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 | Posted by d-bugmail |  Permalink Reply |
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d-bugmail 
| http://d.puremagic.com/bugzilla/show_bug.cgi?id=13
Summary: Difficulty accessing byte and short inout parameters
from inline asm
Product: D
Version: 0.148
Platform: PC
OS/Version: Windows
Status: NEW
Severity: normal
Priority: P2
Component: DMD
AssignedTo: braddr@puremagic.com
ReportedBy: sean@f4.ca
I'm having problems manipulating inout function parameters within asm blocks if those parameters are not 32 bits in size. Since inout parameters are pointers, I first tried the obvious method:
C:\code\d>type test.d
import std.c.stdio;
void fn( inout byte val )
{
asm
{
mov EAX, val;
inc [EAX];
}
}
void main()
{
byte b;
printf( "%i\n", b );
fn( b );
printf( "i%\n", b );
}
C:\code\d>dmd test
test.d(7): bad type/size of operands 'mov'
C:\code\d>
When that didn't work, I tried simply adding a "byte ptr" descriptor to the variable, but got similar results:
C:\code\d>type test.d
import std.c.stdio;
void fn( inout byte val )
{
asm
{
mov EAX, byte ptr val;
inc [EAX];
}
}
void main()
{
byte b;
printf( "%i\n", b );
fn( b );
printf( "%i\n", b );
}
C:\code\d>dmd test
test.d(7): bad type/size of operands 'mov'
C:\code\d>
So finally I thought that perhaps the assembler was outsmarting me and treating 'val' like an actual value instead of a pointer:
C:\code\d>type test.d
import std.c.stdio;
void fn( inout byte val )
{
asm
{
lea EAX, val;
inc [EAX];
}
}
void main()
{
byte b;
printf( "%i\n", b );
fn( b );
printf( "%i\n", b );
}
C:\code\d>dmd test
C:\bin\dmd\bin\..\..\dm\bin\link.exe test,,,user32+kernel32/noi;
C:\code\d>test
0
0
C:\code\d>
But the above result makes it clear that it does not, as the second value shoule be 1.
Is there any way to force the inline assembler to treat 'val' as a pointer without declaring a temporary? And is this something that can be fixed? I know I could write naked asm, but I don't consider that a viable option
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