source: xtideuniversalbios/trunk/Assembly_Library/Inc/SystemTimer.inc@ 268

; Project name  :   Assembly Library
; Description   :   System Timer (8254) relates equates and macros.
%ifndef SYSTEMTIMER_INC
%define SYSTEMTIMER_INC

; Timer/Counter to program
TIMER_0                                 EQU (0<<6)
TIMER_1                                 EQU (1<<6)
TIMER_2                                 EQU (2<<6)

; Counter commands
LATCH                                   EQU (0<<4)  ; Counter Latch Command (latches the count for reading)
READ_OR_WRITE_LSB_ONLY                  EQU (1<<4)  ; MSB is always zero
READ_OR_WRITE_MSB_ONLY                  EQU (2<<4)  ; LSB is always zero
READ_OR_WRITE_LSB_THEN_MSB              EQU (3<<4)

; Timer modes
MODE_0_SINGLE_TIMEOUT                   EQU (0<<1)  ; Interrupt on Terminal Count
MODE_1_ONE_SHOT                         EQU (1<<1)  ; Hardware Retriggerable One-Shot
MODE_2_RATE_GENERATOR                   EQU (2<<1)
MODE_3_SQUARE_WAVE_MODE                 EQU (3<<1)
MODE_4_SOFTWARE_TRIGGERED_STROBE        EQU (4<<1)
MODE_5_HARDWARE_RETRIGGERABLE_STROBE    EQU (5<<1)

; Binary / BCD Mode
BINARY_COUNTER                          EQU 0
BCD_COUNTER                             EQU 1


; Ports
COUNT_REGISTER_0                        EQU 40h     ; Timer 0 Count Register (System Timer Ticks)
COUNT_REGISTER_1                        EQU 41h     ; Timer 1 Count Register (DRAM Refresh)
COUNT_REGISTER_2                        EQU 42h     ; Timer 2 Count Register (General Use)
CONTROL_WORD_REGISTER_out               EQU 43h

; Timer 2 is Connected to PC Speaker that can be controller from port 61h.
SPEAKER_CONTROL_REGISTER                EQU 61h
FLG_TIMER_2_OUTPUT_in                   EQU (1<<5)  ; AT+ only
FLG_SPEAKER_DATA_ENABLED                EQU (1<<1)
FLG_SPEAKER_GATE_TIMER_2_ON             EQU (1<<0)


; The duration of one tick
TIMER_CYCLE_TIME                        EQU 838     ; nanosecs




;--------------------------------------------------------------------
; OUTPUT_COUNTER_COMMAND_TO
;   Parameters:
;       %1:     TIMER_0, TIMER_1 or TIMER_2
;       %2:     Command to counter
;       %3:     Timer mode
;       %4:     BINARY_COUNTER or BCD_COUNTER
;   Returns:
;       Nothing
;   Corrupts registers:
;       AL
;--------------------------------------------------------------------
%macro OUTPUT_COUNTER_COMMAND_TO 4
    mov     al, %1 | %2 | %3 | %4
    out     CONTROL_WORD_REGISTER_out, al
%endmacro


;--------------------------------------------------------------------
; WRITE_COUNT_FROM_AL_TO
; WRITE_COUNT_FROM_AX_TO
;   Parameters:
;       %1:     TIMER_0, TIMER_1 or TIMER_2
;       AX:     Count to write to timer
;   Returns:
;       Nothing
;   Corrupts registers:
;       AL (WRITE_COUNT_FROM_AX_TO only)
;--------------------------------------------------------------------
%macro WRITE_COUNT_FROM_AL_TO 1
    %ifidni %1, TIMER_0
        out     COUNT_REGISTER_0, al
    %elifidni %1, TIMER_1
        out     COUNT_REGISTER_1, al
    %elifidni %1, TIMER_2
        out     COUNT_REGISTER_2, al
    %else
        %error "Invalid timer name passed to WRITE_COUNT_FROM_AL_TO"
    %endif
%endmacro

%macro WRITE_COUNT_FROM_AX_TO 1
    %ifidni %1, TIMER_0
        out     COUNT_REGISTER_0, al
        mov     al, ah
        out     COUNT_REGISTER_0, al
    %elifidni %1, TIMER_1
        out     COUNT_REGISTER_1, al
        mov     al, ah
        out     COUNT_REGISTER_1, al
    %elifidni %1, TIMER_2
        out     COUNT_REGISTER_2, al
        mov     al, ah
        out     COUNT_REGISTER_2, al
    %else
        %error "Invalid timer name passed to WRITE_COUNT_FROM_AX_TO"
    %endif
%endmacro


;--------------------------------------------------------------------
; READ_COUNT_TO_AL_FROM
; READ_COUNT_TO_AX_FROM
;   Parameters:
;       %1:     TIMER_0, TIMER_1 or TIMER_2
;   Returns:
;       AL/AX:  Counter value
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%macro READ_COUNT_TO_AL_FROM 1
    %ifidni %1, TIMER_0
        in      al, COUNT_REGISTER_0
    %elifidni %1, TIMER_1
        in      al, COUNT_REGISTER_1
    %elifidni %1, TIMER_2
        in      al, COUNT_REGISTER_2
    %else
        %error "Invalid timer name passed to READ_COUNT_TO_AL_FROM"
    %endif
%endmacro

%macro READ_COUNT_TO_AX_FROM 1
    %ifidni %1, TIMER_0
        in      al, COUNT_REGISTER_0
        mov     ah, al
        in      al, COUNT_REGISTER_0
    %elifidni %1, TIMER_1
        in      al, COUNT_REGISTER_1
        mov     ah, al
        in      al, COUNT_REGISTER_1
    %elifidni %1, TIMER_2
        in      al, COUNT_REGISTER_2
        mov     ah, al
        in      al, COUNT_REGISTER_2
    %else
        %error "Invalid timer name passed to READ_COUNT_TO_AX_FROM"
    %endif
        xchg    al, ah
%endmacro


;--------------------------------------------------------------------
; START_PRECISE_EVENT_TIMER
;   Parameters:
;       Nothing
;   Returns:
;       Nothing
;   Corrupts registers:
;       AL
;--------------------------------------------------------------------
%macro START_PRECISE_EVENT_TIMER 0
    in      al, SPEAKER_CONTROL_REGISTER
    or      al, FLG_SPEAKER_GATE_TIMER_2_ON
    out     SPEAKER_CONTROL_REGISTER, al
%endmacro


;--------------------------------------------------------------------
; STOP_PRECISE_EVENT_TIMER
;   Parameters:
;       Nothing
;   Returns:
;       Nothing
;   Corrupts registers:
;       AL
;--------------------------------------------------------------------
%macro STOP_PRECISE_EVENT_TIMER 0
    in      al, SPEAKER_CONTROL_REGISTER
    and     al, ~(FLG_SPEAKER_DATA_ENABLED | FLG_SPEAKER_GATE_TIMER_2_ON)
    out     SPEAKER_CONTROL_REGISTER, al
%endmacro


%endif ; SYSTEMTIMER_INC