Using inline assembler
I'm a bit new to the inline assembler, I'm trying to use the `movdqu`
operation to move a 128 bit double quadword from a pointer location into
another location like this:
align(16) union __m128i { ubyte[16] data };
void store(__m128i* src, __m128i* dst) {
asm { movdqu [dst], src; }
}
The compiler complains about a bad type/size of operands 'movdqu', but
these two data segments are 16 byte align so they should be in an XMM#
register? Is there something I'm missing here?
Re: Using inline assembler
On Thursday, 9 October 2014 at 12:37:20 UTC, Etienne wrote:
I'm a bit new to the inline assembler, I'm trying to use the
`movdqu` operation to move a 128 bit double quadword from a
pointer location into another location like this:
align(16) union __m128i { ubyte[16] data };
void store(__m128i* src, __m128i* dst) {
asm { movdqu [dst], src; }
}
The compiler complains about a bad type/size of operands
'movdqu', but these two data segments are 16 byte align so
they should be in an XMM# register? Is there something I'm
missing here?
I know virtually nothing about SSE, but you can't move directly
from memory to memory, can you? You need go through a register,
no?
This compiles:
align(16) union __m128i { ubyte[16] data; } /* note the position
of the semicolon */
void store(__m128i* src, __m128i* dst) {
asm
{
movdqu XMM0, [src]; /* note: [src] */
movdqu [dst], XMM0;
}
}
Re: Using inline assembler
On 2014-10-09 8:54 AM, anonymous wrote:
This compiles:
align(16) union __m128i { ubyte[16] data; } /* note the position
of the semicolon */
void store(__m128i* src, __m128i* dst) {
asm
{
movdqu XMM0, [src]; /* note: [src] */
movdqu [dst], XMM0;
}
}
Yes, this does compile, but the value from src never ends up stored in dst.
void main() {
__m128i src;
src.data[0] = 255;
__m128i dst;
writeln(src.data); // shows 255 at offset 0
store(src, dst);
writeln(dst.data); // remains set as the initial array
}
http://x86.renejeschke.de/html/file_module_x86_id_184.html
Is this how it's meant to be used?
Re: Using inline assembler
Maybe someone can help with the more specific problem. I'm translating a crypto engine here: https://github.com/etcimon/botan/blob/master/source/botan/block/aes_ni/aes_ni.d But I need this to work on DMD, LDC and GDC. I decided to write the assembler code directly for the functions in this module: https://github.com/etcimon/botan/blob/master/source/botan/utils/simd/xmmintrin.d If there's anything someone can tell me about this, I'd be thankful. I'm very experienced in every aspect of programming, but still at my first baby steps in assembler.
Re: Using inline assembler
On Thursday, 9 October 2014 at 13:29:27 UTC, Etienne wrote:
On 2014-10-09 8:54 AM, anonymous wrote:
This compiles:
align(16) union __m128i { ubyte[16] data; } /* note the
position
of the semicolon */
void store(__m128i* src, __m128i* dst) {
asm
{
movdqu XMM0, [src]; /* note: [src] */
movdqu [dst], XMM0;
}
}
Yes, this does compile, but the value from src never ends up
stored in dst.
void main() {
__m128i src;
src.data[0] = 255;
__m128i dst;
writeln(src.data); // shows 255 at offset 0
store(src, dst);
writeln(dst.data); // remains set as the initial array
}
http://x86.renejeschke.de/html/file_module_x86_id_184.html
Is this how it's meant to be used?
I'm out of my knowledge zone here, but it seems to work when you
move the pointers to registers first:
void store(__m128i* src, __m128i* dst) {
asm
{
mov RAX, src;
mov RBX, dst;
movdqu XMM0, [RAX];
movdqu [RBX], XMM0;
}
}
Re: Using inline assembler
On 2014-10-09 9:46 AM, anonymous wrote:
I'm out of my knowledge zone here, but it seems to work when you
move the pointers to registers first:
void store(__m128i* src, __m128i* dst) {
asm
{
mov RAX, src;
mov RBX, dst;
movdqu XMM0, [RAX];
movdqu [RBX], XMM0;
}
}
Absolutely incredible! My first useful working assembler code. You save
the day. Now I can probably write a whole SIMD library ;)
