Changeset 46947 in vbox for trunk/src/VBox/Devices/PC/BIOS

Timestamp:

Jul 3, 2013 5:39:01 PM (12 years ago)

Author:

vboxsync

Message:

VBoxPcBios: Use HLT while waiting for floppy interrupts. Added comment on seemingly missing 00440h updating in the int08_handler.

Location:

trunk/src/VBox/Devices/PC/BIOS

Files:

• floppy.c (modified) (15 diffs)
• inlines.h (modified) (1 diff)
• orgs.asm (modified) (1 diff)

trunk/src/VBox/Devices/PC/BIOS/floppy.c

@@ -72 +72 @@
 extern  int     diskette_param_table;   /* At a fixed location. */
 
+#ifndef VBOX_WITH_FLOPPY_IRQ_POLLING
+
+/**
+ * Wait for the 7th bit of 0040:003e to be set by int0e_handler.
+ * @returns first 7 bits of byte 0040:003e, interrupts disabled.
+ */
+uint8_t floppy_wait_for_interrupt(void)
+{
+    int_disable();
+    for (;;)
+    {
+        uint8_t val8 = read_byte(0x0040, 0x003e);
+        if (val8 & 0x80)
+            return val8 & ~0x7f;
+        int_enable_hlt_disable();
+    }
+}
+
+/**
+ * Wait for the 7th bit of 0040:003e to be set by int0e_handler or 0040:0040 to
+ * be cleared by the timer, clearing the interrupt flag on success.
+ *
+ * @returns 0 on timeout with interrupts enabled.
+ *          All 8 bits at 0040:003e on interrupt with interrupts disabled (i.e.
+ *          non-zero), after first clearing the 7th bit at 0040:003e.
+ */
+uint8_t floppy_wait_for_interrupt_or_timeout(void)
+{
+    int_disable();
+    for (;;)
+    {
+        uint8_t val8 = read_byte(0x0040, 0x0040);
+        if (val8 == 0) {
+            int_enable();
+            return 0;
+        }
+
+        val8 = read_byte(0x0040, 0x003e);
+        if (val8 & 0x80) {
+            write_byte(0x0040, 0x003e, val8 & 0x7f);
+            return val8;
+        }
+        int_enable_hlt_disable();
+    }
+}
+
+#endif /* !VBOX_WITH_FLOPPY_IRQ_POLLING */
+
 void floppy_reset_controller(void)
 {
@@ -107 +155 @@
     
     // reset the disk motor timeout value of INT 08
-    write_byte(0x40,0x40, BX_FLOPPY_ON_CNT);
+    write_byte(0x0040,0x0040, BX_FLOPPY_ON_CNT);
     
     // program data rate
@@ -120 +168 @@
     
     if (prev_reset == 0) {
+#ifdef VBOX_WITH_FLOPPY_IRQ_POLLING
         // turn on interrupts
         int_enable();
@@ -128 +177 @@
         val8 &= 0x7f;
         int_disable();
+#else
+        val8 = floppy_wait_for_interrupt(); /* (7th bit cleared in ret val) */
+#endif
         write_byte(0x0040, 0x003e, val8);
     }
@@ -159 +211 @@
 bx_bool floppy_read_id(uint16_t drive)
 {
+#ifdef VBOX_WITH_FLOPPY_IRQ_POLLING
     uint8_t     val8;
+#endif
     uint8_t     return_status[7];
     int         i;
@@ -169 +223 @@
     outb(0x03f5, drive); // 0=drive0, 1=drive1, head always 0
     
+#ifdef VBOX_WITH_FLOPPY_IRQ_POLLING
     // turn on interrupts
     int_enable();
@@ -180 +235 @@
     // turn off interrupts
     int_disable();
+#else
+    floppy_wait_for_interrupt();
+#endif
     
     // read 7 return status bytes from controller
@@ -203 +261 @@
     outb(0x03f5, drive); // 0=drive0, 1=drive1
     
+#ifdef VBOX_WITH_FLOPPY_IRQ_POLLING
     // turn on interrupts
     int_enable();
@@ -214 +273 @@
     // turn off interrupts
     int_disable();
-    
+
     // set 40:3e bit 7 to 0, and calibrated bit
     val8 = read_byte(0x0040, 0x003e);
     val8 &= 0x7f;
+#else
+    val8 = floppy_wait_for_interrupt(); /* (7th bit cleared in ret val) */
+
+    // set 40:3e bit 7 to 0, and calibrated bit
+#endif
     if (drive) {
         val8 |= 0x02; // Drive 1 calibrated
@@ -563 +627 @@
             outb(0x03f5, 0xff); // Gap length
             
+#ifdef VBOX_WITH_FLOPPY_IRQ_POLLING
             // turn on interrupts
             int_enable();
             
-            // wait on 40:3e bit 7 to become 1
+            // wait on 40:3e bit 7 to become 1 or timeout (latter isn't armed so it won't happen)
             do {
-                    val8 = read_byte(0x0040, 0x0040);
+                val8 = read_byte(0x0040, 0x0040);
                 if (val8 == 0) {
                     floppy_reset_controller();
@@ -583 +648 @@
             // turn off interrupts
             int_disable();
-            
+
             // set 40:3e bit 7 to 0
             val8 = read_byte(0x0040, 0x003e);
             val8 &= 0x7f;
             write_byte(0x0040, 0x003e, val8);
+
+#else
+            val8 = floppy_wait_for_interrupt_or_timeout();
+            if (val8 == 0) { /* Note! Interrupts enabled in this branch. */
+                floppy_reset_controller();
+                SET_AH(0x80); // drive not ready (timeout)
+                set_diskette_ret_status(0x80);
+                SET_AL(0); // no sectors read
+                SET_CF(); // error occurred
+                return;
+            }
+#endif
             
             // check port 3f4 for accessibility to status bytes
@@ -686 +763 @@
             outb(0x03f5, 0xff); // Gap length
             
+#ifdef VBOX_WITH_FLOPPY_IRQ_POLLING
             // turn on interrupts
             int_enable();
@@ -706 +784 @@
             // turn off interrupts
             int_disable();
-            
+
             // set 40:3e bit 7 to 0
             val8 = read_byte(0x0040, 0x003e);
             val8 &= 0x7f;
             write_byte(0x0040, 0x003e, val8);
+#else
+            val8 = floppy_wait_for_interrupt_or_timeout();
+            if (val8 == 0) { /* Note! Interrupts enabled in this branch. */
+                floppy_reset_controller();
+                SET_AH(0x80); // drive not ready (timeout)
+                set_diskette_ret_status(0x80);
+                SET_AL(0); // no sectors written
+                SET_CF(); // error occurred
+                return;
+            }
+#endif
             
             // check port 3f4 for accessibility to status bytes
@@ -835 +924 @@
         outb(0x03f5, 0); // Gap length
         outb(0x03f5, 0xf6); // Fill byte
+
+#ifdef VBOX_WITH_FLOPPY_IRQ_POLLING
         // turn on interrupts
         int_enable();
@@ -854 +945 @@
         // turn off interrupts
         int_disable();
+
         // set 40:3e bit 7 to 0
         val8 = read_byte(0x0040, 0x003e);
         val8 &= 0x7f;
         write_byte(0x0040, 0x003e, val8);
+#else
+        val8 = floppy_wait_for_interrupt_or_timeout();
+        if (val8 == 0) { /* Note! Interrupts enabled in this branch. */
+            floppy_reset_controller();
+            SET_AH(0x80); // drive not ready (timeout)
+            set_diskette_ret_status(0x80);
+            SET_CF(); // error occurred
+            return;
+        }
+#endif
+
         // check port 3f4 for accessibility to status bytes
         val8 = inb(0x3f4);

trunk/src/VBox/Devices/PC/BIOS/inlines.h

@@ -38 +38 @@
 void int_disable(void);
 #pragma aux int_disable = "cli" modify exact [] nomemory;
+
+void int_enable_hlt_disable(void);
+#pragma aux int_enable_hlt_disable = \
+    "sti" \
+    "hlt" \
+    "cli" \
+    modify exact [] nomemory;
 
 uint16_t int_query(void);

trunk/src/VBox/Devices/PC/BIOS/orgs.asm

@@ -1722 +1722 @@
 
                 ;; time to turn off floppy driv motor(s)?
-                mov     al, ds:[440h]
+                mov     al, ds:[440h]    ;; @todo Shouldn't this be decreased if > 0? How would we ever get to zero otherwise?
                 or      al, al
                 jz      int08_floppy_off