Statement

A statement is a group of expressions and/or statements that you design to carry out a task or an action. Statements are two-sided - that is, they either perform tasks or do not perform tasks.

Return

Return is used to end the execution of the function call and “returns” the result (value of the expression following the return keyword) to the caller.

@S.prim_func
def add_one(x: S.int32) -> S.int32:
    return x + 1

@S.prim_func
def test_stmt(a: S.int32, out: S.int32):
    out = add_one(a)

Assignment

Assignment is used to assign the value to the specified variable.

@S.prim_func
def test_stmt(a: S.int32, out: S.int32):
    b, d = a + 1, a
    out = b + d

In this case, there are 3 variables assigned values.

Allocate

Allocate is used to allocate memory or resources, similar to the “new” statement in C++, requires three arguments: shape, dtype and scope.

shape. The shape of data in the content of the buffer.
dtype. The data type in the content of the buffer.
scope. The storage scope of data in the content of the buffer.

    @S.prim_func
    def test_stmt(a: S.int32, out: S.int32):
        lsram = S.alloc_buffer((1024,), "int32", scope="lsram")
        S.dma_memset(lsram, value=1, num=1024)
        out = lsram[0] + lsram[1]

In this case, we allocate a buffer on local SRAM with shape (1024,) and data type int32.

Buffer Match

The buffer match function, matches a buffer from an address with the given shape.

pointer. The address of a buffer.
shape. The specific shape of the buffer that you want to match.

@S.prim_func
def func(A: S.ptr("int8", "global"), B: S.ptr("int8", "global"), h: S.int32, w: S.int32):
    a = S.match_buffer(A, shape=(h, w))
    b = S.match_buffer(B, shape=(w, h))
    for i, j in S.grid(h, w):
        b[j, i] = a[i, j]

In this case, the A and B are pointers of the address. We use S.match_buffer to match 2-D buffer a and b. Then we can access data by subscript.

For

@S.prim_func
def test_stmt(a: S.int32, out: S.int32):
    out = 0
    for idx in range(a):
        out += idx

In this case, “for” is a statement defining the iteration step. In addition, “while” is also a form of loop statement.

IfThenElse

In this case, “if” is a conditional statement.

@S.prim_func
def test_stmt(a: S.int32, out: S.int32):
    if a == 1:
        out = 10
    else:
        out = 20

It decides the direction (control flow) of the flow of program execution.