From 400fd7489766a3f2aa4520a8ee73b04aa30f3b87 Mon Sep 17 00:00:00 2001
From: Michael Brown <mcb30@etherboot.org>
Date: Mon, 18 Apr 2005 15:39:02 +0000
Subject: [PATCH] Extracted from firmware/pcbios/bios.c

---
 src/arch/i386/drivers/bus/bios_disks.c | 56 ++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 src/arch/i386/drivers/bus/bios_disks.c

diff --git a/src/arch/i386/drivers/bus/bios_disks.c b/src/arch/i386/drivers/bus/bios_disks.c
new file mode 100644
index 00000000..d765111d
--- /dev/null
+++ b/src/arch/i386/drivers/bus/bios_disks.c
@@ -0,0 +1,56 @@
+#include "realmode.h"
+
+#define CF ( 1 << 0 )
+
+/**************************************************************************
+DISK_INIT - Initialize the disk system
+**************************************************************************/
+void disk_init ( void ) {
+	REAL_EXEC ( rm_disk_init,
+		    "sti\n\t"
+		    "xorw %%ax,%%ax\n\t"
+		    "movb $0x80,%%dl\n\t"
+		    "int $0x13\n\t"
+		    "cli\n\t",
+		    0,
+		    OUT_CONSTRAINTS (),
+		    IN_CONSTRAINTS (),
+   		    CLOBBER ( "eax", "ebx", "ecx", "edx",
+			      "ebp", "esi", "edi" ) );
+}
+
+/**************************************************************************
+DISK_READ - Read a sector from disk
+**************************************************************************/
+unsigned int pcbios_disk_read ( int drive, int cylinder, int head, int sector,
+				char *fixme_buf ) {
+	uint16_t ax, flags, discard_c, discard_d;
+	segoff_t buf = SEGOFF ( fixme_buf );
+
+	/* FIXME: buf should be passed in as a segoff_t rather than a
+	 * char *
+	 */
+
+	REAL_EXEC ( rm_pcbios_disk_read,
+		    "sti\n\t"
+		    "pushl %%ebx\n\t"	   /* Convert %ebx to %es:bx */
+		    "popw %%bx\n\t"
+		    "popw %%es\n\t"
+		    "movb $0x02, %%ah\n\t" /* INT 13,2 - Read disk sector */
+		    "movb $0x01, %%al\n\t" /* Read one sector */
+		    "int $0x13\n\t"
+		    "pushfw\n\t"
+		    "popw %%bx\n\t"
+		    "cli\n\t",
+		    4,
+		    OUT_CONSTRAINTS ( "=a" ( ax ), "=b" ( flags ),
+				      "=c" ( discard_c ), "=d" ( discard_d ) ),
+		    IN_CONSTRAINTS ( "c" ( ( ( cylinder & 0xff ) << 8 ) |
+					   ( ( cylinder >> 8 ) & 0x3 ) |
+					   sector ),
+				     "d" ( ( head << 8 ) | drive ),
+				     "b" ( buf ) ),
+		    CLOBBER ( "ebp", "esi", "edi" ) );
+
+	return ( flags & CF ) ? ax : 0;
+}