; 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.
;
; > $.Source.PMF.realtime
; *****************************************************************************
;
; CheckYear - Check for year wrap (year in RTC <> year "YearCMOS")
; and for leap year fudging
;
CheckYear ROUT
Push "R0,R1,R2,R14"
LDR R0, =ZeroPage
LDR R0, [R0, #RTCFitted]
[ HAL
CMP R0, #2048
[ RTCSupport
BLO %FT8
|
BLO %FT15
]
; Ask the RTC what it thinks the year is
Push "R3,R10,R12"
MOV R10, R0
SUB R13, R13, #RTCTimeStruct_BCD_Size
MOV R1, R13
ADRL R2, HALRTC_IICOp
MOV LR, PC
LDR PC, [R0, #HALDevice_RTCReadTime]
; Did we succeed?
CMP R0, #RTCRetCode_OK
LDRB R0, [R13, #RTCTimeStruct_BCD_YearLO]
LDRB R1, [R13, #RTCTimeStruct_BCD_YearHI]
ADD R13, R13, #RTCTimeStruct_BCD_Size
LDRB R2, [R10, #HALDevice_RTCFormatFlags]
Pull "R3,R10,R12"
BNE %FT15
ASSERT RTCFormatFlags_BCD_NeedsYearHelp = 1 :SHL: 2
ASSERT RTCFormatFlags_BCD_YearLOIsGood = 1 :SHL: 3
AND LR, R2, #RTCFormatFlags_BCD_NeedsYearHelp + RTCFormatFlags_BCD_YearLOIsGood
MOVS LR, LR, ROR #3 ; CC = good, CS+EQ = 2 bit, CS+NE = BCD
ADDCS R1, LR, #RTCAddressPHI+1 ; 2 bit=RTCAddressPHI+1, BCD!=RTCAddressPHI+1
BCS %FT9
; Year is reliable; convert R0 & R1 to ints and update CMOS if necessary.
BL BCDToHex
MOV R2, R1
MOV R1, R0 ; YearLO
MOV R0, #YearCMOS
BL Read
CMP R0, R1
MOVNE R0, #YearCMOS
BLNE Write
MOV R0, R2
BL BCDToHex
MOV R1, R0 ; YearHI
MOV R0, #YearCMOS+1
BL Read
CMP R0, R1
MOVNE R0, #YearCMOS+1
BLNE Write
B %FT15
8
] ; HAL
[ RTCSupport :LOR: :LNOT: HAL
TEQ R0, #RTCAddressPHI
MOVEQ R1, #5
MOVNE R1, #6 ; year address (dependant on RTC)
STRB R1, [R13, #-4]!
MOV R1, R13
ORR R0, R0, #1:SHL:29
MOV R2, #1
BL IIC_Op
ORR R0, R0, #1
BL IIC_Op
AND R1, R0, #&FF
LDRB R0, [R13], #4
TEQ R1, #RTCAddressPHI+1
] ; RTCSupport :LOR: :LNOT: HAL
9
MOVEQ R0, R0, LSR #6 ; R0= year MOD 4.
BLNE BCDToHex
MOV R2, R0 ; remember RTC value
MOV R0, #YearCMOS
BL Read
TEQ R1, #RTCAddressPHI+1
ANDEQ R1, R0, #3
MOVNE R1, R0
MOVEQ R14,#4
MOVNE R14,#100
SUBS R2, R2, R1 ; same year ?
Pull "R0,R1,R2,PC", EQ ; [yes, so no bother]
ADDCC R2, R2, R14 ; if lower, then must be carry
ADD R2, R0, R2 ; new year value
CMP R2, #100
BCC %FT10 ; no carry thru to next century
SUB R2, R2, #100
MOV R0, #YearCMOS +1
BL Read
ADD R1, R0, #1
TEQ R1, #100
MOVEQ R1, #0 ; wrap century
MOV R0, #YearCMOS +1
BL Write
10
MOV R1, R2
MOV R0, #YearCMOS
BL Write
15
BL RTCToRealTime
Pull "R0,R1,R2,PC"
; *****************************************************************************
;
; RTCToRealTime - Set RealTime from actual RTC
;
; in: R12 -> BYTEWS
; out: all registers preserved
;
[ {FALSE}
Construct5Byte ROUT
Push R14
B Construct5ByteEntry
]
RTCToRealTime ROUT
Push "R0-R9, R14"
BL ReadTime ; R0 := hours, R1 := minutes
; R2 := days, R3 := months
; R5 := year(lo), R6 := year(hi)
; R7 := seconds, R8 := centiseconds
; R0 will be negative on error. Just skip the update.
CMP R0,#0
Pull "R0-R9, PC",LT
BL ConvertTo5Byte
BL Store5ByteInRealTime
Pull "R0-R9, PC"
RegToRealTime ROUT
Push "R0-R9, R14"
BL ConvertTo5Byte
BL Store5ByteInRealTime
Pull "R0-R9, PC"
ConvertTo5Byte ROUT
Push R14
MOV R4, R5 ; R4 := year MOD 100
MOV R5, R6 ; R5 := year DIV 100
MOV R6, R7 ; R6 := seconds
MOV R7, R8 ; R7 := centiseconds
Construct5ByteEntry
MOV R9, #24
SUB R2, R2, #1 ; decrement day (day=1 => nowt to add)
MLA R0, R9, R2, R0 ; R0 = hours + day*24
MOV R9, #60
MLA R1, R0, R9, R1 ; R1 = mins + hours*60
MLA R6, R1, R9, R6 ; R6 = secs + mins*60
MOV R9, #100
MLA R7, R6, R9, R7 ; R7 = centisecs + secs*100
ADR R0, STMonths-4 ; Point to table (month = 1..12)
LDR R1, [R0, R3, LSL #2] ; get word of offset
ADD R7, R7, R1 ; add to total
; if not had leap day in this year yet, then exclude this year from the
; leap day calculations
CMP R3, #3 ; if month >= 3
SBCS R0, R4, #0 ; then R0,R1 = R4,R5
MOVCC R0, #99 ; else R0,R1 = R4,R5 -1
SBC R1, R5, #0
; want (yl+100*yh) DIV 4 - (yl+100*yh) DIV 100 + (yl+100*yh) DIV 400
; = (yl DIV 4)+ (25*yh) - yh + (yh DIV 4)
; = (yl >> 2) + 24*yh + (yh >> 2)
MOV R0, R0, LSR #2 ; yl >> 2
ADD R0, R0, R1, LSR #2 ; + yh >> 2
ADD R0, R0, R1, LSL #4 ; + yh * 16
ADD R0, R0, R1, LSL #3 ; + yh * 8
; now subtract off the number of leap days in first 1900 years = 460
SUBS R0, R0, #460
BCC BadYear ; before 1900, so bad
CMP R0, #86 ; if more than 86 days, then it's
BCS BadYear ; after 2248, so bad
LDR R9, =ticksperday ; multiply by ticksperday and add to
MLA R7, R9, R0, R7 ; total (no overflow possible as this
; can never be more than 85+31 days)
; now add on (year-1900)*ticksperyear
SUBS R5, R5, #19 ; subtract off 1900
BCC BadYear
MOV R9, #100
MLA R4, R9, R5, R4 ; R4 = year-1900
LDR R0, =ticksperyear ; lo word of amount to add on
MOV R1, #0 ; hi word of amount to add on
MOV R8, #0 ; hi word of result
10
MOVS R4, R4, LSR #1
BCC %FT15
ADDS R7, R7, R0 ; if bit set then add on amount
ADCS R8, R8, R1
BCS BadYear ; overflow => bad time value
15
ADDS R0, R0, R0 ; shift up amount
ADCS R1, R1, R1
TEQ R4, #0 ; if still bits to add in
BNE %BT10 ; then loop
CMP R8, #&100 ; R8 must only be a byte
Pull PC, CC
BadYear
MOV R7, #-1
MOV R8, #-1
Pull PC
Store5ByteInRealTime
Push R14
PHPSEI ; disable IRQs for this bit
STR R7, RealTime +0
STRB R8, RealTime +4
[ :LNOT: AssemblingArthur :LAND: :LNOT: Module
; for now, also put into normal time
LDRB R0, TimerState
TEQ R0, #5
ADREQ R3, TimerAlpha +0
ADRNE R3, TimerBeta +0
STR R7, [R3]
STRB R8, [R3, #4]
]
PLP
Pull PC
; *****************************************************************************
tickspersecond * 100
ticksperminute * tickspersecond * 60
ticksperhour * ticksperminute * 60
ticksperday * ticksperhour * 24
ticksperyear * ticksperday * 365 ; &BBF81E00
STMonths
& &00000000 ; Jan
& &0FF6EA00 ; Feb
& &1E625200 ; Mar
& &2E593C00 ; Apr
& &3DCC5000 ; May
& &4DC33A00 ; Jun
& &5D364E00 ; Jul
& &6D2D3800 ; Aug
& &7D242200 ; Sep
& &8C973600 ; Oct
& &9C8E2000 ; Nov
& &AC013400 ; Dec
& &F0000000 ; terminator, must be less than this (+1)
LTORG
END