C/C++ Interactive Guide/c-cplusplus-interactive-guide.iso/c_ref/csource3/115_01/ed8.c

Text File | 1979-12-31 | 5KB | 279 lines

/* Screen editor:  operating system module
 *
 * Source:  ed8.c
 * Version: June 19, 1981.
 */

/* all calls to the operating system are made here.
 * only this module and the assembler libraries will have to be
 * rewritten for a new operating system.
 */

/* the routines syscstat(), syscin() and syscout() come in
 * two flavors:  CP/M version 2.2 and CP/M version 1.4.
 * Comment out which ever you don't use.
 */

/* CP/M 2.2 versions of syscstat(), syscin(), syscout() */

/* return -1 if no character is ready from the console.
 * otherwise, return the character.
 */

syscstat()
{
    return(cpm(6,-1));
}

/* wait for next character from the console.
 * do not echo it.
 */

syscin()
{
int c;
    while ((c=cpm(6,-1))==0) {
        ;
    }
    return(c);
}

/* print character on the console */

syscout(c) char c;
{
    cpm(6,c);
    return(c);
}

/* CP/M 1.4 versions of syscstat(), syscin(), syscout() */

/* start comment out ----------
#asm
;
;    bios(n,bc)
;
;    call the n'th bios routine.
;    bc is put into the bc-register as a parameter.
;    returns whatever bios puts into the a-reg.
;
QZBIOS:
    POP    H    ;get return address
    POP    B    ;    bc
    POP    D    ;    n
    PUSH    D    ;restore stack the way it was
    PUSH    B
    PUSH    H
    LHLD    1    ;point hl at start of BIOS jump table
    DCX    H
    DCX    H
    DCX    H
    MOV    A,E    ;put index into jump table into de
    ADD    A
    ADD    E
    MVI    D,0
    MOV    E,A
    DAD    D    ;point hl at proper entry in jump table
    PUSH    H    ;push call address
    LXI    H,QZBIOS1 ;point hl at return address
    XTHL        ;push return address, get call address
    PCHL        ;call proper BIOS routine
QZBIOS1:
    MOV    L,A     ;put return code from BIOS into hl
    MVI    H,0
    RET        ;go back to small-c
#endasm

syscstat()
{
    if (bios(2,0)==255) {
        return(-1);
    }
    else {
        return(0);
    }
}

syscin()
{
    return(bios(3,0));
}

syscout(c) char c;
{
    bios(4,c);
    return(c);
}
---------- end comment out */


/* print character on the printer */

syslout(c) char c;
{
    cpm(5,c);
    return(c);
}

#asm
;
; sysend()
;
; return address of last usable memory location.
;
QZSYSEND:
    LHLD    6    ;get address of BDOS-1
    DCX    H    ;
    RET        ;return
#endasm

/* open a file */

sysopen(name,mode) char *name, *mode;
{
int file;
    if ((file=fopen(name,mode))==0) {
        return(ERR);
    }
    else {
        return(file);
    }
}

/* close a file */

sysclose(file) int file;
{
    /* fclose doesn't reliably return OK */
    fclose(file);
    return(OK);
}

/* read next char from file */

sysrdch(file) int file;
{
int c;
    if ((c=getc(file))==-1) {
        return(EOF);
    }
    else {
        return(c);
    }
}

/* write next char to file */

syspshch(c,file) char c; int file;
{
    if (putc(c,file)==-1) {
        error("disk write failed");
        return(ERR);
    }
    else {
        return(c);
    }
}

/* read one char from END of file */

syspopch(file) int file;
{
    error("syspopch() not implemented");
    return(ERR);
}

/* check file name for syntax */

syschkfn(args) char *args;
{
    return(OK);
}

/* copy file name from args to buffer */

syscopfn(args,buffer) char *args, *buffer;
{
int n;
    n=0;
    while (n< SYSFNMAX-1) {
        if (args[n]==EOS) {
            break;
        }
        else {
            buffer[n]=args[n];
            n++;
        }
    }
    buffer[n]=EOS;
}

/* move a block of n bytes down (towards HIGH addresses).
 * block starts a source and the first byte goes to dest.
 * this routine is only called from bufmovdn() as follows
 *    sysmovdn( n=to-from+1, dest=to+length, source=to);
 */

#asm
QZSYSMOVDN:
    POP    H    ;get return address
    POP    B    ;BC = source
    POP    D    ;DE = dest
    XTHL        ;HL = n, restore return address
    JMP    SYSMOVDN2    ;go enter loop
;
; this code is 15 times faster than the c-code it replaces.
SYSMOVDN1:
    LDAX    B    ;*dest-- = *source--
    STAX    D
    DCX    B
    DCX    D
    DCX    H    ;while ((n--)>0)
SYSMOVDN2:
    MOV    A,L
    ORA    H
    JNZ    SYSMOVDN1
;
    XTHL        ;HL = return address
    PUSH    H    ;restore stack
    PUSH    H
    PUSH    H
    RET        ;return
#endasm

/* move a block of n bytes up (towards LOW addresses).
 * the block starts at source and the first byte goes to dest.
 * this routine is called only from bufmovup() as follows:
 *     sysmovup( n=to-from+1, dest=from-length, source=from);
 */

#asm
QZSYSMOVUP:
    POP    H    ;get return address
    POP    B    ;BC = source
    POP    D    ;DE = dest
    XTHL        ;HL = n, save return address
    JMP    SYSMOVUP2    ;go enter loop
;
; this code is 15 times faster than the c-code it replaces.
SYSMOVUP1:
    LDAX    B    ;*dest++ = *source++
    STAX    D
    INX    B
    INX    D
    DCX    H    ;while ((n--)>0)
SYSMOVUP2:
    MOV    A,L
    ORA    H
    JNZ    SYSMOVUP1
;
    XTHL        ;HL = return address
    PUSH    H    ;restore stack
    PUSH    H
    PUSH    H
    RET        ;return
#endasm

    ;go enter loop
;
; this code is 15 times faster than the c-code it