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Bovs_v1.0
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MemMan
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MemMan.asm
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Assembly Source File
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1992-02-19
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8KB
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283 lines
********************************************************************************
*
* MemMan
* Version 3.0
* Low-Memory Manager
* Copyright 1992 Bryan Ford
* See MemMan.doc for distribution requirements
*
********************************************************************************
* $Id$
* Assemble with A68k version >2.71.
include "exec/types.i"
include "exec/lists.i"
include "exec/ables.i"
include "exec/memory.i"
include "exec/libraries.i"
include "exec/semaphores.i"
include "exec/funcdef.i"
include "exec/exec_lib.i"
include "bry/macros.i"
include "bry/memman.i"
_intena equ $dff09a
STRUCTURE MemManSem,SS_SIZE ; SignalSemaphore
UBYTE mms_MemCrunch ; Flag: we're currently having a memory crunch
BYTE mms_pad
ULONG mms_AppCount ; Number of apps using MemMan now
STRUCT mms_MMList,MLH_SIZE ; List we link MMNodes onto
LABEL mms_Code ; Copied MemMan library code
; Structure is continued farther down... (hehe)
code text
xdef MMInit,MMFinish,MMAddNode,MMRemNode
xdef _MMInit,_MMFinish,_MMAddNode,_MMRemNode
* This code is copied into the global MemManSem structure.
* The first six bytes are overwritten with a JMP instruction
* whenever MemMan is not in use.
* Immediately after that is the old AllocMem vector
* (the last part of the JSR instruction).
* Yup, self-modifying code - isn't it beautiful? :-)
* This makes each AllocMem() call slightly faster and should be fine if we
* are very careful of caching (which we are). Since the only self-modifying
* code we use is in MEMF_PUBLIC memory, there should be no virtual or protected
* memory problems either.
codest:
movem.l d0/d1,-(sp) ; Save registers (4 bytes)
jsrinst:
jsr $12345678 ; Call regular AllocMem() (2 + 4 bytes)
tst.l d0
bz.b \failed
\out
addq #8,sp ; Succeeded on the first try
rts
\failed:
cmp.b codest-mms_Code+mms_MemCrunch(pc),d0 ; Avoid recursion from GetRidFuncs
bz.b \out
movem.l a2-a3,-(sp)
DISABLE a0 ; AllocMem only requires FORBID, but the MMList requires DISABLE
lea codest-mms_Code+mms_MemCrunch(pc),a0
st.b (a0)
move.l codest-mms_Code+mms_MMList+LH_HEAD(pc),a2
move.l jsrinst+2(pc),a3
\retry:
move.l LN_SUCC(a2),d1 ; Traverse the list forwards
bz.s \fin ; (kill HIGHEST priority nodes first)
move.l mmn_GetRidFunc(a2),a1 ; Call the GetRidFunc
move.l mmn_GetRidData(a2),a0
move.l d1,a2 ; Find next node BEFORE call
movem.l 8(sp),d0/d1
jsr (a1)
tst.l d0
bz.b \retry
movem.l 8(sp),d0/d1 ; Try allocating again
jsr (a3)
tst.l d0
bz.b \retry
\fin:
move.l a0,-(sp) ; Some nasty apps rely on d1/a0/a1...
lea codest-mms_Code+mms_MemCrunch(pc),a0
clr.b (a0)
ENABLE a0
movem.l (sp)+,a0/a2-a3
addq.l #8,sp ; Pop AllocMem args off stack
rts
semname:
dc.b "MemMan21",0
ds.w 0
codefin:
; Continuation of MemManSem structure (now that we know the code size)
STRUCT mms_Code_def2,(codefin-codest)
LABEL mms_SIZEOF
*** Initialize MemMan - patches AllocMem()
* Returns:
* d0 = Nonzero if successful, zero if failed
MMInit:
_MMInit:
apush
move.l 4,a6
FORBID
lea semname(pc),a1 ; See if the semaphore already exists
jsr _LVOFindSemaphore(a6)
move.l d0,semaphore
bnz \oldsem
\newsem:
move.l #mms_SIZEOF,d0 ; Allocate the public memory block
move.l #MEMF_PUBLIC!MEMF_CLEAR,d1
jsr _LVOAllocMem(a6)
move.l d0,semaphore
bz \outnomem
move.l d0,a5
lea mms_MMList(a5),a0 ; Initialize the data area
NEWLIST a0
move.w #1,mms_AppCount(a5)
lea mms_Code+(semname-codest)(a5),a0
move.l a0,LN_NAME(a5)
lea codest(pc),a0 ; Copy the public code
lea mms_Code(a5),a1
move.l #codefin-codest,d0
jsr _LVOCopyMem(a6)
move.l a6,a1 ; SetFunction AllocMem()
lea mms_Code(a5),a0
move.l a0,d0
movea.w #_LVOAllocMem,a0
jsr _LVOSetFunction(a6)
move.l d0,mms_Code+(jsrinst-codest)+2(a5) ; Set JSR vector
cmpi.w #36,LIB_VERSION(a6) ; Clear the cache after setting vector
blo.b \newsemcc
jsr _LVOCacheClearU(a6)
\newsemcc:
move.l a5,a1 ; Add to system semaphore list
move.l a5,a0 ; BUUUUUUUUUUUUUUUG in 1.3!!!
jsr _LVOAddSemaphore(a6)
bra \outok
\oldsem: ; Semaphore was already in memory
move.l d0,a5
addq.w #1,mms_AppCount(a5)
cmp.w #$4ef9,mms_Code(a5) ; See if we have to reactivate the code
bne.s \codefine
move.l codest(pc),mms_Code(a5) ; Restore the first six bytes
move.w codest+4(pc),mms_Code+4(a5) ; No more or we'll trash the vector
cmpi.w #36,LIB_VERSION(a6) ; Clear the cache after changing code
blo.s \oldsemcc
jsr _LVOCacheClearU(a6)
\oldsemcc:
\codefine:
\outok:
lea mms_MMList(a5),a0
move.l a0,mmlist
PERMIT
moveq #1,d0
\out:
apop
rts
\outnomem
PERMIT
moveq #0,d0
bra.b \out
*** Uninstall our application from the memory manager
MMFinish:
_MMFinish:
apush
move.l 4,a6
move.l semaphore,d0 ; Never successfully initialized?
bz \out
move.l d0,a5
FORBID
subq.w #1,mms_AppCount(a5)
bnz.s \otherapps
move.w #$4ef9,mms_Code(a5) ; Quick bounce with a JMP instruction
move.l mms_Code+(jsrinst-codest)+2(a5),mms_Code+2(a5)
cmpi.w #36,LIB_VERSION(a6) ; Clear the cache after changing code
blo.s \cc
jsr _LVOCacheClearU(a6)
\cc:
\otherapps:
PERMIT
clr.l semaphore ; Safety
\out:
apop
rts
*** Add an MMNode (if it wasn't already on the MMList)
* a1 = Pointer to MMNode
MMAddNode:
_MMAddNode:
DISABLE a0
cmp.b #MMNT_LINKED,LN_TYPE(a1) ; Don't add a node twice
bne.b mmadd
ENABLE a0,NOFETCH
rts
mmadd
move.l a6,-(sp)
move.l a0,a6
move.b #MMNT_LINKED,LN_TYPE(a1) ; Mark it as added
move.l mmlist,a0 ; Add it to the global list in prioritized order
jsr _LVOEnqueue(a6)
ENABLE
move.l (sp)+,a6
rts
*** Remove an MMNode (only if it was on the MMList)
* a1 = Pointer to MMNode
MMRemNode:
_MMRemNode:
DISABLE a0
cmp.b #MMNT_LINKED,LN_TYPE(a1) ; Don't remove unless it was added
beq.b mmremove
ENABLE a0,NOFETCH
rts
mmremove
clr.b LN_TYPE(a1) ; Mark it as not added
REMOVE ; Remove it from the public MMList
ENABLE a0
rts
bss __MERGED
semaphore ds.l 1 ; Pointer to public semaphore
mmlist ds.l 1 ; Points to mms_MMList in MemManSem
end