; inprod_asm_func.asm 
; Multiply two arrays. Called from inner_prod_asm.c
; A4=x address,B4=y address,A6=count(size of array),B3=return address
        
        .def    _inprod_asm_func                ; inner product function
.text                                           ; text section
_inprod_asm_func        MV      A6,A1           ; move loop count to A1
                ZERO            A7              ; init A7 for accumulation
LOOP            LDH             *A4++,A2        ; A2=(x). A4 as address pointer
                LDH             *B4++,B2        ; B2=(y). B4 as address pointer
                NOP     4                       ; 4 delay slots for LDH
                MPY     .M1x    B2,A2,A3        ; A3 = x * y
                NOP                             ; 1 delay slot for MPY  
                ADD             A3,A7,A7        ; sum of products in A7
                SUB             A1,1,A1         ; decrement loop counter
    [A1]        B       LOOP                    ; branch back to loop til A1=0
                NOP     5                       ; 5 delay slots for branch
                MV              A7,A4           ; A4=result A4=return register
                B               B3              ; ret from func to addr in B3
                NOP     5                       ; 5 delay slots for branch