2011-04-12 23:43:22 +00:00
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#include "x16.h"
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#undef ORB
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TEXT a20(SB), $0
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CALL rmode16(SB)
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2011-04-20 10:49:54 +00:00
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CALL16(spllo(SB))
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2011-04-12 23:43:22 +00:00
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LWI(0x2401, rAX)
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BIOSCALL(0x15)
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JC _biosfail
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CALL16(pmode32(SB))
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RET
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_biosfail:
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CALL16(pmode32(SB))
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2011-04-20 13:19:06 +00:00
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/* fast a20 */
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MOVL $0x92, DX
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INB
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ANDB $0xFE, AX
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ORB $0x02, AX
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OUTB
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/* slow a20 */
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2011-04-12 23:43:22 +00:00
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CALL a20wait(SB)
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MOVL $0x64, DX
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MOVB $0xAD, AL
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OUTB
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CALL a20wait(SB)
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MOVL $0x64, DX
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MOVB $0xD0, AL
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OUTB
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CALL a20wait2(SB)
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MOVL $0x60, DX
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INB
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PUSHL AX
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CALL a20wait(SB)
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MOVL $0x64, DX
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MOVB $0xD1, AL
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OUTB
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CALL a20wait(SB)
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MOVL $0x60, DX
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POPL AX
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ORB $2, AL
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OUTB
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CALL a20wait(SB)
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MOVL $0x64, DX
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MOVB $0xAE, AL
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OUTB
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TEXT a20wait(SB), $0
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_a20wait:
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MOVL $0x64, DX
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INB
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TESTB $1, AL
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JZ _a20wait2
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RET
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TEXT a20wait2(SB), $0
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_a20wait2:
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MOVL $0x64, DX
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INB
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TESTB $2, AL
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JNZ _a20wait
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RET
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