add disk read

not implementing disk write yet

boot/boot.c

@@ -10,6 +10,7 @@ void (*probe1[])(void) = {
 	cpuidprobe,
 };
 void (*probe2[])(void) = {
+	diskprobe,
 };
 
 BootProbe probes[] = {
@@ -102,11 +103,9 @@ boot(int bootdev)
 	fmtinstall('D', fmtdisk);
 	print("\n===> Hello world <===\n\t"
 		"Booted on disk 0x%x debug:%d\n\t", bootdev, debug);
-	machdep();	
+	machdep();
 
 	bdiskget(bootdev, &d);
-	print("%D\n%D", d,d);
-
 	for(;;){
 		char buf[8192];
 

boot/dat.h

@@ -7,6 +7,9 @@
 #define BOOT_DEBUG 1
 #endif
 
+#define DOSPARTOFF 446
+#define NDOSPART 4
+
 enum{
 	CON_PC,
 	CON_SRI,
@@ -57,6 +60,25 @@ typedef struct{
 }Op;
 
 // disk.c
+typedef struct{
+	u8 flag;	/* bootstrap flags */
+	u8 bhd;	/* begin head */
+	u8 bsec;	/* begin sector */
+	u8 bcyl;	/* begin cylinder */
+	u8 type;	/* partition type (see below) */
+	u8 ehd;	/* end head */
+	u8 esec;	/* end sec2r */
+	u8 ecyl;	/* end cylinder */
+	u32 beg;	/* absolute starting sectoff number */
+	u32 size;	/* partition size in sec2rs */
+} __attribute__((packed)) DOSpart;
+
+typedef struct{
+	u8 boot[DOSPARTOFF];
+	DOSpart parts[NDOSPART];
+	u16 sign;
+} __attribute__((packed)) DOSmbr;
+
 typedef struct{
 	int n;
 	u32 ncyl;
@@ -68,6 +90,17 @@ typedef struct{
 	u32 flag;
 } __attribute__((packed)) BIOSdisk;
 
+typedef struct{
+
+}Disklabel;
+
+typedef struct{
+	BIOSdisk bdsk;	// bios disk info
+	Disklabel label;
+
+	int bootdev, osdev;
+}Disk;
+
 // gdt.S
 extern volatile struct BIOSreg BIOSreg;
 

boot/disk.c

@@ -2,6 +2,14 @@
 #include "dat.h"
 #include "fn.h"
 
+#define BDA_DISK 0x0475	// of hard disk drives detected
+#define MAX_DISK_ENTRY 1	// for now
+
+enum{
+	Bread = 0x4200,
+	Bwrite = 0x4300,
+};
+
 // interrupt 41h exension support bitmap
 enum{
 	Eeda	= 0x01,	// Extended disk access funcions 42-44,47,48
@@ -9,6 +17,18 @@ enum{
 	Eedd	= 0x04,	// Enhanced disk drive functions
 };
 
+typedef struct{
+	u8 len;
+	u8 res1;
+	u8 nblk;
+	u8 res2;
+	u16 off;
+	u16 seg;
+	u64 daddr; // starting block
+}EDDcb;
+
+Disk disks[MAX_DISK_ENTRY];
+
 static int
 ireset(int dev)
 {
@@ -81,6 +101,67 @@ bdiskget(int dev, BIOSdisk *d)
 	return 0;
 }
 
+static int
+diskrw(uint rw, int dev, u32 daddr, u32 blk, void *buf)
+{
+	int rv;
+	volatile EDDcb cb = {0,};
+
+	cb.len = sizeof(cb);
+	cb.nblk = blk;
+	cb.seg = ((u32)buf>>4 & 0xffff);
+	cb.off = (u32)buf & 0xf;
+	cb.daddr = daddr;
+	if(cb.seg==0 || cb.off==0)
+		return -1;
+	BIOSreg.ds = (u32)&cb >> 4;
+	__asm volatile ("int $0x33\n\t"
+					"setc %b0\n\t"
+					: "=a" (rv)
+					: "0" (rw), "d" (dev), "S" ((int)(&cb)&0xf)
+					: "%ecx", "cc");
+	return rv&0xff? -1 : 0;
+}
+
+static int
+findos(BIOSdisk *bd)
+{
+	DOSmbr mbr = {0,};
+
+	if(diskrw(Bread, bd->n, 0, 1, &mbr)){
+		print("Can't find os disk %d\n", bd->n);
+		return -1;
+	}
+	print("found os disk signature: 0x%x\n", mbr.sign);
+	return 0;
+}
+
+static int
+findlabel(BIOSdisk *b, Disklabel *dl)
+{
+	if(b->n & 0x80){
+		findos(b);
+		return 0;	// for now
+	}
+	print("Can't found disk label:%x \n", b->n);
+	return -1;
+}
+
+void
+diskprobe(void)
+{
+	int n = MIN((int)*(char*)BDA_DISK, MAX_DISK_ENTRY);
+
+	for(int i = 0x80; i < 0x80+n; ++i){
+		if(bdiskget(i, &disks[i].bdsk))
+			return;
+		print("Disnk info: %D\n", disks[i].bdsk);
+		if(findlabel(&disks[i].bdsk, &disks[i].label)){
+
+		}
+	}
+}
+
 int
 fmtdisk(Op *op)
 {

boot/fn.h

@@ -44,6 +44,7 @@ void free(void*);
 // disk.c
 int bdiskget(int dev, BIOSdisk *d);
 int fmtdisk(Op *op);
+void diskprobe(void);
 
 // util
 void* memset(void *dst, int v, int l);