2024-07-14 13:11:28 +00:00
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;; File: pit.inc
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;;
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;; Usefull links:
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;; - <http://www.osdever.net/bkerndev/Docs/pit.htm>
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PIT_CHANNEL0 = 0x40
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PIT_CHANNEL1 = 0x40
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PIT_CHANNEL2 = 0x42
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PIT_COMMAND = 0x43
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2024-07-28 09:09:24 +00:00
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PIT_MAX_FREQ = 1193180
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2024-07-14 13:11:28 +00:00
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;; Function: pit_init
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2024-07-28 09:09:24 +00:00
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;;
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;; In:
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;; AX - freq
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2024-07-14 13:11:28 +00:00
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pit_init:
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2024-07-28 09:09:24 +00:00
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movzx eax, ax
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xor edx, edx
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mov ecx, PIT_MAX_FREQ
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div ecx
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push eax
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mov dx, PIT_COMMAND
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mov al, 0x34 ;channel 0, lobyte/hibyte, rate generator
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pop eax
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mov dx, PIT_CHANNEL0
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out dx, al
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xchg al, ah
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out dx, al
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2024-07-14 13:11:28 +00:00
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ret
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;; Function: pit_irq
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pit_irq:
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pusha
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;mov esi, szMsgPitIRQ
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;call klog
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mov al, PIC_EOI
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out PIC1_COMMAND, al
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popa
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iret
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szMsgPitIRQ db "PIT: IRQ", 0
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