Fredrik Norings DSP info page 4 (5)
DSP

DSP 56001 Host Communication

DSP main page,
DSP System calls.
DMA System calls.
DSP Host Communication Example.
DMA Handshaked Communication Example.

This example illustrates a typical DSP Host communication program.

; DSP Host Port IO
: Author: Fredrik Noring, 1994

M_HSR   EQU     $FFE9        ; Host Status Register
M_HRX   EQU     $FFEB        ; Host Receive Data Register
M_HTX   EQU     $FFEB        ; Host Transmit Data Register

          org    p:$0
          jmp    <start

          org    p:$40
start     jsr    <Host_get   ; Receive Host data
          move   #0.27,A     ; Move value to the 56-bits A register
          move   #0.31415,y0 ; Move value to the 24-bits y0 register
          mac    x0,y0,A     ; Multiply x0 and y0 and accumulate to A
          move   A,x0        ; Move the A1 portion of A to x0
          jsr    <Host_send  ; Send Host data

          jmp    <start      ; Continue

; Host I/O routines.
Host_get  jclr    #0,X:<<M_HSR,<Host_get
          movep   X:<<M_HRX,x0  ; Move 24-bits Host data to x0
          rts
Host_send jclr    #1,X:<<M_HSR,<Host_send    ; 
          movep   x0,X:<<M_HTX  ; Move x0 to 24-bits Host data
          rts