fdc: fix/rewrite seek, media_changed and interrupt handling

index 30d34e3..be35201 100644
@@ -159,6 +159,10 @@ static int fd_seek(FDrive *drv, uint8_t head, uint8_t track, uint8_t sect,
         drv->sect = sect;
     }
 
+    if (drv->bs == NULL || !bdrv_is_inserted(drv->bs)) {
+        ret = 2;
+    }
+
     return ret;
 }
 

index 22d24ac..e730398 100644
@@ -49,6 +49,7 @@ enum {
 enum {
     CMD_SENSE_INT   = 0x08,
     CMD_SEEK        = 0x0f,
+    CMD_READ        = 0xe6,
 };
 
 enum {

@@ -99,6 +100,62 @@ static void ack_irq(void)
     g_assert(!get_irq(FLOPPY_IRQ));
 }
 
+static uint8_t send_read_command(void)
+{
+    uint8_t drive = 0;
+    uint8_t head = 0;
+    uint8_t cyl = 0;
+    uint8_t sect_addr = 1;
+    uint8_t sect_size = 2;
+    uint8_t eot = 1;
+    uint8_t gap = 0x1b;
+    uint8_t gpl = 0xff;
+
+    uint8_t msr = 0;
+    uint8_t st0;
+
+    uint8_t ret = 0;
+
+    floppy_send(CMD_READ);
+    floppy_send(head << 2 | drive);
+    g_assert(!get_irq(FLOPPY_IRQ));
+    floppy_send(cyl);
+    floppy_send(head);
+    floppy_send(sect_addr);
+    floppy_send(sect_size);
+    floppy_send(eot);
+    floppy_send(gap);
+    floppy_send(gpl);
+
+    uint8_t i = 0;
+    uint8_t n = 2;
+    for (; i < n; i++) {
+        msr = inb(FLOPPY_BASE + reg_msr);
+        if (msr == 0xd0) {
+            break;
+        }
+        sleep(1);
+    }
+
+    if (i >= n) {
+        return 1;
+    }
+
+    st0 = floppy_recv();
+    if (st0 != 0x40) {
+        ret = 1;
+    }
+
+    floppy_recv();
+    floppy_recv();
+    floppy_recv();
+    floppy_recv();
+    floppy_recv();
+    floppy_recv();
+
+    return ret;
+}
+
 static void send_step_pulse(void)
 {
     int drive = 0;

@@ -146,6 +203,14 @@ static void test_no_media_on_start(void)
     assert_bit_set(dir, DSKCHG);
 }
 
+static void test_read_without_media(void)
+{
+    uint8_t ret;
+
+    ret = send_read_command();
+    g_assert(ret == 0);
+}
+
 static void test_media_change(void)
 {
     uint8_t dir;

@@ -214,6 +279,7 @@ int main(int argc, char **argv)
     qtest_irq_intercept_in(global_qtest, "ioapic");
     qtest_add_func("/fdc/cmos", test_cmos);
     qtest_add_func("/fdc/no_media_on_start", test_no_media_on_start);
+    qtest_add_func("/fdc/read_without_media", test_read_without_media);
     qtest_add_func("/fdc/media_change", test_media_change);
 
     ret = g_test_run();

index be35201..d338c3f 100644
@@ -153,8 +153,12 @@ static int fd_seek(FDrive *drv, uint8_t head, uint8_t track, uint8_t sect,
         }
 #endif
         drv->head = head;
-        if (drv->track != track)
+        if (drv->track != track) {
+            if (drv->bs != NULL && bdrv_is_inserted(drv->bs)) {
+                drv->media_changed = 0;
+            }
             ret = 1;
+        }
         drv->track = track;
         drv->sect = sect;
     }

@@ -170,9 +174,7 @@ static int fd_seek(FDrive *drv, uint8_t head, uint8_t track, uint8_t sect,
 static void fd_recalibrate(FDrive *drv)
 {
     FLOPPY_DPRINTF("recalibrate\n");
-    drv->head = 0;
-    drv->track = 0;
-    drv->sect = 1;
+    fd_seek(drv, 0, 0, 1, 1);
 }
 
 /* Revalidate a disk drive after a disk change */

@@ -711,14 +713,6 @@ static void fdctrl_raise_irq(FDCtrl *fdctrl, uint8_t status0)
         qemu_set_irq(fdctrl->irq, 1);
         fdctrl->sra |= FD_SRA_INTPEND;
     }
-    if (status0 & FD_SR0_SEEK) {
-        FDrive *cur_drv;
-        /* A seek clears the disk change line (if a disk is inserted) */
-        cur_drv = get_cur_drv(fdctrl);
-        if (cur_drv->bs != NULL && bdrv_is_inserted(cur_drv->bs)) {
-            cur_drv->media_changed = 0;
-        }
-    }
 
     fdctrl->reset_sensei = 0;
     fdctrl->status0 = status0;

@@ -1004,30 +998,39 @@ static int fdctrl_seek_to_next_sect(FDCtrl *fdctrl, FDrive *cur_drv)
                    fd_sector(cur_drv));
     /* XXX: cur_drv->sect >= cur_drv->last_sect should be an
        error in fact */
-    if (cur_drv->sect >= cur_drv->last_sect ||
-        cur_drv->sect == fdctrl->eot) {
-        cur_drv->sect = 1;
+    uint8_t new_head = cur_drv->head;
+    uint8_t new_track = cur_drv->track;
+    uint8_t new_sect = cur_drv->sect;
+
+    int ret = 1;
+
+    if (new_sect >= cur_drv->last_sect ||
+        new_sect == fdctrl->eot) {
+        new_sect = 1;
         if (FD_MULTI_TRACK(fdctrl->data_state)) {
-            if (cur_drv->head == 0 &&
+            if (new_head == 0 &&
                 (cur_drv->flags & FDISK_DBL_SIDES) != 0) {
-                cur_drv->head = 1;
+                new_head = 1;
             } else {
-                cur_drv->head = 0;
-                cur_drv->track++;
+                new_head = 0;
+                new_track++;
                 if ((cur_drv->flags & FDISK_DBL_SIDES) == 0)
-                    return 0;
+                    ret = 0;
             }
         } else {
-            cur_drv->track++;
-            return 0;
+            new_track++;
+            ret = 0;
         }
-        FLOPPY_DPRINTF("seek to next track (%d %02x %02x => %d)\n",
+        if (ret == 1) {
+            FLOPPY_DPRINTF("seek to next track (%d %02x %02x => %d)\n",
                        cur_drv->head, cur_drv->track,
                        cur_drv->sect, fd_sector(cur_drv));
+        }
     } else {
-        cur_drv->sect++;
+        new_sect++;
     }
-    return 1;
+    fd_seek(cur_drv, new_head, new_track, new_sect, 1);
+    return ret;
 }
 
 /* Callback for transfer end (stop or abort) */

@@ -1623,11 +1626,7 @@ static void fdctrl_handle_seek(FDCtrl *fdctrl, int direction)
     /* The seek command just sends step pulses to the drive and doesn't care if
      * there is a medium inserted of if it's banging the head against the drive.
      */
-    if (fdctrl->fifo[2] > cur_drv->max_track) {
-        cur_drv->track = cur_drv->max_track;
-    } else {
-        cur_drv->track = fdctrl->fifo[2];
-    }
+    fd_seek(cur_drv, cur_drv->head, fdctrl->fifo[2], cur_drv->sect, 1);
     /* Raise Interrupt */
     fdctrl_raise_irq(fdctrl, FD_SR0_SEEK);
 }

@@ -1692,9 +1691,10 @@ static void fdctrl_handle_relative_seek_out(FDCtrl *fdctrl, int direction)
     SET_CUR_DRV(fdctrl, fdctrl->fifo[1] & FD_DOR_SELMASK);
     cur_drv = get_cur_drv(fdctrl);
     if (fdctrl->fifo[2] + cur_drv->track >= cur_drv->max_track) {
-        cur_drv->track = cur_drv->max_track - 1;
+        fd_seek(cur_drv, cur_drv->head, cur_drv->max_track - 1,
+                cur_drv->sect, 1);
     } else {
-        cur_drv->track += fdctrl->fifo[2];
+        fd_seek(cur_drv, cur_drv->head, fdctrl->fifo[2], cur_drv->sect, 1);
     }
     fdctrl_reset_fifo(fdctrl);
     /* Raise Interrupt */

@@ -1708,9 +1708,9 @@ static void fdctrl_handle_relative_seek_in(FDCtrl *fdctrl, int direction)
     SET_CUR_DRV(fdctrl, fdctrl->fifo[1] & FD_DOR_SELMASK);
     cur_drv = get_cur_drv(fdctrl);
     if (fdctrl->fifo[2] > cur_drv->track) {
-        cur_drv->track = 0;
+        fd_seek(cur_drv, cur_drv->head, 0, cur_drv->sect, 1);
     } else {
-        cur_drv->track -= fdctrl->fifo[2];
+        fd_seek(cur_drv, cur_drv->head, fdctrl->fifo[2], cur_drv->sect, 1);
     }
     fdctrl_reset_fifo(fdctrl);
     /* Raise Interrupt */

index d338c3f..0a5d58d 100644
@@ -307,6 +307,9 @@ enum {
 };
 
 enum {
+    FD_SR0_DS0      = 0x01,
+    FD_SR0_DS1      = 0x02,
+    FD_SR0_HEAD     = 0x04,
     FD_SR0_EQPMT    = 0x10,
     FD_SR0_SEEK     = 0x20,
     FD_SR0_ABNTERM  = 0x40,

@@ -972,14 +975,15 @@ static void fdctrl_reset_fifo(FDCtrl *fdctrl)
 }
 
 /* Set FIFO status for the host to read */
-static void fdctrl_set_fifo(FDCtrl *fdctrl, int fifo_len, int do_irq)
+static void fdctrl_set_fifo(FDCtrl *fdctrl, int fifo_len, uint8_t status0)
 {
     fdctrl->data_dir = FD_DIR_READ;
     fdctrl->data_len = fifo_len;
     fdctrl->data_pos = 0;
     fdctrl->msr |= FD_MSR_CMDBUSY | FD_MSR_RQM | FD_MSR_DIO;
-    if (do_irq)
-        fdctrl_raise_irq(fdctrl, 0x00);
+    if (status0) {
+        fdctrl_raise_irq(fdctrl, status0);
+    }
 }
 
 /* Set an error: unimplemented/unknown command */

@@ -1040,10 +1044,12 @@ static void fdctrl_stop_transfer(FDCtrl *fdctrl, uint8_t status0,
     FDrive *cur_drv;
 
     cur_drv = get_cur_drv(fdctrl);
+    fdctrl->status0 = status0 | FD_SR0_SEEK | (cur_drv->head << 2) |
+                      GET_CUR_DRV(fdctrl);
+
     FLOPPY_DPRINTF("transfer status: %02x %02x %02x (%02x)\n",
-                   status0, status1, status2,
-                   status0 | (cur_drv->head << 2) | GET_CUR_DRV(fdctrl));
-    fdctrl->fifo[0] = status0 | (cur_drv->head << 2) | GET_CUR_DRV(fdctrl);
+                   status0, status1, status2, fdctrl->status0);
+    fdctrl->fifo[0] = fdctrl->status0;
     fdctrl->fifo[1] = status1;
     fdctrl->fifo[2] = status2;
     fdctrl->fifo[3] = cur_drv->track;

@@ -1056,7 +1062,7 @@ static void fdctrl_stop_transfer(FDCtrl *fdctrl, uint8_t status0,
     }
     fdctrl->msr |= FD_MSR_RQM | FD_MSR_DIO;
     fdctrl->msr &= ~FD_MSR_NONDMA;
-    fdctrl_set_fifo(fdctrl, 7, 1);
+    fdctrl_set_fifo(fdctrl, 7, fdctrl->status0);
 }
 
 /* Prepare a data transfer (either DMA or FIFO) */

@@ -1170,7 +1176,7 @@ static void fdctrl_start_transfer(FDCtrl *fdctrl, int direction)
     if (direction != FD_DIR_WRITE)
         fdctrl->msr |= FD_MSR_DIO;
     /* IO based transfer: calculate len */
-    fdctrl_raise_irq(fdctrl, 0x00);
+    fdctrl_raise_irq(fdctrl, FD_SR0_SEEK);
 
     return;
 }

@@ -1598,16 +1604,18 @@ static void fdctrl_handle_sense_interrupt_status(FDCtrl *fdctrl, int direction)
 {
     FDrive *cur_drv = get_cur_drv(fdctrl);
 
-    if(fdctrl->reset_sensei > 0) {
+    if (fdctrl->reset_sensei > 0) {
         fdctrl->fifo[0] =
             FD_SR0_RDYCHG + FD_RESET_SENSEI_COUNT - fdctrl->reset_sensei;
         fdctrl->reset_sensei--;
+    } else if (!(fdctrl->sra & FD_SRA_INTPEND)) {
+        fdctrl->fifo[0] = FD_SR0_INVCMD;
+        fdctrl_set_fifo(fdctrl, 1, 0);
+        return;
     } else {
-        /* XXX: status0 handling is broken for read/write
-           commands, so we do this hack. It should be suppressed
-           ASAP */
         fdctrl->fifo[0] =
-            FD_SR0_SEEK | (cur_drv->head << 2) | GET_CUR_DRV(fdctrl);
+                (fdctrl->status0 & ~(FD_SR0_HEAD | FD_SR0_DS1 | FD_SR0_DS0))
+                | GET_CUR_DRV(fdctrl);
     }
 
     fdctrl->fifo[1] = cur_drv->track;