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Annotation of xinu/sys/kprintf.c, revision 1.1.1.2

1.1.1.2 ! root        1: /* kprintf.c - kprintf, kputc--slightly edited from original Xinu */
1.1       root        2: 
                      3: #include <conf.h>
                      4: #include <kernel.h>
                      5: #include <io.h>
                      6: #include <tty.h>
1.1.1.2 ! root        7: 
        !             8: /* set up macros for appropriate SLU as spec. by SLUCHIP:
        !             9:    if SLUCHIP==6850, #include slu6850.h, #define TTYWRITE ttywrite6850, etc.
        !            10:    if SLUCHIP==7201, #include slu7201.h, #define TTYWRITE ttywrite7201, etc.
        !            11:    if SLUCHIP undef.,#include slu.h, #define TTYWRITE ttywrite  (orig. case)
        !            12:    similarly sluaccess.h, other TTY fns */
        !            13: #include <sluinclude.h>
        !            14: #ifdef ATT7300
        !            15: int    slowtime = 500;
        !            16: /* Xinu console is the serial port on the back, assumed already
        !            17:    initialized by the downloading support */
        !            18: #else
        !            19: int     slowtime = 200;
        !            20: /* MECB console is the console MC6850, init'd by TUTOR */
        !            21: #endif
1.1       root       22: 
                     23: /*------------------------------------------------------------------------
                     24:  *  kprintf  --  kernel printf: formatted, unbuffered output to CONSOLE
                     25:  *------------------------------------------------------------------------
                     26:  */
1.1.1.2 ! root       27: 
        !            28: /* kprintf is the routine to use for polling output, even in the case that */
        !            29: /* the calling program also uses SLU interrupts.  It shuts out interrupts */
        !            30: /* by going high-CPU-priority, saving the old CPU priority locally and */
        !            31: /* reestablishing it on return.  It varies from the original Vol I. Xinu */
        !            32: /* sources by not changing the device control register, but rather just */
        !            33: /* relying on high CPU priority to hold the console (did the original SLU */
        !            34: /* fail to post a transmit ready bit with interrupts enabled??) */
        !            35: 
1.1       root       36: kprintf(fmt, args)             /* Derived by Bob Brown, Purdue U.      */
1.1.1.2 ! root       37:         char *fmt;
1.1       root       38: {
1.1.1.2 ! root       39:   static unsigned short savesr;
        !            40:   int     kputc();
        !            41: 
        !            42:   _disable(&savesr);           /* orig. Xinu had "savestate()" */
        !            43:   _doprnt(fmt, &args, kputc, CONSOLE);
        !            44:   _restore(&savesr);           /* orig. Xinu had "rststate()" */
        !            45:   return(OK);
1.1       root       46: }
                     47: 
                     48: /*------------------------------------------------------------------------
1.1.1.2 ! root       49:  *  kputc  --  write a character on the console (or other SLU)
        !            50:  *  using polled I/O
1.1       root       51:  *------------------------------------------------------------------------
                     52:  */
1.1.1.2 ! root       53: kputc(device,c)
        !            54: int device;
        !            55: register char c;       /* character to print from _doprnt      */
1.1       root       56: {
1.1.1.2 ! root       57:         struct csr *csrptr;
        !            58: /*T*/  int     slowdown;       /* added to delay output because host   */
        !            59: /*T*/                          /* can't take it at 9600 baud           */
        !            60:        if ( c == 0 )
1.1       root       61:                return;
                     62:        if ( c == NEWLINE )
1.1.1.2 ! root       63:                kputc(device, RETURN );
        !            64:        csrptr = (struct csr *)devtab[device].dvcsr;
        !            65:        while ( (csrptr->cstat & SLUTRANSREADY) == 0 ) ;  /* poll for idle*/
        !            66:        csrptr->cbuf = c;
        !            67: /*T*/  for(slowdown=0;slowdown<slowtime;slowdown++) ;
        !            68:        while ( (csrptr->cstat & SLUTRANSREADY) == 0 ) ;  /* poll for idle*/
1.1       root       69: }

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