Description
The DISAGGREGATE pragma lets you deconstruct a struct variable into its individual elements. The number and type of elements
created are determined by the contents of the struct itself.
Syntax
Place the pragma in the C source within the boundaries of the region, function, or loop.
#pragma HLS disaggregate variable=<variable>Options
Where:
-
variable=<variable>: Specifies the struct variable to disaggregate.
Example 1
The following example shows the struct variable a in function top will be disaggregated:
#pragma HLS disaggregate variable=aExample 2
Disaggregated structs can be addressed in your code by the using standard C/C++ coding style as shown below. Notice the different methods for accessing the pointer element (a) versus the reference element (c);
struct SS
{
int x[N];
int y[N];
};
int top(SS *a, int b[4][6], SS &c) {
#pragma HLS disaggregate variable = a
#pragma HLS interface s_axilite port = a->x
#pragma HLS interface s_axilite port = a->y
// Following is now supported
#pragma HLS disaggregate variable = c
#pragma HLS interface ap_memory port = c.x
#pragma HLS interface ap_memory port = c.y
Example 3
The following example shows the Dot
struct containing the RGB struct as an element. If you
apply the DISAGGREGATE pragma to variable Arr, then only
the top-level Dot struct is disaggregated.
struct Pixel {
char R;
char G;
char B;
};
struct Dot {
Pixel RGB;
unsigned Size;
};
#define N 1086
void DUT(Dot Arr[N]) {
#pragma HLS disaggregate variable=Arr
...
}
If you want to disaggregate the whole struct, Dot and RGB, then you can assign the
DISAGGREGATE pragma as shown below.
void DUT(Dot Arr[N]) {
#pragma HLS disaggregate variable=Arr->RGB
...
}
void DUT(char Arr_RGB_R[N], char Arr_RGB_G[N], char Arr_RGB_B[N], unsigned Arr_Size[N]) {
#pragma HLS disaggregate variable=Arr->RGB
...
}