24 lines
643 B
C
24 lines
643 B
C
#ifndef A20_H_
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#define A20_H_
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/*
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* FAST_A20_GATE - I/O port used to read the state of the a20 line and to
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* enable it if needed.
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*
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* A20_ENABLED_BIT - This value can be tested to check if the a20 line is
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* enabled, if we want to enable it just OR the value read from the I/O
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* port with A20_ENABLED_BIT and write the new value back in the port.
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*
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* FAST_RESET_MASK - It is important to unset the first bit of the byte
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* written back in the port because it causes a fast reset, this is
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* undesired when enabling the a20 line.
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*
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*/
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#define FAST_A20_GATE 0x92
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#define A20_ENABLED_BIT 0x02
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#define FAST_RESET_MASK 0x01
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#endif
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