MAJOR = 6 / major # from bdevsw[] / RK05 bootstrap. / / 1995/05/31 - The unit number needs to go in bits 3-5 of bootdev / because the partition number now goes into bits 0-2. / / disk boot program to load and transfer / to a unix entry. / for use with 1 KB byte blocks, CLSIZE is 2. / NDIRIN is the number of direct inode addresses (currently 4) / assembled size must be <= 512; if > 494, the 16-byte a.out header / must be removed / options: none. all options of reading an alternate name or echoing to / the keyboard had to be removed to make room for the / code which understands the new directory structure on disc / constants: CLSIZE = 2. / physical disk blocks per logical block CLSHFT = 1. / shift to multiply by CLSIZE BSIZE = 512.*CLSIZE / logical block size INOSIZ = 64. / size of inode in bytes NDIRIN = 4. / number of direct inode addresses ADDROFF = 12. / offset of first address in inode INOPB = BSIZE\/INOSIZ / inodes per logical block INOFF = 31. / inode offset = (INOPB * (SUPERB+1)) - 1 PBSHFT = -4 / shift to divide by inodes per block WC = -256.*CLSIZE / word count / The boot options and device are placed in the last SZFLAGS bytes / at the end of core by the kernel for autobooting. ENDCORE= 160000 / end of core, mem. management off SZFLAGS= 6 / size of boot flags BOOTOPTS= 2 / location of options, bytes below ENDCORE BOOTDEV= 4 CHECKWORD= 6 .. = ENDCORE-512.-SZFLAGS / save room for boot flags / entry is made by jsr pc,*$0 / so return can be rts pc / establish sp, copy / program up to end of core. nop / These two lines must be present or DEC br start / boot ROMs will refuse to run boot block! start: mov r0,unit mov r1,csr mov $..,sp mov sp,r1 clr r0 1: mov (r0)+,(r1)+ cmp r1,$end blo 1b jmp *$2f / On error, restart from here. restart: clr r0 / clear core to make things clean 2: clr (r0)+ cmp r0,sp blo 2b / initialize rk mov csr,r1 mov $reset+go,rkcs(r1) / reset controller mov $bootnm, r1 mov $2,r0 / ROOTINO jsr pc,iget clr r2 / offset again: jsr pc,readdir beq restart / error - restart mov 4(r0),r4 / dp->d_namlen cmp r4,$bootlen / if (bootlen == dp->d_namlen) bne again / nope, go try next entry mov r0,r3 add $6,r3 / r3 = dp->d_name mov r1,r5 / r5 = filename 9: cmpb (r3)+,(r5)+ bne again / no match - go read next entry sob r4,9b mov (r0),r0 / r0 = dp->d_ino jsr pc,iget / fetch boot's inode br loadfile / 'boot'- go read it / get the inode specified in r0 iget: add $INOFF,r0 mov r0,r5 ash $PBSHFT,r0 bic $!7777,r0 mov r0,dno clr r0 jsr pc,rblk bic $!17,r5 mov $INOSIZ,r0 mul r0,r5 add $buf,r5 mov $inod,r4 1: movb (r5)+,(r4)+ sob r0,1b rts pc readdir: bit $BSIZE-1,r2 bne 1f jsr pc,rmblk / read mapped block (bno) br err / end of file branch clr r2 / start at beginning of buf 1: mov $buf,r0 add r2,r0 / dp = buf+offset add buf+2(r2),r2 / dp += dp->d_reclen tst (r0) / dp->d_ino == 0? beq readdir / yes - go look at next rts pc / return with r0 = &dp->d_ino err: clr r0 / return with rts pc / dp = NULL loadfile: clr bno / start at block 0 of inode in 'inod' / read file into core until / a mapping error, (no disk address) clr r1 1: jsr pc,rmblk br 1f mov $buf,r2 2: mov (r2)+,(r1)+ cmp r2,$buf+BSIZE blo 2b br 1b / relocate core around / assembler header 1: clr r0 cmp (r0),$407 bne 2f 1: mov 20(r0),(r0)+ cmp r0,sp blo 1b / enter program and / restart if return 2: mov ENDCORE-BOOTOPTS, r4 mov unit,r3 ash $3,r3 / unit # in bits 3-5, partition # is 0 bis $MAJOR\<8.,r3 mov ENDCORE-CHECKWORD, r2 mov csr,r1 jsr pc,*$0 br restart / read a mapped block / offset in file is in bno. / skip if success, no skip if fail / the algorithm only handles a single / indirect block. that means that / files longer than NDIRIN+256 blocks (260kb) cannot / be loaded. rmblk: add $2,(sp) mov bno,r0 cmp r0,$NDIRIN blt 1f mov $NDIRIN,r0 1: ash $2,r0 mov addr+2(r0),dno mov addr(r0),r0 bne 1f tst dno beq 2f 1: jsr pc,rblk mov bno,r0 inc bno sub $NDIRIN,r0 blt 1f ash $2,r0 mov buf+2(r0),dno mov buf(r0),r0 bne rblk tst dno bne rblk 2: sub $2,(sp) 1: rts pc read = 4 reset = 0 go = 1 rkcs = 0 / offset from base csr rkwc = 2 rkba = 4 rkda = 6 / rk05 disk driver. / low order address in dno, / high order in r0. rblk: mov r1,-(sp) mov dno,r1 .if CLSIZE-1 ashc $CLSHFT,r0 / multiply by CLSIZE .endif div $12.,r0 ash $4,r0 bis r1,r0 mov unit,r3 ash $13.,r3 bis r3,r0 mov csr,r3 mov r0,rkda(r3) / stuff disc address mov $buf,rkba(r3) / where to put it. mov $WC,rkwc(r3) / yes sir, yes sir, three bags full mov $read+go,(r3) / rkcs - press the button 1: tstb (r3) / rkcs bge 1b mov (sp)+,r1 rts pc bootnm: bootlen = 4 / strlen(bootnm) unit: 0 csr: 0 end: inod = ..-512.-BSIZE / room for inod, buf, stack addr = inod+ADDROFF / first address in inod buf = inod+INOSIZ bno = buf+BSIZE dno = bno+2