Changeset 52 in xtideuniversalbios for trunk/Assembly_Library/Src/Display/CgaSnow.asm

Timestamp:

Oct 12, 2010, 6:51:07 PM (15 years ago)

Author:

Tomi Tilli

google:author:

aitotat

Message:

Changes to Assembly Library:
Completely rewritten line splitting (slower but no need to modify string).
Some changes to string processing functions.
Saved few bytes from CGA detection.

File:

• trunk/Assembly_Library/Src/Display/CgaSnow.asm (modified) (3 diffs)

trunk/Assembly_Library/Src/Display/CgaSnow.asm

@@ -2 +2 @@
 ; Project name  :   Assembly Library
 ; Created date  :   8.10.2010
-; Last update   :   9.10.2010
+; Last update   :   12.10.2010
 ; Author        :   Tomi Tilli
 ; Description   :   Functions for preventing CGA snow.
@@ -23 +23 @@
     cmp     WORD [BDA.wVidPort], CGA_STATUS_REGISTER - OFFSET_TO_CGA_STATUS_REGISTER
     jne     SHORT .CgaNotFound
-    call    DisplayPage_GetColumnsToALandRowsToAH
-    cmp     ah, [BDA.bVidRows]      ; Video rows stored only by EGA and later
-    je      SHORT .CgaNotFound      ; Must be EGA or later
+
+    ; All standard CGA modes use 25 rows but only EGA and later store it to BDA.
+    cmp     BYTE [BDA.bVidRows], 25
+    jge     SHORT .CgaNotFound
     stc
     ret
@@ -83 +84 @@
 
 ;--------------------------------------------------------------------
-; CgaSnow_Scasb
-;   Parameters:
-;       AL:     Byte for comparison
-;       DS:     BDA segment (zero)
-;       ES:DI:  Ptr to video memory where to output
-;   Returns:
-;       DI:     Incremented for next character
-;   Corrupts registers:
-;       AX, DX
-;--------------------------------------------------------------------
-ALIGN JUMP_ALIGN
-CgaSnow_Scasb:
-    call    LoadCgaStatusRegisterAddressToDXifCgaPresent
-    jz      SHORT .ScasbWithoutWaitSinceUnknownPort
-
-    mov     ah, al
-    cli             ; Interrupt request would mess up timing
-    WAIT_UNTIL_SAFE_CGA_WRITE
-    mov     al, ah
-.ScasbWithoutWaitSinceUnknownPort:
-    scasb
-    sti
-    ret
-
-
-;--------------------------------------------------------------------
 ; CgaSnow_RepMovsb
 ;   Parameters: