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NAME
- ReadExpansionByte
-
read a byte nybble by nybble.
SYNOPSIS
byte = ReadExpansionByte( board, offset )
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FUNCTION
(Not typically called by user code)
ReadExpansionByte reads a byte from a new-style expansion board. These boards have their readable data organized as a series of nybbles in memory. This routine reads two nybbles and returns the byte value.
In general, this routine will only be called by ReadExpansionRom.
The offset is a byte offset, as if into a ExpansionRom structure. The actual memory address read will be four times larger. The macros EROFFSET and ECOFFSET are provided to help get these offsets from C.
ReadExpansionByte reads a byte from a new-style expansion board. These boards have their readable data organized as a series of nybbles in memory. This routine reads two nybbles and returns the byte value.
In general, this routine will only be called by ReadExpansionRom.
The offset is a byte offset, as if into a ExpansionRom structure. The actual memory address read will be four times larger. The macros EROFFSET and ECOFFSET are provided to help get these offsets from C.
INPUTS
- board
-
a pointer to the base of a new style expansion board.
- offset
-
a logical offset from the board base
RESULT
- byte
-
a byte of data from the expansion board.
EXAMPLE
byte = ReadExpansionByte( cd->BoardAddr, EROFFSET( er_Type ) );
ints = ReadExpansionByte( cd->BoardAddr, ECOFFSET( ec_Interrupt ) );
ints = ReadExpansionByte( cd->BoardAddr, ECOFFSET( ec_Interrupt ) );