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https://github.com/DoctorWkt/unix-jun72.git
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ralph.logan
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54
pages/e05-01
Normal file
54
pages/e05-01
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@ -0,0 +1,54 @@
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/ u5 - unix
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mget:
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mov *u.fofp,mq / file offset ln mq
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clr ac / later to be high sig
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mov $-8,lsh / divide ac/mq by 256.
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mov mq,r2
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blt $10000,i.flgs / lg/sm is this a large or small file
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bne 4f / branch for large file
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blt $!17,r2
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bne 3f / branch if/r2 greater than or equal to 16
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blc $!16,r2 / clear all bits but bits 1,2,3
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mov 1.dskp(r2),r1 / r1 has physical block number
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bne 2f / lf physical block num is zero then need a new block
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/ for file
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jsr rO,alloc / allocate a new block
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mov r1,i.dskp(r2) / physical block number stored in i-node
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jsr r0,setimod / set inode modified byte (imod)
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jsr r0,clear / zero out disk/drum block just allocated
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2:
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rts rO
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3: / adding on block which changes small file to a large file
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jsr rD,alloc / allocate a new block for this file; block number
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/in r1
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jsr r0,wslot / set up I/0 buffer for write, r5 points to first
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/ data word in buffer
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mov $8.,r3 / next 6 instructions transfer old physical block
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/ pointers
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mov $i.dskp,r2 / into new indirect block for the new large file
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1:
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mov (r2),(r5)+
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clr (r2)+
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dec r3
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bgt 1b
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mov $256.-8.,r3 / clear rest of data buffer
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1:
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clr (r5)+
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dec r3
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bgt 1b
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jsr rO,dskwr / write new indirect block on disk
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mov r1,i.dskp / put pointer to indirect block ln i—node
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bis $10000,i.f1gs / set large file blt in i.flgs word of i-node
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jsr rO,setlmod / set i-node modified flag
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br mget
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4: / large file
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mov 9-8,lsh / divide byte number by 256.
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blc $!776,r2 / zero all bits but 1,2,3,4,5,6,7,8; gives offset
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/ in indirect block
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mov r2,-(sp) / save on stack
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mov mq,r2 / calculate offset in i-node for pointer to proper
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/ indirect block
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bic $!16,r2
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mov i.dskp(r2),r1
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bne 2f / if no indirect block exists
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jsr r0,alloc / allocate a new block
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57
pages/e05-02
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57
pages/e05-02
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@ -0,0 +1,57 @@
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mov r1,i.dskp(r2) / put block number of new block in i-node
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jsr r0,setimod / set i—node modified byte
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jsr rO,clear / clear new block
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2:
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jsr r0,dskrd / read in indirect block
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mov (sp)+,r2 / get offset
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mov r1 ,-(sp) / save block number of indirect block on stack
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add r5,r2 / r5 points to first word in indirect block, r2
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/ points to location of inter
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mov (r2),r1 / put physical block no of block in file
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/ sought in r1
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bne 2f / if no block exists
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jsr r0,alloc / allocate a new block
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mov r1,(r2) / put new block number into proper location ln
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/ indirect block
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mov (sp)+,r1 / get block number of indirect block
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mov (r2 ,—(sp) / save block number of new block
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jsr r0,wslot
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jsr r0,dskwr / write newly modified indirect block back out
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/ on disk
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mov (sp),r1 / restore block number of new block
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jsr r0,clear / clear new block
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2:
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tst (sp)+ / bump stack pointer
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rts r0
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alloc:
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mov r2,—(sp) / save r2, r3 on stack
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mov r3,—(sp)
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mov $systm,r2 / start of inode and free storage map for drum
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tst cdev
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beq 1f / drum ls device
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mov $mount,r2 / dl k or tape is device, start of inode and free
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/ storage map
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1:
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mov (r2)+,r1 / first word contains number of bytes in free
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/ storage map
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asl r1 / multiply r1 by eight gives, number of blocks in device
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asl r1
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asl r1
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mov r1 ,-(sp) / save # of blocks in device on stack
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clr r1 / r1 contains bit count of free storage map
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1:
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mov (r2)+,r3 / word of free storage map in r3
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bne 1f / branch if any free blocks in this word
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ndd $16.,r1
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cmp r1 ,(sp) / have we examined all free storage bytes
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blo 1b
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jmp panic / found no tres storage
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1:
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asr r3 / find a free block
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bcs 1f / branch when free block found; bit for block k is in
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/ byte k/8 / 1n bit x (mod s)
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lnc r1 / increment bit count in bit k (mod8)
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br 1b
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1:
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54
pages/e05-03
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54
pages/e05-03
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@ -0,0 +1,54 @@
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tst (sp)+ / bump sp
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jsr r0,3f / have found a free block
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bic r3,(r2) / set bit for this block .e. assign block
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br 2f
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free:
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mov r2,-(sp) / save r2, r3
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mov r3,—(sp)
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jsr r0,3f / set up bit mask and word no. in free storage map
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/ for block
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bis r3,(r2) / set free storage block bit; indicates free block
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2:
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mov (sp)+,r3 / restore r2, r3
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mov (sp)+,r2
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tst cdev / cdev = 0, block structured, drum; cdev = 1
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/ mountable device
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bne 1f
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incb smod / set super block modified for drum
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rts r0
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1:
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incb mmod / set super block modified for mountable device
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rts r0
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3:
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mov r1,r2 / block number, k, = 1
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me $!7,r2 / clear all bits but 0,1,2; r2 = (k) mod (8)
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clr r3
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bisb 2f(r2),r3 / use mask to set bit in r3 corresponding to
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/ (k) mod 8
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mov r1,1r2 / divide block number by 16
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asr r2
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asr r2
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asr r2
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asr r2
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bcc 1f / branch if bit 3 in r1 was 0 i.e., bit for block is in
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/ lower half of word
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swab r3 / swap bytes in r3; bit in upper half of word in free
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/ storage map
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1:
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asl r2 / multiply block number by 2; r2 = k/8
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add $systm+2,r2 / address of word of free storage map for drum
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/ with block bit in it
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tst cdev
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beq 1f / cdev = O indicates device is drum
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add $mount-systm,r2 / address of word of free storage map for
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/ mountable device with bit of block to be
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/ freed
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1:
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rts r0 / return to 'free'
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2:
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.byte 1,2,4,10,20,40,100,200 / masks for bits 0,...,7
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access:
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jsr r0,iget / read in i-node for current directory (i-number
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/ passed in r1)
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mov i.flgs,r2
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53
pages/e05-04
Normal file
53
pages/e05-04
Normal file
@ -0,0 +1,53 @@
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cmpb i.uid,u.uid / is user same as owner of file
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hne 1f / no, then branch
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asrb r2 / shlft owner read write bits into non owner
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/ read/write blts
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asrb r2
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1:
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bit r2,(r0)+ / test read—wr1te flags agalnst argument Ln
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/ access call
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bne 1f
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tstb u.uid
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beq 1f
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jmp error
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1:
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rts r0
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setimod:
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movb $1,imod / set current i—node modified bytes
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mov s.time,i.mtim / put present tlme into file modified time
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mov s.time+2,i.mtim+2
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rts r0
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imap: / get the byte that has the allocation bit for the i—number contained
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/in r1
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mov $1,mq / put 1 in the mq
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mov r1,r2 / r2 now has i—number whose byte in the map we
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/ must find
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sub $41.,r2 / r2 has i-41
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mov r2,r3 / r3 has i-41
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blc $!7,r3 / r3 has (i-41) mod 8 to get the bit position
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mov r3,lsh / move the 1 over (i-41) mod 8 positions to the left
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/ to mask the correct bit
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asr r2
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asr r2
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asr r2 / r2 has (i-41) base 8 of the byte no. from the start of
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/ the map
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mov r2,-(sp) / put (i-41) base 8 on the stack
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mov $systm,r2 / r2 points to the in-core image of the super
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/ block for drum
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tst cdev / is the device the disk
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beg 1f / yes
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add $mount—systm,r2 / for mounted device, r2 points to 1st word
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/ of its super block
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1:
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add (r2)+,(sp) / get byte address of allocation bit
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add (sp)+,r2 / ?
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add $2,r2 / ?
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rts r0
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iget:
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cmp r1, ii / r1 = i-number of current flle
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bne 1f
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cmp idev,cdev / ls device number of i-node = current device
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beq 2f
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1:
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tstb imod / has i-node of current file been modified i.e.,
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/ lmod set
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57
pages/e05-05
Normal file
57
pages/e05-05
Normal file
@ -0,0 +1,57 @@
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beq 1f
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clrb imod / if it has, we must write the new i-node out on disk
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mov r1 ,-(sp)
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mov cdev,-(sp)
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mov ii,r1
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mov idev,cdev
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jsr rO,icalc; 1
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mov (sp)+,cdev
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mov (sp)+,r1
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1:
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tst r1 / is new i-number non zero
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beq 2f / branch if r1=0
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tst cdev / is the current device number non zero (i.e., device
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/ =/ drum)
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une 1f / branch 1f cdev =/ 0
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cmp r1 ,mnti / mnti is the i-number of the cross devlce
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/ file (root directory of mounted devlce)
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bne 1f
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mov mntd,cdev / make mounted device the current device
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mov rootdir,r1
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1:
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mov r1 ,ii
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mov cdev,idev
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jsr r0,1calc; 0 / read 1n i-node ii
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2:
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mov ii,r1
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rts r0
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icalc: / i-node i is located in block (i+31.)/16. and begins 32.*
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/ (i+31)mod16 bytes from its start
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add $31.,r1 / add 31. to i-number
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mov r1,—(sp) / save i+.31. on stack
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asr r1 / divide by 16.
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asr r1
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asr r1
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asr r1 / r1 contains block number of block in which
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/ i-node exists
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jsr r0,dskrd / read in block containlng i-node i.
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tst r0
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beg 1f / branch to wslot when argument in icalc call = 1
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jsr r0,wslot / set up data buffer for write (will be same buffer
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/ as dskrd got)
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1:
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bic $!17,(sp) / zero all but last 4 bits; gives (i+31.) mod 16
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mov (sp)+,mq / calculate offset in data buffer; 32.*(i+31.)mod16
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mov $5,lsh / for i-node i.
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add mq,r5 / r5 points to flrst word ln i-node i.
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mov $inode,r1 / inode is address of first word of current i-node
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mov $16.,r3
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tst (r0)+ / branch to 2f when argument in icalc call = 0
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beq 2f / r0 now contains proper return address for rts r0
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1:
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mov (r1 )+,(r5)+ / over write old i-node
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dec r3
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bgt 1b
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jsr r0,dskwr / write inode out on device
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44
pages/e05-06
Normal file
44
pages/e05-06
Normal file
@ -0,0 +1,44 @@
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rts r0
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2:
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mov (r5)+,(r1)+ / read new i-node into "inode" area of core
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dec r3
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bgt 2b
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rts r0
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itrunc:
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jsr r0,iget
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mov $i.dskp,r2 / address of block pointers in r2
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1:
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mov (r2)+,r1 / move physical block number into r1
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beg 5f
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mov r2,-(sp)
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blt $10000,i.flgs / test large file bit?
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beq 4f / if clear, branch
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mov r1,-(sp) / save block number of indirect block
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jsr r0,dskrd / read in block, 1st data word pointed to by r5
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mov $256.,r3 / move word count into r3
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2:
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mov (r5)+,r1 / put 1st data word in r1; physical block number
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beq 3f / branch if zero
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mov r3,-(sp) / save r3, r5 on stack
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mov r5,-(sp)
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jsr r0,free / free block in free storage map
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mov (sp)+,r5
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mov (sp)+,r3
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3:
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dec r3 / decrement word count
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bgt 2b / branch if positive
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mov (sp)+,r1 / put physical block number of indirect block
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4:
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jsr rO,free / free indirect block
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mov (sp)+,r2
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5:
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cmp r2,$i.dskp+16.
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bne 1b / branch until all i.dskp entries check
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bic $10000,iflgs / clear large file bit
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cl.r i.size / zero file size
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jsr r0,copyz; i.dskp; i.dskp+16. / zero block pointers
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jsr rO,setimod / set i-node modified flag
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mov ii,r1
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rts r0
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