usr/src/sys/vax/mdec/htboot.c

/*      htboot.c        4.1     83/02/16        */

/*
 * VAX tape boot block for distribution tapes
 * works on massbus tu10/te16/tu45/tu77
 *
 * 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    RELOC,0x70000
/* a.out defines */
        .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    RXCS,32
        .set    RXDB,33
        .set    TXCS,34
        .set    TXDB,35
        .set    RXCS_DONE,0x80
        .set    TXCS_RDY,0x80
        .set    TXCS_pr,7       /* bit position of TXCS ready bit */
        .set    RXCS_pd,7       /* bit position of RXCS done bit */
/* MBA registers */
        .set    MBA_CSR,0       /* configuration and status register */
        .set    MBA_CR,4        /* MBA control reg */
        .set    MBA_SR,8        /* MBA status reg */
        .set    MBA_VAR,12      /* MBA virt addr reg */
        .set    MBA_BCR,16      /* MBA byte count reg */
        .set    MBA_MAP,0x800   /* start of MBA map reg's */
        .set    MRV,0x80000000
/* TE16/TU45/TU77 mba registers */
        .set    HTCS1,0         /* HT control 1 reg */
        .set    HTDS,4          /* status reg */
        .set    HTER,8          /* error reg */
        .set    HTAS,16         /* attention summary */
        .set    HTFC,20         /* frame count */
        .set    HTTC,36         /* HT tape control */
/* HT commands */
        .set    GO,1            /* GO bit */
        .set    HT_REW,6        /* rewind, on-line */
        .set    HT_DCLR,010     /* drive clear */
        .set    HT_SREV,032     /* space reverse */
        .set    HT_RCOM,070     /* read forward */
/* HT bits */
        .set    ERR,040000      /* composite error bit in status reg */
        .set    TCHAR,012300    /* unit 0, odd parity, PDP11, 1600 BPI NRZ, */
                                /* abort on error - for tape controller */
        .set    DRDY,0200       /* HT/drive ready in status reg */
        .set    HT_pd,7         /* bit position of HT DRDY bit */
        .set    HT_pe,14        /* bit position of HT ERROR bit */
/* local stack variables */
        .set    tapa,-4         /* desired tape addr */
        .set    mtapa,-8        /* current tape addr */
        .set    name,-8-PTHSIZ  /* operator-typed file name */
/* register usage */
        .set    rMBA,r10
        .set    rHT,r11

/* initialization */
init:
        mull2   $0x80,%rHT
        addl2   $0x400,%rHT
        addl2   %rMBA,%rHT
        movl    $RELOC,fp       /* core loc to which to move this program */
        addl3   $name,fp,sp     /* set stack pointer, leaving room for locals */
        clrl    r0
1:
        movc3   $end,(r0),(fp)  /* move boot up to relocated position */
        jmp     start+RELOC
start:
        movl    $1,MBA_CR(%rMBA)        /* MBA init */
        movl    $TCHAR,HTTC(%rHT)       /* drive no., etc. */
        movl    $HT_DCLR+GO,HTCS1(%rHT) /* drive clear */
        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 */
nxtc:
        bsbw    getc                    /* get input char's in file name */
        cmpb    r0,$012                 /* terminator ? */
        beql    nullc
        movb    r0,(r1)+
        brb     nxtc
nullc:
        subl3   r4,r1,r9                /* size of path name */
        beql    start                   /* dumb operator */
        clrb    (r1)+
        incl    r9
/* user-specified TP filename has been stored at name(fp) */
/* read in entire tp directory contents into low core */
dirred:
        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 */
nxtdir:
        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 */
fndfil:
        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 */
filok:
        movl    r6,r7                   /* save r6 */
        bsbb    taper
        bsbw    rew
/* clear core */
        subl3   r7,$RELOC-4,r0          /* no. bytes to clear */
1:
        clrb    (r7)+
        sobgtr  r0,1b
/* time to jump to start of file & execute */
        addl3   $20,fp,ap
        clrl    r5
        calls   $0,(r5)
        brw     start
/* taper: movcTAPE (r6),tapa(fp),0 */
rew2:
        bsbb    rew                     /* beginning of tape */
taper0:
        bsbb    rrec                    /* advance 1 block; never want blk0 */
taper:
        clrl    r0                      /* page no. */
        cmpl    mtapa(fp),tapa(fp)      /* current position .vs. desired */
        bgtr    rew2
        blss    taper0
1:
        bsbb    rrec
        acbl    $1,$-BLKSIZ,r6,1b
        rsb
/* rew: rewind the tape */
rew:
        clrl    mtapa(fp)               /* current position */
        movl    $HT_REW+GO,HTCS1(%rHT)  /* rewind */
        rsb
/* rrec: read 1 block from mag tape into page (r0) */
rrec:
        /* pushl r0; movzbl $'r,r0; bsbw putc; movl (sp)+,r0; */
        movl    HTDS(%rHT),r2
        bbc     $HT_pd,r2,rrec          /* HT & drive ready ? */
        movl    $-BLKSIZ,MBA_BCR(%rMBA)
        bisl3   $MRV,r0,MBA_MAP(%rMBA)
        clrl    MBA_VAR(%rMBA)
        movl    $HT_RCOM+GO,HTCS1(%rHT) /* read forward */
1:
        movl    HTDS(%rHT),r2
        bbc     $HT_pd,r2,1b
        movl    HTER(%rHT),r2
        bbc     $HT_pe,r2,2f            /* any read errors ? */
        clrl    HTDS(%rHT)              /* clear status - try to recover */
        mnegl   $1,HTFC(%rHT)           /* frame count for backspace */
        movl    $HT_SREV+GO,HTCS1(%rHT) /* space reverse */
        brb     rrec
2:
        incl    r0                      /* next page no. */
        incl    mtapa(fp)               /* mag tape block position */
        rsb
getc:
        mfpr    $RXCS,r0
        bbc     $RXCS_pd,r0,getc        /* receiver ready ? */
        mfpr    $RXDB,r0
        extzv   $0,$7,r0,r0
        cmpb    r0,$015
        bneq    putc
        bsbb    putc
        movb    $0,r0
        bsbb    putc
        movb    $012,r0
putc:
        mfpr    $TXCS,r2
        bbc     $TXCS_pr,r2,putc        /* transmitter ready ? */
        extzv   $0,$7,r0,r0
        mtpr    r0,$TXDB
        rsb
end: