/* utboot.s 6.2 83/09/29 */
* VAX tape boot block for distribution tapes
* reads a program from a tp directory on a tape and executes it
* program must be stripped of the header and is loaded ``bits as is''
* you can return to this loader via ``ret'' as you are called ``calls $0,ent''
.set HDRSIZ,040 /* size of file header for VAX */
.set MAGIC,0410 /* file type id in header */
.set TSIZ,4 /* text size */
.set DSIZ,8 /* data size */
.set BSIZ,12 /* bss size */
.set TENT,024 /* task header entry loc */
/* tp directory definitions */
.set FILSIZ,38 /* tp direc offset for file size */
.set BNUM,44 /* tp dir offset for start block no. */
.set ENTSIZ,64 /* size of 1 TP dir entry, bytes */
.set PTHSIZ,32 /* size of TP path name, bytes */
.set BLKSIZ,512 /* tape block size, bytes */
.set NUMDIR,24 /* no. of dir blocks on tape */
.set ENTBLK,8 /* no. of dir entries per tape block */
/* processor registers and bits */
.set TXCS_pr,7 /* bit position of TXCS ready bit */
.set RXCS_pd,7 /* bit position of RXCS done bit */
/* UT commands and bits */
.set UT_crdy,7 /* bit pos. */
.set UT_gapsd,13 /* bit; aka "positioning in progress" */
.set UTDENS,0x4c0 /* 1600 bpi, PDP-11 format */
/* local stack variables */
.set tapa,-4 /* desired tape addr */
.set mtapa,-8 /* current tape addr */
.set name,-8-PTHSIZ /* operator-typed file name */
movl $RELOC,fp /* core loc to which to move this program */
addl3 $name,fp,sp /* set stack pointer; leave room for locals */
movc3 $end,(r0),(fp) /* move boot up to relocated position */
bsbw rew /* rewind input tape */
movab name(fp),r4 /* start of filename storage */
movzbl $'=,r0 /* prompt character */
bsbw putc /* output char to main console */
/* read in a file name */
movl r4,r1 /* loc at which to store file name */
bsbw getc /* get input char's in file name */
cmpb r0,$012 /* terminator ? */
subl3 r4,r1,r9 /* size of path name */
beql start /* dumb operator */
/* user-specified TP filename has been stored at name(fp) */
/* read in entire tp directory contents into low core */
movl $8,tapa(fp) /* tp directory starts at block 8 */
movl $(NUMDIR*BLKSIZ),r6 /* no. bytes in total dir */
bsbw taper /* read no. bytes indicated */
/* search entire directory for user-specified file name */
clrl r5 /* dir buff loc = 0 */
cmpc3 r9,(r5),(r4) /* see if dir entry matches filename */
beql fndfil /* found match */
acbl $NUMDIR*BLKSIZ-1,$ENTSIZ,r5,nxtdir
/* see if done with tp dir */
brw start /* entry not in directory; start over */
/* found desired tp dir entry */
movzwl BNUM(r5),tapa(fp) /* start block no., 2 bytes */
addl2 $7,tapa(fp) /* skip 7 boot blocks */
movzwl FILSIZ(r5),r6 /* low 2 bytes file size */
insv FILSIZ-1(r5),$16,$8,r6 /* file size, high byte */
cmpl r6,$RELOC-512 /* check if file fits below stack */
blss filok /* file o.k. */
brw start /* file too large */
/* time to read in desired file from tape */
subl3 r7,$RELOC-4,r0 /* no. bytes to clear */
/* time to jump to start of file & execute */
/* taper: movcTAPE (r6),tapa(fp),0 */
bsbb rew /* beginning of tape */
bsbb rrec /* advance 1 block; never want blk 0 */
cmpl mtapa(fp),tapa(fp) /* current position .vs. desired */
/* rew: rewind the tape */
clrl mtapa(fp) /* current position */
movw $UTDENS,UTTC(%rUT) /* select drive */
movw $UT_REW+GO,UTCS1(%rUT)
/* rrec: read 1 block from mag tape into page (r0) */
/* pushl r0; movzbl $'r,r0; bsbw putc; movl (sp)+,r0; */
movw $-256,UTWC(%rUT) /* !!!!!!!!!!!!!! */
bisl3 $MRV|MR_BDP1,r0,UBA_MAP(%rUBA)
movw $UTDENS,UTTC(%rUT) /* select drive */
movw $UT_RCOM+GO,UTCS1(%rUT)
bisl2 $BNE,UBA_DPR1(%rUBA)
movw $UTDENS,UTTC(%rUT) /* select drive */
movw $UT_SREV+GO,UTCS1(%rUT)
incl r0 /* next page no. */
incl mtapa(fp) /* mag tape block position */
bbc $RXCS_pd,r0,getc /* receiver ready ? */
bbc $TXCS_pr,r2,putc /* transmitter ready ? */
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