79 lines
2.3 KiB
NASM
79 lines
2.3 KiB
NASM
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SECTION .text
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USE16
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initialize:
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.fpu: ;enable fpu
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mov eax, cr0
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and al, 11110011b
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or al, 00100010b
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mov cr0, eax
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mov eax, cr4
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or eax, 0x200
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mov cr4, eax
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fninit
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ret
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.sse: ;enable sse
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mov eax, cr4
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or ax, 0000011000000000b
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mov cr4, eax
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ret
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;PIT Frequency
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;If using nanoseconds, to minimize drift, one should find a frequency as close to an integer nanosecond value in wavelength
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;Divider Hz Nanoseconds Properties
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;2685 444.38795779019242706393 2250286.00003631746492922946 Best For Context Switching
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;5370 222.19397889509621353196 4500572.00007263492985856020
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;21029 56.73981961418358774390 17624306.99991199998882825455
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;23714 50.31549576902532962244 19874592.99994831745375667118
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;26399 45.19798729749864262535 22124878.99998463491868476373
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;29084 41.02536331545408701233 24375165.00002095238361424615
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;31769 37.55804925136663623868 26625451.00005726984854313455
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;34454 34.63115071302799868423 28875737.00009358731347639618
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;50113 23.80982313305263437963 41999471.99993295237244784676
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;52798 22.59899364874932131267 44249757.99996926983737931766
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;55483 21.50535599492937776736 46500044.00000558730230583335 Lowest Drift
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;58168 20.51268165772704350616 48750330.00004190476724037528
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;60853 19.60760630809765610021 51000616.00007822223218031738
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.pit:
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;initialize the PIT
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mov ax, 5370 ;this is the divider for the PIT
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out 0x40, al
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rol ax, 8
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out 0x40, al
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;DISABLED ;enable rtc interrupt
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;mov al, 0xB
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;out 0x70, al
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;rol ax, 8
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;in al, 0x71
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;rol ax, 8
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;out 0x70, al
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;rol ax, 8
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;or al, 0x40
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;out 0x71, al
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ret
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.pic: ;sets up IRQs at int 20-2F
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mov al, 0x11
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out 0x20, al
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out 0xA0, al
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mov al, 0x20 ;IRQ0 vector
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out 0x21, al
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mov al, 0x28 ;IRQ8 vector
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out 0xA1, al
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mov al, 4
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out 0x21, al
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mov al, 2
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out 0xA1, al
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mov al, 1
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out 0x21, al
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out 0xA1, al
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xor al, al ;no IRQ masks
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out 0x21, al
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out 0xA1, al
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mov al, 0x20 ;reset PIC's
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out 0xA0, al
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out 0x20, al
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ret
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