1 files changed, 160 insertions, 0 deletions
diff --git a/emb/pastilda/hw/usb_device/ramdisk.c b/emb/pastilda/hw/usb_device/ramdisk.c
new file mode 100644
index 0000000..15ea8a1
--- /dev/null
+++ b/emb/pastilda/hw/usb_device/ramdisk.c
@@ -0,0 +1,160 @@
+#include <string.h>
+#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);
+}