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From: James Courtier-Dutton <James@superbug.co.uk>
To: linux-msdos@vger.kernel.org
Subject: [Patch]  Fix DOS get time function.
Date: Fri, 16 Nov 2007 02:56:32 +0000	[thread overview]
Message-ID: <473D06E0.1030507@superbug.co.uk> (raw)

[-- Attachment #1: Type: text/plain, Size: 281 bytes --]

Hi,

The current DOS INT 21 AH=2C  get time function returns incorrect 
results, and is sometimes hours off.
The attached patch fixes the problem.
It should patch against DOSBOX 0.72
the (X * 500 / 91)  is the same as  X * 100 / 18.2


Signed-off-by:  James@superbug.co.uk

James


[-- Attachment #2: time-fix.diff --]
[-- Type: text/x-patch, Size: 561 bytes --]

--- src/dos/dos.cpp.org	2007-11-16 02:46:35.000000000 +0000
+++ src/dos/dos.cpp	2007-11-16 02:54:50.000000000 +0000
@@ -348,8 +348,9 @@
 //TODO Get time through bios calls date is fixed
 		{
 /*	Calculate how many miliseconds have passed */
-			Bitu ticks=5*mem_readd(BIOS_TIMER);
-			ticks = ((ticks / 59659u) << 16) + ((ticks % 59659u) << 16) / 59659u;
+			/* seconds = ticks / 18.2 */
+			Bitu ticks=500 * mem_readd(BIOS_TIMER);
+			ticks = ticks / 91;
 			Bitu seconds=(ticks/100);
 			reg_ch=(Bit8u)(seconds/3600);
 			reg_cl=(Bit8u)((seconds % 3600)/60);

             reply	other threads:[~2007-11-16  2:56 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-11-16  2:56 James Courtier-Dutton [this message]
2007-11-19 22:44 ` [Patch] Fix DOS get time function Bart Oldeman

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