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https://github.com/reactos/reactos.git
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116 lines
3.4 KiB
C
116 lines
3.4 KiB
C
/*
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* PROJECT: ReactOS HAL
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* LICENSE: BSD - See COPYING.ARM in the top level directory
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* FILE: hal/halx86/generic/beep.c
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* PURPOSE: Speaker support (beeping)
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* PROGRAMMERS: ReactOS Portable Systems Group
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*/
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/* INCLUDES ******************************************************************/
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#include <hal.h>
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#define NDEBUG
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#include <debug.h>
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/* FUNCTIONS *****************************************************************/
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/*
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* @implemented
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*/
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BOOLEAN
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NTAPI
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HalMakeBeep(IN ULONG Frequency)
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{
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SYSTEM_CONTROL_PORT_B_REGISTER SystemControl;
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TIMER_CONTROL_PORT_REGISTER TimerControl;
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ULONG Divider;
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BOOLEAN Result = FALSE;
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//
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// Acquire CMOS Lock
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//
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HalpAcquireSystemHardwareSpinLock();
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//
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// Turn the timer off by disconnecting its output pin and speaker gate
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//
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SystemControl.Bits = __inbyte(SYSTEM_CONTROL_PORT_B);
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SystemControl.SpeakerDataEnable = FALSE;
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SystemControl.Timer2GateToSpeaker = FALSE;
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__outbyte(SYSTEM_CONTROL_PORT_B, SystemControl.Bits);
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//
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// Check if we have a frequency
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//
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if (Frequency)
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{
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//
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// Set the divider
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//
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Divider = PIT_FREQUENCY / Frequency;
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//
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// Check if it's too large
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//
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if (Divider <= 0x10000)
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{
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//
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// Program the PIT for binary mode
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//
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TimerControl.BcdMode = FALSE;
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//
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// Program the PIT to generate a square wave (Mode 3) on channel 2.
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// Channel 0 is used for the IRQ0 clock interval timer, and channel
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// 1 is used for DRAM refresh.
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//
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// Mode 2 gives much better accuracy, but generates an output signal
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// that drops to low for each input signal cycle at 0.8381 useconds.
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// This is too fast for the PC speaker to process and would result
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// in no sound being emitted.
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//
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// Mode 3 will generate a high pulse that is a bit longer and will
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// allow the PC speaker to notice. Additionally, take note that on
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// channel 2, when input goes low the counter will stop and output
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// will go to high.
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//
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TimerControl.OperatingMode = PitOperatingMode3;
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TimerControl.Channel = PitChannel2;
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//
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// Set the access mode that we'll use to program the reload value.
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//
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TimerControl.AccessMode = PitAccessModeLowHigh;
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//
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// Now write the programming bits
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//
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__outbyte(TIMER_CONTROL_PORT, TimerControl.Bits);
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//
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// Next we write the reload value for channel 2
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//
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__outbyte(TIMER_CHANNEL2_DATA_PORT, Divider & 0xFF);
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__outbyte(TIMER_CHANNEL2_DATA_PORT, Divider >> 8);
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//
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// Reconnect the speaker to the timer and re-enable the output pin
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//
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SystemControl.Bits = __inbyte(SYSTEM_CONTROL_PORT_B);
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SystemControl.SpeakerDataEnable = TRUE;
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SystemControl.Timer2GateToSpeaker = TRUE;
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__outbyte(SYSTEM_CONTROL_PORT_B, SystemControl.Bits);
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Result = TRUE;
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}
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}
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//
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// Release CMOS lock
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//
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HalpReleaseCmosSpinLock();
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//
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// Return success
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//
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return Result;
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}
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