Aligning structure members
Author
Hey,
I need to align structure members to 16 byte boundaries. I tried
struct Foo {
__declspec(align(16)) volatile unsigned int* data0;
__declspec(align(16)) volatile unsigned int* data1;
__declspec(align(16)) volatile unsigned int* data2;
__declspec(align(16)) volatile unsigned int* data3;
};
Though, the members were aligned to 8 byte boundaries.
I was thinking of doing this
__declspec(align(16)) struct Foo {
volatile unsigned int* data0;
uint32 padding0;
uint32 padding1;
volatile unsigned int* data1;
uint32 padding2;
uint32 padding3;
};
Though, that assumes pointers are 8 bytes so I'd have to make defines to determine how much padding are between each variable per platform.
Any other ideas?
I'm only having this problem with visual studio not other compilers :(
-= Dave
Strange. Under MVC2008:
That failing to work, there's always the possibility of using a union. Perhaps:
struct Foo { __declspec( align( 16 ) ) volatile unsigned int* data0; __declspec( align( 16 ) ) volatile unsigned int* data1; __declspec( align( 16 ) ) volatile unsigned int* data2; __declspec( align( 16 ) ) volatile unsigned int* data3;};int main(){ Foo foo; printf("%d %d\n", sizeof(Foo), sizeof(foo)); printf("%x %d\n", &foo.data0, offsetof(Foo, data0)); printf("%x %d\n", &foo.data1, offsetof(Foo, data1)); printf("%x %d\n", &foo.data2, offsetof(Foo, data2)); printf("%x %d\n", &foo.data3, offsetof(Foo, data3)); return 0;}64 6412ff30 012ff40 1612ff50 3212ff60 48That failing to work, there's always the possibility of using a union. Perhaps:
struct DataPtr { union { volatile int * data; char padding[16]; } value; volatile int * operator->() { return value.data; } volatile int * operator*() { return value.data; }};struct Foo2 { DataPtr data0; DataPtr data1; DataPtr data2; DataPtr data3;};This topic is closed to new replies.
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