🚀 go-pugleaf

Hi DSP hackers-

Thanks to mlelstv@specklec.mpifr-bonn.mpg.de for pointing out that my posting
was rather nonsense.  What happened was that I grabbed the wrong file and
posted that instead of the correct (working and compilable) version of the
arccos macro.  Here is the correct version for those who are interested.

=======================================================================
;   arccos.asm
;   Calculates the arc-cosine of the input to 8 bits.
;   The output is between 0 and +127 and is in a
;
;   Copyright! February 20,1992
;   Free for non-profit usage
;
;   Avery Wang                         
;   Ruhr-Uni-Bochum
;   Institut fuer Neuroinformatik
;   ND03, Postfach 102148
;   W-4630 Bochum
;   Germany
;   avery@neuroinformatik.ruhr-uni-bochum.de  or
;   awang@isl.stanford.edu

; uses the Sine-ROM and simply does a table lookup.
; input and output are in a
; uses a,b,x0,y0,r6,r7,n7
arccos macro
    move #$140,r7           ;offset
    move #$40,n7            ;guess
    move n7,b
    do #7,_arccos_loop
        lua (r7)+n7,r6                  ;save guess
        nop
        asr b       a,x0    y:(r6),y0   ;make increment smaller, lookup cosine
        cmp y0,a    b,n7
        tlt x0,a    r6,r7  ;dummy move, if arg>table value, keep old guess
        nop
_arccos_loop
    move r7,a
    move #$140,y0
    sub  y0,a                           ;result is here

    endm