47 lines
1.1 KiB
C
47 lines
1.1 KiB
C
#ifndef GRUB_SPEAKER_HEADER
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#define GRUB_SPEAKER_HEADER 1
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#include <grub/cpu/io.h>
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#include <grub/i386/pit.h>
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/* The frequency of the PIT clock. */
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#define GRUB_SPEAKER_PIT_FREQUENCY 0x1234dd
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static inline void
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grub_speaker_beep_off (void)
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{
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unsigned char status;
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status = grub_inb (GRUB_PIT_SPEAKER_PORT);
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grub_outb (status & ~(GRUB_PIT_SPK_TMR2 | GRUB_PIT_SPK_DATA),
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GRUB_PIT_SPEAKER_PORT);
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}
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static inline void
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grub_speaker_beep_on (grub_uint16_t pitch)
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{
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unsigned char status;
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unsigned int counter;
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if (pitch < 20)
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pitch = 20;
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else if (pitch > 20000)
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pitch = 20000;
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counter = GRUB_SPEAKER_PIT_FREQUENCY / pitch;
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/* Program timer 2. */
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grub_outb (GRUB_PIT_CTRL_SELECT_2
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| GRUB_PIT_CTRL_READLOAD_WORD
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| GRUB_PIT_CTRL_SQUAREWAVE_GEN
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| GRUB_PIT_CTRL_COUNT_BINARY, GRUB_PIT_CTRL);
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grub_outb (counter & 0xff, GRUB_PIT_COUNTER_2); /* LSB */
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grub_outb ((counter >> 8) & 0xff, GRUB_PIT_COUNTER_2); /* MSB */
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/* Start speaker. */
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status = grub_inb (GRUB_PIT_SPEAKER_PORT);
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grub_outb (status | GRUB_PIT_SPK_TMR2 | GRUB_PIT_SPK_DATA,
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GRUB_PIT_SPEAKER_PORT);
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}
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#endif
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