Changeset 258 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CreateDPT.asm

Timestamp:

Feb 22, 2012, 7:01:53 PM (13 years ago)

Author:

gregli@…

google:author:

gregli@hotmail.com

Message:

Added floppy drive emulation over the serial connection (MODULE_SERIAL_FLOPPY). Along the way, various optimizations were made to stay within the 8K ROM size target. Also, serial code now returns the number of sectors transferred.

File:

• trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CreateDPT.asm (modified) (3 diffs)

trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/CreateDPT.asm

@@ -63 +63 @@
 .StoreFlags:
     mov     [di+DPT.wFlags], ax
-
-%ifdef MODULE_SERIAL
-    cmp     byte [cs:bp+IDEVARS.bDevice], DEVICE_SERIAL_PORT
-    jnz     .StoreAddressing
-    or      byte [di+DPT.bFlagsHigh], FLGH_DPT_SERIAL_DEVICE
-%endif
     ; Fall to .StoreAddressing
 
@@ -205 +199 @@
 .StoreDeviceSpecificParameters:
     call    Device_FinalizeDPT
+
+%ifdef MODULE_SERIAL_FLOPPY
+;
+; These two instructions serve two purposes:
+; 1. If the drive is a floppy drive (CF set), then we effectively increment the counter.
+; 2. If this is a hard disk, and there have been any floppy drives previously added, then the hard disk is 
+;    effectively discarded.  This is more of a safety check then code that should ever normally be hit (see below).
+;    Since the floppy DPT's come after the hard disk DPT's, without expensive (code size) code to relocate a DPT, 
+;    this was necessary.  Now, this situation shouldn't happen in normal operation, for a couple of reasons:
+;       A. xtidecfg always puts configured serial ports at the end fo the IDEVARS list
+;       B. the auto serial code is always executed last
+;       C. the serial server always returns floppy drives last
+;
+    adc     byte [RAMVARS.xlateVars+XLATEVARS.bFlopCreateCnt], 0
+    jnz     .AllDone    
+%else
+;
+; Even without floppy support enabled, we shouldn't try to mount a floppy image as a hard disk, which
+; could lead to unpredictable results since no MBR will be present, etc.  The server doesn't know that 
+; floppies are supported, so it is important to still fail here if a floppy is seen during the drive scan.
+;
+    jc      .AllDone
+%endif
+
     ; Fall to .StoreDriveNumberAndUpdateDriveCount
 
@@ -230 +248 @@
     ja      SHORT .AllDone              ;  If so, return
     mov     [RAMVARS.bFirstDrv], dl     ; Store first drive number
+
+.AllDone:
     clc
-.AllDone:
     ret
+