ex7p1qxx.asm

用于DSK5416的程序

;----------------------------------------------------------------------------
; Program Name: ex7p1Qxx.asm
;
; Description:  This is an example to show how to multiply numbers 
;               represented using Q-notation. It implements the following: 
;
;               N1xN2 = N1 * N2
;
;               where 
;               N1 and N2 are 16-bit numbers in Q15 notation
;               N1xN2 is the 16-bit result in Q15 notation
;
; Author:       Avtar Singh, SJSU
;-----------------------------------------------------------------------------


                .mmregs                 ; memory-mapped registers

                .data                   ; sequential locations
N1:             .word   4000h           ; N1 = 0.5 (Q15 number)
N2:             .word   2000h           ; N2 = 0.25 (Q15 number)
N1xN2:          .space  10h             ; space for N1 x N2 


                .text
                .ref    _c_int00

                .sect   ".vectors"
RESET:          b       _c_int00        ; Reset vector
                nop
                nop


_c_int00:
                stm     #N1, AR2        ; AR2 points to N1
                ld      *AR2+, T        ; T reg = N1
                mpy     *AR2+, A        ; A = N1 * N2 in Q30 notation
                add     #1, 14, A       ; round the result
                sth     A, 1, *AR2      ; save N1 * N2 as Q15 number
                nop
                nop
				
                .end