DSP 56001 arccos -- ERRATUM

Thread View: comp.dsp

1 messages

[T] Back to Threads [V] Tree View [G] Group Articles

1 total messages Started by Avery Wang Sat, 05 Sep 1992 16:03

#641

Author: Avery Wang
Date: Sat, 05 Sep 1992 16:03

44 lines
1811 bytes

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

Thread Navigation

This is a paginated view of messages in the thread with full content displayed inline.

Messages are displayed in chronological order, with the original post highlighted in green.

Use pagination controls to navigate through all messages in large threads.

Back to All Threads