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id: @(#)allocator.fth 1.2 98/03/24
copyright: Copyright 1998 Sun Microsystems, Inc. All Rights Reserved
\ XXX This is a crude brute-force allocation scheme that won't work for
\ many cases, but probably will work for most of the situations we will
\ face in practise -- a prototype version that gets lots of memory once,
\ releases it once, and while the host adaptor is active, parcels out bits
-1 value dma-base \ Must be global
-1 value dev-dma-base \ Ditto
h# 10.0000 constant #grab
#grab dma-alloc to dma-base
dma-base #grab false dma-map-in to dev-dma-base
dma-base dev-dma-base #grab dma-map-out
dma-base dev-dma-base #grab dma-sync
: virt>offset ( virt -- offset ) dma-base - ;
: dev>offset ( dev -- offset ) dev-dma-base - ;
: offset>virt ( offset -- virt ) dma-base + ;
: offset>dev ( offset -- dev ) dev-dma-base + ;
: virt>dev ( virt -- dev ) virt>offset offset>dev ;
: dev>virt ( dev -- virt ) dev>offset offset>virt ;
\ XXX alignment restrictions. first fit. keep list in sorted order. key
\ on virt address. keep actual requested amount and allocated amount for
\ now. do in 1k byte chunks for now. this gives 1000 entries for 1000
\ pieces to get to 1 meg grabbed in the first place.
\ most alignment can actually be done to 32 bytes.
\ The allocation table has one entry for each chunk of the dma space.
\ So, 1k entries * 1kbytes/entry = 1meg. The entry is marked if that
\ chunk is allocated. It is unmarked if that chunk is available. This
\ gives coalescing chunks for free.
\ The memory must be like dma-alloc and dma-free -- the requester must free
\ exactly what it asked for.
/n field >marker \ non-zero if allocated
/n field >caller-addr \ in case this is a copy buffer
h# 400 constant /slot \ #bytes for each table slot
#grab /slot / constant #mem-entries
#mem-entries /entry * buffer: mem-table
\ In case the table representation changes, use these:
: mark ( tbl-addr #slots -- )
: unmark ( tbl-addr #slots -- )
: slot>tbl-addr ( slot# -- table-addr ) /entry * mem-table + ;
: marked? ( slot# -- marker ) slot>tbl-addr >marker @ ;
: virt>slot ( virt -- slot# ) virt>offset /slot / ;
: slot>virt ( slot# -- virt ) /slot * dma-base + ;
: #slots ( #bytes -- #slots-taken ) \ number of slots for this many bytes
\ slot#1 is the start slot. slot#2 is the first slot that is unmarked.
\ There had better be one, or this will fail. slot#2 could = slot#1
\ could use left-parse-string
: find-next-open ( slot#1 -- slot#2 )
dup #mem-entries swap - 0 do
\ could fill a region of memory w. 0's and do successive compares
\ XXX again, there had better be a chunk that works somewhere in the table
: enough-slots? ( slot# #slots-needed -- yes? )
dup i + marked? if nip false swap leave then
\ XXX this is dumb. brute force. slows down in a region of not enough slots.
: find-start-slot ( #slots -- slot# ) \ slot# is start of region
>r 0 begin ( test-slot ) ( R: #slots )
while ( bad-slot# ) ( R: #slots )
\ find the first non-zero. count number of succeeding zeros. are there enough?
\ if so, done. if not, go to the next non-zero and start over.
\ XXX there better be enough room left or the whole thing will crash.
\ XXX assume it never fails:
: get-chunk ( #bytes -- virt ) \ acquire dma memory
find-start-slot ( #bytes #slots slot# )
slot>virt ( #bytes virt )
: give-chunk ( virt #bytes -- ) \ return dma memory
virt>slot slot>tbl-addr swap
mem-table #mem-entries /entry * erase
projects / OpenSPARC-T2-SAM / blob