Changeset 84 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h.asm

Timestamp:

Jan 14, 2011, 10:57:46 PM (13 years ago)

Author:

krille_n_@…

google:author:

krille_n_@hotmail.com

Message:

Minor size optimizations in various files.

File:

• trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h.asm (modified) (2 diffs)

trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h.asm

@@ -2 +2 @@
 ; Project name  :   IDE BIOS
 ; Created date  :   21.9.2007
-; Last update   :   24.8.2010
-; Author        :   Tomi Tilli
+; Last update   :   14.1.2011
+; Author        :   Tomi Tilli,
+;               :   Krister Nordvall (optimizations)
 ; Description   :   Int 13h BIOS functions (Floppy and Hard disk).
 
@@ -63 +64 @@
     ja      SHORT Int13h_UnsupportedFunction
     mov     di, ax
+%ifndef USE_186 ; This uses 9 bytes less and is about 5 cycles faster
+    mov     al, ah                      ; Copy bits in AH to AL and then
+    shl     al, 1                       ; shift them "back" 1 step
+    and     al, 7Eh                     ; AND them (clears the MSB)
+    cbw                                 ; Clear AH using sign extension
+    xchg    di, ax                      ; and finally swap DI with AX
+%else
     eSHR_IM di, 7                       ; Shift function to DI...
     and     di, BYTE 7Eh                ; ...and prepare for word lookup
+%endif
     jmp     [cs:di+g_rgw13hFuncJump]    ; Jump to BIOS function