Changeset 258 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Initialization/DetectDrives.asm

Timestamp:

Feb 22, 2012, 7:01:53 PM (12 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/Initialization/DetectDrives.asm (modified) (2 diffs)

trunk/XTIDE_Universal_BIOS/Src/Initialization/DetectDrives.asm

@@ -43 +43 @@
 
 %ifdef MODULE_SERIAL
+;----------------------------------------------------------------------
 ;
 ; if serial drive detected, do not scan (avoids duplicate drives and isn't needed - we already have a connection)
@@ -57 +58 @@
 %endif
 
-.done:
+.done:  
+%ifdef MODULE_SERIAL_FLOPPY
+;----------------------------------------------------------------------
+;
+; Add in any emulated serial floppy drives.
+;
+    mov     al, [RAMVARS.xlateVars+XLATEVARS.bFlopCreateCnt]
+    dec     al
+    mov     cl, al
+    js      .NoFloppies                     ; if no drives are present, we store 0ffh
+
+    call    FloppyDrive_GetCountFromBIOS_or_BDA
+
+    push    ax
+
+    add     al, cl                          ; Add our drives to existing drive count
+    cmp     al, 3                           ; For BDA, max out at 4 drives (ours is zero based)
+    jl      .MaxBDAFloppiesExceeded
+    mov     al, 3                           
+.MaxBDAFloppiesExceeded:
+    eROR_IM al, 2                           ; move to bits 6-7
+    inc     ax                              ; low order bit, indicating floppy drive exists
+
+    mov     ah, [es:BDA.wEquipment]         ; Load Equipment WORD low byte  
+    and     ah, 03eh                        ; Mask off drive number and drives present bit
+    or      al, ah                          ; Or in new values
+    mov     [es:BDA.wEquipment], al         ; and store
+
+    mov     al, 1eh                         ; BDA pointer to Floppy DPT
+    mov     si, AH8h_FloppyDPT
+    call    Interrupts_InstallHandlerToVectorInALFromCSSI
+
+    pop     ax
+
+    shr     cl, 1                           ; number of drives, 1 or 2 only, to CF flag (clear=1, set=2)
+    rcl     al, 1                           ; starting drive number in upper 7 bits, number of drives in low bit
+.NoFloppies:    
+    mov     [RAMVARS.xlateVars+XLATEVARS.bFlopCntAndFirst], al
+%endif
+        
     ret