I have an uint8 array and I need to pass the pointer of this array to a DMA, which transfers 16 bytes at once. So, the requirement is that the array address is 16 byte aligned, like 32'hxxxxxx00 - the last two address numbers to be 0. I declare a global array as follows:
u8 R00_PRO_ADDR[0x64000] __attribute__ ((aligned(16)));// 16 bytes address aligned
however, at the runtime, I see that the address of the array is 32'hxxxxxxx0. I also tried to do (aligned(128)) but get the same result.
This is specific to Vivado SDK Cortex A53
Declare an array so that the address is aligned on 16 byte boundaries
You can use the standard keyword alignas. No need to use a language extension:
alignas(16) u8 R00_PRO_ADDR[0x64000];
So, the requirement is that the array address is 16 byte aligned, like 32'hxxxxxx00 - the last two address numbers to be 0.
Your requirements are mixed. If you need this, then the address needs to be aligned on a 256 byte boundary:
alignas(256) u8 R00_PRO_ADDR[0x64000];
Note that a language implementation might not necessarily support arbitrarily strict alignments. If it doesn't, it should tell you so.