; Copyright 1996 Acorn Computers Ltd
;
; Licensed under the Apache License, Version 2.0 (the "License");
; you may not use this file except in compliance with the License.
; You may obtain a copy of the License at
;
; http://www.apache.org/licenses/LICENSE-2.0
;
; Unless required by applicable law or agreed to in writing, software
; distributed under the License is distributed on an "AS IS" BASIS,
; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
; See the License for the specific language governing permissions and
; limitations under the License.
;
TTL => TickEvents
; This file revised by TMD 28-Jan-94 to
; a) Correct internals to time n ticks not n+1
; b) Change externals to add 1 to compensate for user subtracting 1
; c) Fix RemoveTickerEvent to add this node's time onto the next one
; These fix bug MED-02498.
; There are two (centisecond) ticker SWIs :
; SWI CallAfter calls the given address once, after the given number of ticks
; SWI CallEvery " " " " every N centiseconds
; In : R0 is unsigned number of centiseconds
; R1 is address to call
; R2 is value of R12 to pass to code
CallEvery_Code
ADD r10, r0, #1 ; compensate for n+1 bug
B TickTockCommon
CallAfter_Code ROUT
MOV r10, #0
TickTockCommon
Push "r0-r3, lr"
ADD r14, r0, #1024
CMP r14, #1024
BLS %FT99 ; reject 0 and >= &FFFFFC00
[ ChocolateSysHeap
ASSERT ChocolateTKBlocks = ChocolateBlockArrays + 8
LDR r3,=ZeroPage+ChocolateBlockArrays
LDR r3,[r3,#8]
BL ClaimChocolateBlock
MOVVS r3, #TickNodeSize
BLVS ClaimSysHeapNode
|
MOV r3, #TickNodeSize
BL ClaimSysHeapNode
]
BVS %FT97
MOV r3, r2
LDMFD stack, {r0-r2}
STR r1, [r3, #TickNodeAddr]
STR r10, [r3, #TickNodeRedo]
STR r2, [r3, #TickNodeR12]
MOV r1, r3
ADD r0, r0, #1 ; compensate for n+1 bug
BL InsertTickerEvent
Pull "r0-r3, lr"
ExitSWIHandler
99 ADR r0, ErrorBlock_BadTime
[ International
BL TranslateError
]
97
ADD sp, sp, #1*4 ; junk old R0
Pull "r1-r3, lr"
B SLVK_SetV
MakeErrorBlock BadTime
; Data structure :
; chain of nodes
;
; +----------------------------------+
; | Link to next node or 0 |
; +----------------------------------+
; | Reload flag |
; +----------------------------------+
; | Address to call |
; +----------------------------------+
; | Value of R12 |
; +----------------------------------+
; | No of ticks to go before call |
; +----------------------------------+
;
; The head node's no of ticks is decremented until 0
; Subsequent nodes contain the no of ticks to wait when they reach the
; chain head.
; If the reload flag is non-0, the node is reinserted at that number of ticks
; down the chain after every use.
^ 0
TickNodeLink # 4 ;
TickNodeRedo # 4 ; These are together
TickNodeAddr # 4 ;
TickNodeR12 # 4 ; so can LDM them
TickNodeLeft # 4
TickNodeSize # 0
InsertTickerEvent ROUT
; R1 is node pointer, R0 ticks to wait
; R10-R12 corrupted
Push "r0,lr"
PHPSEI r14
LDR r10, =ZeroPage+TickNodeChain
01
MOV r11, r10
LDR r10, [r11, #TickNodeLink]
CMP r10, #0
BEQ %FT02 ; end of chain
LDR r12, [r10, #TickNodeLeft]
CMP r12, r0
SUBLS r0, r0, r12
BLS %BT01 ; node R10 is earlier (or equal) to node R1
SUB r12, r12, r0
STR r12, [r10, #TickNodeLeft]
02
STR r1, [r11, #TickNodeLink]
STR r0, [r1, #TickNodeLeft]
STR r10, [r1, #TickNodeLink]
PLP r14
Pull "r0,pc"
ProcessTickEventChain ROUT
; R0-R3, R10-R12 corruptible
LDR r3, =ZeroPage+TickNodeChain
LDR r1, [r3, #TickNodeLink]
CMP r1, #0
MOVEQ pc, lr ; no timers
LDR r2, [r1, #TickNodeLeft]
SUBS r2, r2, #1
STR r2, [r1, #TickNodeLeft]
MOVHI pc, lr ; nothing to call yet (HI to cope with ordinary 1 -> 0 transition, and 0 -> -1 transition if re-entered while processing two or more events which are due to fire at the same time)
Push "lr" ; save IRQ_lr
MSR CPSR_c, #SVC32_mode+I32_bit ; switch to SVC mode, IRQ's off
Push "lr" ; save SVC_lr
01
LDMIA r1, {r2, r10, r11, r12} ; load next ptr, redo state,
; address and R12val
STR r2, [r3] ; de-link from chain
[ NoARMv5
MOV lr, pc
MOV pc, r11 ; call event handler
|
BLX r11 ; call event handler
]
MOVS r0, r10 ; CallEvery?
BEQ %FT05
BL InsertTickerEvent ; yes, then re-insert timer
B %FT10
05
; Return spent ticker node to heap
MSR CPSR_c, #SVC32_mode ; IRQ's ON for the S L O W bit
MOV r2, r1 ; R2->node to free
[ ChocolateSysHeap
ASSERT ChocolateTKBlocks = ChocolateBlockArrays + 8
LDR r1,=ZeroPage+ChocolateBlockArrays
LDR r1,[r1,#8]
BL FreeChocolateBlock
LDRVS r1, =SysHeapStart
MOVVS r0, #HeapReason_Free
SWIVS XOS_Heap
|
LDR r1, =SysHeapStart
MOV r0, #HeapReason_Free
SWI XOS_Heap
]
; Check for more events at the same level in the list
10
MSR CPSR_c, #SVC32_mode+I32_bit ; IRQ's off again (after returning node to heap, or after naughty CallEvery exits with IRQs on)
LDR r1, [r3, #TickNodeLink] ; get top of list
CMP r1, #0 ; list empty?
BEQ %FT02 ; yes then exit
LDR r0, [r1, #TickNodeLeft]
CMP r0, #0 ; zero time delta?
BEQ %BT01 ; yes then jump
02
Pull "lr" ; restore SVC_lr
MSR CPSR_c, #IRQ32_mode+I32_bit ; back to IRQ mode
Pull "pc" ; pull IRQ_lr from IRQ stack
RemoveTickerEvent_Code
; R0 is address of code to remove, R1 the R12 value
MSR CPSR_c, #SVC32_mode+I32_bit
LDR r10, =ZeroPage+TickNodeChain
01
LDR r11, [r10]
CMP r11, #0
ExitSWIHandler EQ
LDR r12, [r11, #TickNodeAddr]
CMP r12, r0
LDREQ r12, [r11, #TickNodeR12]
CMPEQ r12, r1
MOVNE r10, r11
BNE %BT01
Push "r0-r2, lr"
MOV r2, r11
LDR r11, [r11, #TickNodeLink] ; prev->link = this->link
STR r11, [r10]
TEQ r11, #0 ; if next node exists
LDRNE r14, [r11, #TickNodeLeft] ; then add our time-to-go onto its
LDRNE r0, [r2, #TickNodeLeft]
ADDNE r14, r14, r0
STRNE r14, [r11, #TickNodeLeft]
[ ChocolateSysHeap
ASSERT ChocolateTKBlocks = ChocolateBlockArrays + 8
LDR r1,=ZeroPage+ChocolateBlockArrays
LDR r1,[r1,#8]
BL FreeChocolateBlock
BLVS FreeSysHeapNode
|
BL FreeSysHeapNode
]
Pull "r0-r2, lr"
B %BT01
ReadMetroGnome
LDR r0, =ZeroPage
LDR r0, [r0, #MetroGnome]
ExitSWIHandler
LTORG
END