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sys: kernel comments

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This commit is contained in:
Phil Budne
2016-03-11 16:01:01 -05:00
parent df1d8e29dd
commit 802ab257b9
8 changed files with 260 additions and 233 deletions
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src/sys/s7.s
+115 -107
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@@ -38,18 +38,18 @@ pibreak: " priority interrupt break processing "chain"
"** written: ttydelay -> ttyd1
"** written: ttyrestart -> ttyres1
" referenced in iread:
cnop:
nop
cnop: " fetched as constant in iread
nop
-1
dac 7 " set location 7 to -1
dac 7 " set location 7 to -1 (nothing ever clears it)
clon " enable clock interrupts, reset flag
lac ttydelay
spa
isz ttydelay
skp
jms ttyrestart
lac .dspb "** START CROSSED OUT: written: lac tty
lac ttydelay " tty delay positive?
spa " yes: skip to skp
isz ttydelay " no: done delaying?
skp " not done
jms ttyrestart " yes: start output
"** START CROSSED OUT: written: lac tty
lac .dspb
sna
jmp piret
isz .dsptm
@@ -61,23 +61,24 @@ cnop:
jmp piret
jmp dsprestart "** END CROSSED OUT
1: dssf
jmp 1f
1: dssf " disk flag set?
jmp 1f " no
-1
-1 " set .dskb = -1
dac .dskb
"** 01-s1.pdf page 42
dsrs
dsrs " get disk status in .dske
dac .dske
dscs
dscs " clear status register
jmp piret
1: lds "** BEGIN CROSSED OUT
sma ral
jmp 1f
cdf
"** BEGIN CROSSED OUT
1: lds " load display status (see 03-scope.pdf pg 25)
sma ral " edges flag??
jmp 1f " not set
cdf " clear display flags?
lac .dspb
sna
jmp piret
@@ -88,89 +89,89 @@ cnop:
jmp piret
dsprestart:
lac d1
dac .dspb
lac dspbufp
beg
dac .dspb " set .dsbp = 1
lac dspbufp " load display buf pointer
beg " start display processor
-10
dac .dsptm
dac .dsptm " set .dsptm = -10 (10 ticks)
jmp piret
1: sna ral
jmp .+3
dpcf
jmp piret
sma
jmp 1f
lda
dac .lpba
rlpd
1: sna ral " dataphone flag set (bit 7)??
jmp .+3 " no
dpcf " clear dataphone flag
jmp piret " return
sma " light pen flags (bit 2)
jmp 1f " no
lda " G-2: load display address
dac .lpba " save
rlpd " G-2: resume after light pen stop
jmp piret
1: ksf " (TTY) keyboard flag set?
jmp 1f " no
1: ksf " (TTY) keyboard flag set?
jmp 1f " no
lac ttydelay
sma
lac ttydelay " get TTY delay
sma "
isz ttydelay
krb " read keyboard buffer
dac char " save in char
sad o375 " interrupt char (TTY ALT MODE?)
jmp intrp1 " yes
krb " read keyboard buffer
dac char " save in char
sad o375 " interrupt char (TTY ALT MODE?)
jmp intrp1 " yes
lac d1
jms putchar
dzm char
lac sfiles+0
jms wakeup
dac sfiles+0
lac char
sad o212
skp
jmp piret
lac sfiles+1
sma
xor o400000
dac sfiles+1
lac sfiles+0 " get sleep word for ttyin
jms wakeup " wake processes
dac sfiles+0 " clear sleep word
lac char " get character
sad o212 " odd condition (break???)
skp " yes
jmp piret " no: done
lac sfiles+1 " get ttyout wait word
sma " bit for process 1 already set?
xor o400000 " no, make it so
dac sfiles+1 " save back
"** 01-s1.pdf page 43
jms putcr
jms ttyrestart
jms putcr " output CR next
jms ttyrestart " start output
jmp piret
1: tsf
jmp 1f
1: tsf " TTY output flag set?
jmp 1f " no
tcf
jms ttyrestart
tcf " yes: clear flag
jms ttyrestart " transmit next character
jmp piret
ttyrestart: 0
lac ttydelay
spa
jmp ttyrestart i
lac nttychar
dzm nttychar
sza
jmp 3f
isz ttydelay
lac ttydelay " get tty delay
spa " positive?
jmp ttyrestart i " no: keep waiting
lac nttychar " get pending CR, if any
dzm nttychar " clear it
sza " need to send CR?
jmp 3f " yes
isz ttydelay " increment ttydelay (make more positive)
lac d2
jms getchar
jmp 2f
jms getchar " get a character
jmp 2f " none found??
3:
tls
sad o12
jms putcr
sad o15
skp
jmp ttyrestart i
lac ttydelay
tad o20
rcr
cma
dac ttydelay
tls " start output
sad o12 " newline?
jms putcr " yes: put CR next
sad o15 " CR?
skp " yes
jmp ttyrestart i " no: return
lac ttydelay " get current tty delay
tad o20 " bump by 16
rcr " divide by two
cma " complement
dac ttydelay " save
jmp ttyrestart i
2:
lac sfiles+1
lac sfiles+1 " run out of characters to send: wake user(s)
jms wakeup
dac sfiles+1
jmp ttyrestart i "** written arrow up 2 copies
@@ -270,7 +271,7 @@ ttyrestart: 0
lac sfiles+6
jms wakeup
dac sfiles+6
cla
cla " clear button lights
wbl
jmp piret "** END CROSSED OUT
@@ -292,35 +293,42 @@ piret: " return from priority interrupt
ion " reenable interrupts
jmp 0 i " return from interrupt
" wake sleeping processes
" NOTE!! Called from interrupt service, so avoids indirect!!!
" call:
" AC/ sfiles word (bit vector of processes to wake)
" jms wakeup
" AC/ 0 (to store in sfiles word)
wakeup: 0
dac 9f+t
dac 9f+t " save vector in t0
-mnproc
dac 9f+t+1
lac tadu
dac 9f+t+1 " loop count in t1
lac tadu " get "tad ulist"
dac 2f
lac dacu
lac dacu " get "dac ulist"
dac 2f+1
1:
lac 9f+t
ral
ral " rotate vector up one
dac 9f+t
sma
jmp 2f+2
lac o700000
2: tad ..
sma " high bit set?
jmp 2f+2 " no: skip the fun
lac o700000 " yes: decrement process status (wake)
2: tad .. " (avoiding indirect)
dac ..
lac 2b
lac 2b " advance tad operand by 4 words
tad d4
dac 2b
lac 2b+1
lac 2b+1 " advance tad operand by 4 words
tad d4
dac 2b+1
isz 9f+t+1
jmp 1b
cla
isz 9f+t+1 " done?
jmp 1b " no, keep going
cla " return zero in AC
jmp wakeup i
t = t+2
" call to output CR after LF (NL)
putcr: 0
lac o15
dac nttychar
@@ -347,26 +355,26 @@ intrp1: " here with TTY interrupt character
lac sfiles+1
jms wakeup
dac sfiles+1
jms chkint
jmp piret
jmp 1f
intrp2:
jms chkint " check if user interrupted
jmp piret " no, return from PI
jmp 1f " yes: return from system call
intrp2: " here with display interrupt character
lac d7
dac .int2
lac d3
lac d3 " drain keyboard buffer?
jms getchar
skp
jmp .-3
lac sfiles+2
lac sfiles+2 " wake up any "keyboard" sleepers
jms wakeup
dac sfiles+2
lac sfiles+6
lac sfiles+6 " wake up any "display" sleepers
jms wakeup
dac sfiles+6
jms chkint
jmp piret
jms chkint " check if user interrupted
jmp piret " no, return from PI
1:
lac 0
dac 020
lac .ac
jmp 021
lac 0 " get interrupt PC
dac 020 " save as system call return PC
lac .ac " restore AC from interrupt
jmp 021 " join system call processing!!!