Texas Instruments TMS320C80, Руководство пользователя

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Prototyping Code Using Linker Command Files
3-18 TMS320C80 to TMS320C82 Software Compatibility User’s Guide
Example 3–9.Assembly Language Function to Calculate the Dot Product of Two Vectors
a_addr .set d1 ; pointer to A[] passed in d1
b_addr .set d2 ; pointer to B[] passed in d2
vect_size .set d3 ; vector size is passed in d3
dot_product .set d5 ; the dot product of A and B is
; returned in d5.
A .reg d ; ppca determines the registers
B .reg d ; these variables will be assigned to.
prod .reg d
La_A_ptr .reg la
Ga_B_ptr .reg ga
.lock d6, d7, a4, a12 ; tell ppca not to use
; these registers
.entry a_addr, b_addr, vect_size ; tell ppca that registers
; are live on entry (these
; are the arguments passed
; from the C calling function).
.system $dot_product ; define function entry point
.system _dot_product ; so that it is visible
; to both MP and PP C.
$dot_product:
_dot_product:
La_A_ptr = a_addr
; initialize a local address
; register to vector A.
Ga_B_ptr = b_addr ; initialize global address
; register to vector B.
lrse2 = vect_size – 1 ; Use the fast initialization
; form to set up a single
; instruction loop. The PP
; executes the instruction
; at DOT_PROD_LOOP vect_size
; times.
prod = 0 ; clear prod.
|| A =h *L+ ; load first element of A,
; using the local port
; and postincrement A’s
; pointer.
dot_product = 0 ; clear dot_product
|| B =h *G+ ; load first element of B,
; using the global port
; and postincrement B’s
; pointer.
DOT_PROD_LOOP:
prod = A * B
; calculate the product of
; A and B
|| dot_product=dot_prod ; calculate sum of products
|| B =h *G+ ; load next B element (global port)
|| A =h *L+ ; load next A element (local port)
.cjump DOT_PROD_LOOP
; tell ppca that the code conditionally
; loops to DOT_PROD_LOOP.
br = iprs ; return to calling function.
dot_product = dot_p prod ; calculate last sum.
nop
.uexit ; tell ppca that this is the end of
; this function.