source: xtideuniversalbios/trunk/Assembly_Library/Src/Time/TimerTicks.asm@ 89

Last change on this file since 89 was 85, checked in by Tomi Tilli, 14 years ago

Changes to Assembly Library:

  • Some minor adjustments
File size: 4.2 KB
RevLine 
[41]1; File name : TimerTicks.asm
2; Project name : Assembly Library
3; Created date : 24.7.2010
[60]4; Last update : 22.11.2010
[41]5; Author : Tomi Tilli
6; Description : Functions for system timer related operations.
7
8; System timer ticks 18.2 times per second = 54.9 ms / tick
9TICKS_PER_HOUR EQU 65520
10TICKS_PER_MINUTE EQU 1092
11TICKS_PER_SECOND EQU 18
12
13
14; Section containing code
15SECTION .text
16
17;--------------------------------------------------------------------
18; TimerTicks_GetHoursToAXfromTicksInDXAX
19; TimerTicks_GetMinutesToAXfromTicksInDX
20; TimerTicks_GetSecondsToAXfromTicksInDX
21; Parameters
22; DX(:AX): Timer ticks to convert
23; Returns:
24; AX: Hours, minutes or seconds
25; DX: Remainder ticks
26; Corrupts registers:
27; CX
28;--------------------------------------------------------------------
29ALIGN JUMP_ALIGN
30TimerTicks_GetHoursToAXfromTicksInDXAX:
31 mov cx, TICKS_PER_HOUR
32 div cx ; Divide DX:AX by CX, Hours to AX, remainder ticks to DX
33 ret
34
35ALIGN JUMP_ALIGN
36TimerTicks_GetMinutesToAXfromTicksInDX:
37 xor ax, ax
38 xchg ax, dx ; Ticks now in DX:AX
39 mov cx, TICKS_PER_MINUTE
40 div cx ; Divide DX:AX by CX, Minutes to AX, remainder ticks to DX
41 ret
42
43ALIGN JUMP_ALIGN
44TimerTicks_GetSecondsToAXfromTicksInDX:
45 xchg ax, dx ; Ticks now in AX
46 mov cl, TICKS_PER_SECOND
47 div cl ; Divide AX by CL, Seconds to AL, remainder ticks to AH
48 xor dx, dx
49 xchg dl, ah ; Seconds in AX, remainder in DX
50 ret
51
52
53;--------------------------------------------------------------------
54; First tick might take 0...54.9 ms and remaining ticks
55; will occur at 54.9 ms intervals. Use delay of two (or more) ticks to
56; ensure at least 54.9 ms timeout.
57;
58; TimerTicks_InitializeTimeoutFromAX
59; Parameters:
60; AX: Timeout ticks (54.9 ms) before timeout
61; DS:BX: Ptr to timeout variable WORD
62; Returns:
63; [DS:BX]: Initialized for TimerTicks_SetCarryIfTimeoutFromDSBX
64; Corrupts registers:
65; AX
66;--------------------------------------------------------------------
67ALIGN JUMP_ALIGN
68TimerTicks_InitializeTimeoutFromAX:
69 mov [bx], ax ; Store timeout ticks
70 call TimerTicks_ReadFromBdaToAX
71 add [bx], ax ; Add latest time to timeout ticks
72 ret
73
[60]74
[41]75;--------------------------------------------------------------------
[60]76; TimerTicks_GetTimeoutTicksLeftToAXfromDSBX
[41]77; Parameters:
78; DS:BX: Ptr to timeout variable WORD
79; Returns:
[85]80; AX: Number of ticks left before timeout
[41]81; CF: Set if timeout
82; Cleared if time left
83; Corrupts registers:
84; Nothing
85;--------------------------------------------------------------------
86ALIGN JUMP_ALIGN
[60]87TimerTicks_GetTimeoutTicksLeftToAXfromDSBX:
88 push dx
89 mov dx, [bx]
[41]90 call TimerTicks_ReadFromBdaToAX
[60]91 xchg ax, dx
92 sub ax, dx ; AX = End time - current time
93 pop dx
[41]94 ret
95
96
97;--------------------------------------------------------------------
98; TimerTicks_GetElapsedToAXandResetDSBX
99; Parameters
100; DS:BX: Ptr to WORD containing previous reset time
101; Returns:
102; AX: 54.9 ms ticks elapsed since last reset
103; [DS:BX]: Reset to latest time
104; Corrupts registers:
105; Nothing
106;--------------------------------------------------------------------
107ALIGN JUMP_ALIGN
108TimerTicks_GetElapsedToAXandResetDSBX:
109 call TimerTicks_ReadFromBdaToAX
110 push ax
111 sub ax, [bx]
112 pop WORD [bx] ; Latest time to [DS:BX]
113 ret
114
115;--------------------------------------------------------------------
116; TimerTicks_GetElapsedToAXfromDSBX
117; Parameters
118; DS:BX: Ptr to WORD containing previous update time
119; Returns:
120; AX: 54.9 ms ticks elapsed since initializing [DS:BX]
121; Corrupts registers:
122; Nothing
123;--------------------------------------------------------------------
124ALIGN JUMP_ALIGN
125TimerTicks_GetElapsedToAXfromDSBX:
126 call TimerTicks_ReadFromBdaToAX
127 sub ax, [bx]
128 ret
129
130
131;--------------------------------------------------------------------
132; TimerTicks_ReadFromBdaToAX
133; Parameters
134; Nothing
135; Returns:
136; AX: System time in 54.9 ms ticks
137; Corrupts registers:
138; Nothing
139;--------------------------------------------------------------------
140ALIGN JUMP_ALIGN
141TimerTicks_ReadFromBdaToAX:
142 push ds
143
144 LOAD_BDA_SEGMENT_TO ds, ax
145 mov ax, [BDA.dwTimerTicks] ; Read low WORD only
146
147 pop ds
148 ret
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