/*
SG C Tools 1.0

(C) 1993 Steve Goldsmith
All Rights Reserved

VDCASM.C is in-line Z80 Assembler code to speed up invdc() and outvdc().
I encountered a compiler lock up tring to optimize (-O) VDC.C with this code.
I used C -O -C VDC.C to compile.  Works fine without -O, go figure?  Just
replace the code in VDC.C with the code below.  If you can figure out why this
is bombing the optimizer let me know!  Even without -O the Assembler code is
faster than inp() and outp()!

Compiled with HI-TECH C 3.09 (CP/M-80).
*/

uchar invdc(uchar RegNum)
{

/* in-line assembler to set vdc reg to read and wait for status bit 7 */

#asm
        ld      a,(ix+6)
        ld      bc,0d600h
        out     (c),a
1:
        in      a,(c)
        bit     7,a
        jr      z,1b
#endasm

  return(inp(vdcDataReg));                    /* read register */
}

void outvdc(uchar RegNum, uchar RegVal)
{

/* in-line assembler to set vdc reg to write, wait for status bit 7 and */
/* write new value to reg */

#asm
        ld      a,(ix+6)
        ld      bc,0d600h
        out     (c),a
1:
        in      a,(c)
        bit     7,a
        jr      z,1b
        ld      a,(ix+8)
        inc     bc
        out     (c),a
#endasm

}