else
+ printf(" ");
+ }
+ printf("] @ Cluster %d for %d bytes\n",sdCardFat16RootDir[n].starting_cluster,sdCardFat16RootDir[n].file_size);
+ }
+ }
+
+ printf("\n");
+ return SUCCESS;
+}
+
+// SPI_SDCARD_READFILE
+// Function exposed to BIOS to retrieve FILENAME+EXT into ADDRESS
+//
+// FIXME only checks UPPERCASE 8+3 filenames
+//
+// Return 0 success, 1 failure
+//
+// Details from https://codeandlife.com/2012/04/02/simple-fat-and-sd-tutorial-part-1/
+unsigned char spi_sdcard_readFile(char *filename, char *ext, unsigned long address)
+{
+ int i, n, sector;
+ unsigned short fileClusterStart;
+ unsigned long fileLength, bytesRemaining, clusterSectorStart;
+ unsigned short nameMatch;
+ printf("Reading File [%s.%s] into 0x%08x : ",filename, ext, address);
+
+ // Find FILENAME+EXT in Root Directory
+ // Indicate FILE found by setting the starting cluster number
+ fileClusterStart=0; n=0;
+ while( (fileClusterStart==0) && (n<sdCardFatBootSector.root_dir_entries) ) {
+ nameMatch=0;
+ if( sdCardFat16RootDir[n].filename[0]!=0 ) {
+ nameMatch=1;
+ for(i=0; i<strlen(filename); i++)
+ if(sdCardFat16RootDir[n].filename[i]!=filename[i]) nameMatch=0;
+ for(i=0; i<strlen(ext); i++)
+ if(sdCardFat16RootDir[n].ext[i]!=ext[i]) nameMatch=0;
+ }
+
+ if(nameMatch==1) {
+ fileClusterStart=sdCardFat16RootDir[n].starting_cluster;
+ fileLength=sdCardFat16RootDir[n].file_size;
+ } else {
+ n++;
+ }
+ }
+
+ // If starting cluster number is still 0 then file not found
+ if(fileClusterStart==0) {
+ printf("File not found\n");
+ return FAILURE;
+ }
+
+ printf("File starts at Cluster %d length %d\n",fileClusterStart,fileLength);
+
+ // ZERO Length file are automatically assumed to have been read SUCCESS
+ if( fileLength==0 ) return SUCCESS;
+
+ // Read each cluster sector by sector, i being number of clusters
+ bytesRemaining=fileLength;
+ printf("Clusters: ");
+ // Calculate number of clusters (always >1)
+ for(i=0; i<1+((fileLength/sdCardFatBootSector.sectors_per_cluster)/sdCardFatBootSector.sector_size); i++) {
+ printf("%d ",fileClusterStart);
+
+ // Locate start of cluster on SD CARD and read appropraite number of sectors
+ clusterSectorStart=rootDirSectorStart+(fileClusterStart-1)*sdCardFatBootSector.sectors_per_cluster;
+ for(sector=0; sector<sdCardFatBootSector.sectors_per_cluster; sector++) {
+ // Read Sector from SD CARD
+ // If whole sector to be read, read directly into memory
+ // Otherwise, read to sdCardSector buffer and transfer appropriate number of bytes
+ if(bytesRemaining>sdCardFatBootSector.sector_size) {
+ if( readSector(clusterSectorStart+sector,(unsigned char *)address) == FAILURE ) {
+ printf("Read Error\n");
+ return FAILURE;
+ }
+ bytesRemaining=bytesRemaining-sdCardFatBootSector.sector_size;
+ address=address+sdCardFatBootSector.sector_size;
+ } else {
+ if( readSector(clusterSectorStart+sector,sdCardSector) == FAILURE ) {
+ printf("Read Error\n");
+ return FAILURE;
+ }
+ memcpy((unsigned char *)address, sdCardSector, bytesRemaining);
+ bytesRemaining=0;
+ }
+ }
+
+ // Move to next cluster
+ fileClusterStart=sdCardFatTable[fileClusterStart];
+ }
+ printf("\n\n");
+ return SUCCESS;
+}
+#endif
projects / litex.git / commitdiff