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more system comments

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phil
2019-10-30 00:53:48 -04:00
parent f9dbe7e946
commit 2b2e057f7f
4 changed files with 54 additions and 43 deletions
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src/sys/s5.s
+22 -18
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@@ -88,40 +88,44 @@ fput: 0
jmp fput i
t = t+1
" helper for special device write routines
" return to caller with next character to write:
" when done return character count to user.
" helper for special device write routines to fetch
" returns next character from user buffer
" when done returns from system call w/ character count in AC.
forall: 0
lac u.base
sad u.limit
jmp 1f " done
lac u.base " get base pointer (again?)
lac u.base " get base pointer (again?? already in AC?!)
ral " rotate MSB into LINK
lac u.base i " fetch word via base pointer
snl " link set?
lrs 9 " no: get low 9 bits
snl " LINK set?
lrs 9 " no: shift high character down
and o777 " mask to 9 bits
jmp forall i " return char
fallr: " jump here for subsequent characters
fallr: " original caller jumps to here for subsequent characters
lac u.base " get base
add o400000 " advance pointer
dac u.base " start from top
jmp forall+1
add o400000 " advance character pointer
dac u.base
jmp forall+1 " start from top
1:
lac u.count
dac u.ac
jmp sysexit
" wait for a condition variable
" prepare to sleep on a (character) device
" word after call is pointer to per-device sleepers word
" (bit vector indexed by ulist entry number)
" bit zero (MSB) of sleepers word is special (device busy?)
" call:
" jmr sleep; sfiles+N
" jms sleep; sfiles+N
" jms swap
sleep: 0
law ulist-1 " pointer to process table
dac 8 " in index register
lac o200000
lmq " get 200000 in MQ
1:
lac u.ulistp i " get current process status word
lmq " get bit for process slot zero in MQ
1: " loop to get mask bit for our process in MQ
lac u.ulistp i " get our process status word (contains swap addr)
sad 8 i " compare to next process table entry
jmp 1f " match
isz 8 " no match: skip other 3 words of process table
@@ -130,13 +134,13 @@ sleep: 0
cla; lrs 1 " shift MQ down one
jmp 1b " loop
1:
tad o100000 " mark process not ready
tad o100000 " increment our status to mark process not ready
dac u.ulistp i
lac sleep i " get sleep variable pointer
dac 9f+t
lac 9f+t i " get sleep variable contents
omq " or in MQ (bit vector of processes waiting)
dac 9f+t i " save
omq " or in MQ (set bit for our process)
dac 9f+t i " write sleep variable
isz sleep " skip sleep variable pointer
jmp sleep i
t = t+1