Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!rochester!pt.cs.cmu.edu!vi.ri.cmu.edu!rwb
From: rwb@vi.ri.cmu.edu (Bob Berger)
Newsgroups: comp.sys.next
Subject: DSP help needed
Keywords: off chip memory
Message-ID: <5262@pt.cs.cmu.edu>
Date: 20 Jun 89 20:18:27 GMT
Organization: Carnegie-Mellon University, CS/RI
Lines: 76



I need to write some dsp routines that process arrays of data.
I wrote a simple test program which reads an array from the host
interface into DSP memory, then writes the array back to the host
with each element shifted. The program works when I put the array
into the DSP's on chip memory, but fails when I try to use the off chip
memory at $2000. When it fails, all of the elements returned are
copies of the last element written to the memory, as if the memory
were not enabled or something.

What am I doing wrong?

Here's my code:

; array56k.asm  DSP bootstrap program that reads an array,
; right shifts each element, and sends the array back to the host

		org p:0 
reset	jmp >rcv_cnt

	dup $40-2	; output must be a contiguous segment
	nop
	endm

	org p:$40	;  starting address

rcv_cnt jclr #0,x:$FFE9,rcv_cnt	; wait for data from host 
	move x:$FFEB,R0		; RO = count
	
	move #$2000,R1		; R1 = array address in external memory
	
	do R0,end_rcv
rcv_dat jclr #0,x:$FFE9,rcv_dat	; wait for data from host
	move x:$FFEB,A1		; get word from host
	move A1,x:(R1)+		; put it in external memory
end_rcv
	
	move #$2000,R1		; R1 = array address in external memory

	do R0,end_xmt
	move x:(R1)+,A1		; get word from memory
	LSR A			; right-shift one place
xmt_dat jclr #1,x:$FFE9,xmt_dat	; wait for host ready
	move A1,x:$FFEB		; send shifted word to host 
end_xmt

	jmp rcv_cnt
	
	end $40
	


#include <dsp/dsp.h> 

int count = 5;
int data[] = {2,4,6,8,10};

main()
{ 
    int i;

    DSPBootFile("array56k"); 

    DSPPutTX(count);
    DSPPutTXArray(data,count);
    DSPGetRXArray(data,count);
	
    for (i = 0; i < count; i++)
	printf("%d ",data[i]);
    printf("\n");

    DSPClose(); 
}


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