On the c6000, we need to align and pad structures to 64 or 128 bytes (depending on the type of memory) in order to implement software driven cache coherence.
The alignment can be accomplished with #pragma DATA_ALIGN(). However, this doesn't cause any padding at the end of the structure. The padding is required in order to prevent the linker from putting anything else in the last cache line of the structure.
One way to add the padding is to put the desired structure into another structure eg:
typedef struct {
. . .
} struct_to_pad;
typedef struct {
struct_to_pad s;
char pad[128 - (sizeof(struct_to_pad) & 0x7f)]
} padded_struct;
The above is messy because it requires modifying all the code that references the structure to either use a pointer indirection or to insert the struct.s. It is also messy because, since pad[0] is illegal, there is no way to make "pad" go away if it turns out the structure already has an aligned length thus it wastes more memory than required.
Another way to achieve the padding is to put each such structure in a #pragma DATA_SECTION, and place each into its own output section. This is messy due to plethora of output sections.
Are there any cleaner ways to achieve the padding?
