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Merge branch 'master' of https://github.com/DoctorWkt/pdp7-unix

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This commit is contained in:
Warren Toomey
2016-03-03 09:52:40 +10:00
parent a351a527e6 09e7c95c5d
commit 782f677a34
2 changed files with 80 additions and 70 deletions
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40
src/sys/s4.s
View File

@@ -63,27 +63,33 @@ laci: 0
"** 01-s1.pdf page 22
" skip if AC between two values (inclusive)
" jms betwen; low_ptr; high_ptr
" <not between>
" <between>
" listing has an alternate written in
" (which would require 'lac ptr' instead of 'ptr' args?)
betwen: 0
lmq cmq
lac betwen i
lmq cmq " get ~AC in MQ
lac betwen i " get low_ptr
dac 9f+t
isz betwen
lacq
tad 9f+t i
sma
jmp 1f
lac betwen i
isz betwen " skip low_ptr
lacq " get ~AC (-AC-1) from MQ
tad 9f+t i " get low-AC-1
sma " negative (AC >= low)?
jmp 1f " no, return w/o skip
lac betwen i " fetch high_ptr
dac 9f+t
isz betwen
lacq
tad 9f+t i
cma
spa sna
isz betwen " skip high_ptr
lacq " get -AC-1
tad 9f+t i " add to high value (high-AC-1)
cma " complement (AC-high)
spa sna " AC-high <= 0?
1:
isz betwen
lacq
cma
jmp betwen i
isz betwen " no: give happy return
lacq " restore ~AC
cma " restore AC
jmp betwen i " return w/o skip
copy: 0
-1

110
src/sys/s6.s
View File

@@ -185,69 +185,73 @@ dput: 0
t = t+3
" allocate a block for a file, returns disk block number
" AC/ file offset
" jms pget
" AC/ disk block number
pget: 0
lrss 6
dac 9f+t
lrss 6 " convert offset to block
dac 9f+t " save as t0
lac i.flags
"** 01-s1.pdf page 37
and o200000
sza
jmp 2f
lac 9f+t
jms betwen; d0; d6
jmp 1f
tad idskpp
dac 9f+t
lac 9f+t i
sna
jms alloc
dac 9f+t i
jmp pget i
1:
jms alloc
dac 9f+t+1
jms copy; i.dskps; dskbuf; 7
jms copyz; dskbuf+7; 64-7
sza " large file bit set?
jmp 2f " yes
lac 9f+t " no: small file
jms betwen; d0; d6 " block 0..6?
jmp 1f " no
tad idskpp " make into block number pointer
dac 9f+t " save in t0
lac 9f+t i " get disk block number
sna " allocated?
jms alloc " no: allocate now
dac 9f+t i " save (new) disk block number
jmp pget i " return disk block number
1: " here when file block>=7, not "large"
jms alloc " allocate indirect block
dac 9f+t+1 " save as t1
jms copy; i.dskps; dskbuf; 7 " copy all the disk block numbers
jms copyz; dskbuf+7; 64-7 " zero rest of indirect block
lac 9f+t+1 " get indirect block number back
jms dskwr " write indirect block to disk
lac 9f+t+1
jms dskwr
lac 9f+t+1
dac i.dskps
jms copyz; i.dskps+1; 6
dac i.dskps " save indirect as new first block
jms copyz; i.dskps+1; 6 " zero rest of block pointers
lac i.flags
xor o200000
xor o200000 " set "large file"
dac i.flags
2:
lac 9f+t
lrss 6
jms betwen; d0; d6
jms halt " file too big
tad idskpp
dac 9f+t+1
lac 9f+t+1 i
sna
jms alloc
dac 9f+t+1 i
dac 9f+t+2
jms dskrd
lac 9f+t
and o77
tad dskbufp
dac 9f+t+1
lac 9f+t+1 i
sza
jmp pget i
jms alloc
dac 9f+t
2: " here with "large file"
lac 9f+t " get file block number
lrss 6 " divide by 64 (indirects/block)
jms betwen; d0; d6 " ok now?
jms halt " file too big " no, you lose!
tad idskpp " yes: get indirect block pointer
dac 9f+t+1 " save in t1
lac 9f+t+1 i " get indirect block number
sna " allocated?
jms alloc " no, get it now
dac 9f+t+1 i " save (new) indirect block
dac 9f+t+2 " save as t2
jms dskrd " read indirect block
lac 9f+t " get original block number
and o77 " mod by 64
tad dskbufp " get pointer to disk block number
dac 9f+t+1 " save as t1
lac 9f+t+1 i " fetch disk block number
sza " allocated?
jmp pget i " yes: return
jms alloc " no: allocate data block
dac 9f+t " save as t0
lac 9f+t+2 " get indirect block number
jms dskrd " read it in
lac 9f+t " get data block number
dac 9f+t+1 i " save data block number
lac 9f+t+2
jms dskrd
lac 9f+t
dac 9f+t+1 i
lac 9f+t+2
jms dskwr
lac 9f+t
jmp pget i
jms dskwr " write indirect block back
lac 9f+t " get data block back
jmp pget i " return it
t = t+3
iwrite: 0