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NAME
- AllocExpansionMem
-
allocate expansion memory
SYNOPSIS
startSlot = AllocExpansionMem( numSlots, slotOffset )
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FUNCTION
(Not typically called by user code)
This function allocates numslots of expansion space (each slot is E_SLOTSIZE bytes). It returns the slot number of the start of the expansion memory. The EC_MEMADDR macro may be used to convert this to a memory address.
Boards that fit the expansion architecture have alignment rules. Normally a board must be on a binary boundary of its size. Four and Eight megabyte boards have special rules. User defined boards might have other special rules.
If AllocExpansionMem() succeeds, the startSlot will satisfy the following equation:
This function allocates numslots of expansion space (each slot is E_SLOTSIZE bytes). It returns the slot number of the start of the expansion memory. The EC_MEMADDR macro may be used to convert this to a memory address.
Boards that fit the expansion architecture have alignment rules. Normally a board must be on a binary boundary of its size. Four and Eight megabyte boards have special rules. User defined boards might have other special rules.
If AllocExpansionMem() succeeds, the startSlot will satisfy the following equation:
(startSlot - slotOffset) MOD slotAlign = 0
INPUTS
- numSlots
-
the number of slots required.
- slotOffset
-
an offset from that boundary for startSlot.
RESULT
- startSlot
-
the slot number that was allocated, or -1 for error.
EXAMPLE
AllocExpansionMem( 2, 0 )
Tries to allocate 2 slots on a two slot boundary.
This is the allocation rule for 4 meg boards. It allocates
4 megabytes (64 slots) on an odd 2 meg boundary.
AllocExpansionMem( 64, 32 )
4 megabytes (64 slots) on an odd 2 meg boundary.