Hi, ASM fellows!
I'm stuck with a structure that includes a bitfield record. MASM doesn't seem to accept nesting of these. Here's the C structure that I want to translate into ASM:
typedef struct _X86_SELECTOR
{
union
{
struct
{
WORD wValue; // packed value
WORD wReserved;
};
struct
{
unsigned RPL : 2; // requested privilege level
unsigned TI : 1; // table indicator: 0=gdt, 1=ldt
unsigned Index : 13; // index into descriptor table
unsigned Reserved : 16;
};
};
}
X86_SELECTOR, *PX86_SELECTOR, **PPX86_SELECTOR;
I tried this:
X86_SELECTOR_RECORD RECORD RPL:2,TI:1,Index:13,Rsrvd:16
X86_SELECTOR UNION
X86_SELECTOR_RECORD <>
STRUCT
wValue WORD ? ;packed value
wReserved WORD ?
ENDS
X86_SELECTOR ENDS
PX86_SELECTOR equ X86_SELECTOR PTR
PPX86_SELECTOR equ PX86_SELECTOR PTR
but MASM recognizes only the fields .wValue & .wReserved.
If I tried to put the record's declaration inside the union, I got error messages.
If you encontered this limitation, just tell me. And if you know a workaround that's better!
Thanx in advance!
Lea
I'm stuck with a structure that includes a bitfield record. MASM doesn't seem to accept nesting of these. Here's the C structure that I want to translate into ASM:
typedef struct _X86_SELECTOR
{
union
{
struct
{
WORD wValue; // packed value
WORD wReserved;
};
struct
{
unsigned RPL : 2; // requested privilege level
unsigned TI : 1; // table indicator: 0=gdt, 1=ldt
unsigned Index : 13; // index into descriptor table
unsigned Reserved : 16;
};
};
}
X86_SELECTOR, *PX86_SELECTOR, **PPX86_SELECTOR;
I tried this:
X86_SELECTOR_RECORD RECORD RPL:2,TI:1,Index:13,Rsrvd:16
X86_SELECTOR UNION
X86_SELECTOR_RECORD <>
STRUCT
wValue WORD ? ;packed value
wReserved WORD ?
ENDS
X86_SELECTOR ENDS
PX86_SELECTOR equ X86_SELECTOR PTR
PPX86_SELECTOR equ PX86_SELECTOR PTR
but MASM recognizes only the fields .wValue & .wReserved.
If I tried to put the record's declaration inside the union, I got error messages.
If you encontered this limitation, just tell me. And if you know a workaround that's better!
Thanx in advance!
Lea
X86_SELECTOR_RECORD? ? RECORD? ? ? Rsrvd:16,Index:13,TI:1,RPL:2
X86_SELECTOR UNION
? ? X86_SELECTOR_RECORD <>
? ?
? ? STRUCT
? ? wValue WORD ?? ? ;packed value
? ? ? ? ? ? ? ? wReserved WORD ?
? ? ENDS
? ?
X86_SELECTOR ENDSFor example we have:
.data
xmp X86_SELECTOR <<11111111b,11001b,1,11b>>This is how to work with xmp as a record:
mov eax,xmp
and eax,mask X86_SELECTOR_RECORD.RPL
Thanks, k3Eahn!
I effectively used the mask operand but I hadn't realized a record was just a template for a mask and not a real structure.
By the way,
and eax, mask RPL
works all right too, since records fields must be unique among all symbols (except structures fieldnames).
I effectively used the mask operand but I hadn't realized a record was just a template for a mask and not a real structure.
By the way,
and eax, mask RPL
works all right too, since records fields must be unique among all symbols (except structures fieldnames).