bit-fields

I was wondering if there is a GCC C Compiler directive that allows me to determine the bit order for packing of a structure? Something to the likes of: #pragma bit_order left The rationale for such a need is that I have the following structure: struct { union { unsigned char BYTE; struct { unsigned char B0: 1; unsigned char B1: 1; unsigned char B2: 1; unsigned char B3: 1; unsigned char B4: 4; }BIT; }ITEM; } myStruct; With this structure, I would like the compiler to pack it this way: Bit order: | 7 6 5 4 3 2 1 0 | Label: |B0 B1 B2 B3 B4 B5 B6 B7 | Rather than how GCC does it: Bit order: | 7 6

I have a struct with bit-fields (totally 32 bit width) and I have a 32-bit variable. When I try to assign the variable value to my struct, I got an error: error: conversion from ‘uint32_t {aka unsigned int}’ to non-scalar type ‘main()::CPUID’ requested. struct CPUIDregs { uint32_t EAXBuf; }; CPUIDregs CPUIDregsoutput; int main () { struct CPUID { uint32_t Stepping : 4; uint32_t Model : 4; uint32_t FamilyID : 4; uint32_t Type : 2; uint32_t Reserved1 : 2; uint32_t ExtendedModel : 4; uint32_t ExtendedFamilyID : 8; uint32_t Reserved2 : 4; }; CPUID CPUIDoutput = CPUIDregsoutput.EAXBuf; Do you have

I have an int32 attribute in a Core Data database. I use this int as an enum bit field. Is it possible to create a NSPredicate to query items based on the binary value of this int ? Something like @"bitFieldAttribute & 0x0001" ? I'm also wondering if this is possible with a binary typed attribute ? NSPredicate can handle it, but I'm not sure if CoreData will accept it as a valid predicate for execution on a data store. It might have trouble converting the bitwise operator into a SQL query (if you're using a SQLite backing store). You'll just have to try it. The syntax, however, is just what

I have four flags Current = 0x1 Past = 0x2 Future = 0x4 All = 0x7 Say I receive the two flags Past and Future ( setFlags(PAST | FUTURE) ). How can I tell if Past is in it? Likewise how can I tell that Current is not in it? That way I don't have to test for every possible combination. If you want all bits in the test mask to match: if((value & mask) == mask) {...} If you want any single bit in the test mask to match: if((value & mask) != 0) {...} The difference is most apparent when you are testing a value for multiple things. To test for exclusion: if ((value & mask) == 0) { } First of all -