Re: Atomic operations in Obj-C?
Re: Atomic operations in Obj-C?
- Subject: Re: Atomic operations in Obj-C?
- From: Nathan Day <email@hidden>
- Date: Thu, 16 Jan 2003 00:51:10 +1030
There are some under PCI card service, though they are defined as a
part of PCI card service they can be used generally.
The Driver Services Library provides several 32-, 16-, and 8-bit
atomic memory operations for use by device drivers. These routines take
logical address pointers and ensure that the operations are atomic with
respect to all devices (for example, other processors and DMA engines)
that participate in the coherency architecture of the Power Macintosh
system.
IMPORTANT
Memory locations used by these operations must be long word aligned; if
they are stored in a structure, you should use the compiler directive
#pragma options align=power.
Boolean CompareAndSwap( long oldValue, long newValue, long *Value );
SInt32 IncrementAtomic( SInt32 *value );
SInt32 DecrementAtomic( SInt32 *value );
SInt32 AddAtomic( SInt32 amount, SInt32 *value );
UInt32 BitAndAtomic( UInt32 mask, UInt32 *value );
UInt32 BitOrAtomic( UInt32 mask, UInt32 *value );
UInt32 BitXorAtomic( UInt32 mask, UInt32 *value );
SInt16 IncrementAtomic16( SInt16 * value );
SInt16 DecrementAtomic16( SInt16 * value );
SInt16 AddAtomic16( SInt32 amount, SInt16 * value );
UInt16 BitAndAtomic16( UInt32 mask, UInt16 * value );
UInt16 BitOrAtomic16( UInt32 mask, UInt16 * value );
UInt16 BitXorAtomic16( UInt32 mask, UInt16 * value );
SInt8 IncrementAtomic8( SInt8 * value );
SInt8 DecrementAtomic8( SInt8 * value );
SInt8 AddAtomic8( SInt32 amount, SInt8 *value );
UInt8 BitAndAtomic8( UInt32 mask, UInt8 *value );
UInt8 BitOrAtomic8( UInt32 mask, UInt8 *value );
UInt8 BitXorAtomic8( UInt32 mask, UInt8 *value );
DESCRIPTION
The atomic routines perform various operations on the memory address
specified by value :
The CompareAndSwap routine compares the value at the specified
address with oldValue. The value of newValue is written to the
specified address only if oldValue and the value at the specified
address are equal. CompareAndSwap returns true if newValue is written
to the specified address; otherwise, it returns false. A false return
value does not imply that oldValue and the value at the specified
address are not equal; it only implies that CompareAndSwap did not
write newValue to the specified address.
IncrementAtomic increments the value by 1 and DecrementAtomic
decrements it by 1. These functions return the value as it was before
the change.
AddAtomic adds the specified amount to the value at the specified
address and returns the result.
BitAndAtomic performs a logical and operation between the bits of the
specified mask and the value at the specified address, returning the
result. Similarly, BitOrAtomic performs a logical OR operation and
BitXorAtomic performs a logical XOR operation.
EXECUTION CONTEXT
The atomic operation routines may be called from task level, secondary
interrupt level, or hardware interrupt level.
Bit Operations
Boolean TestAndSet( UInt32 bit, UInt8 *startAddress );
Boolean TestAndClear( UInt32 bit, UInt8 *startAddress );
--> bit The bit number in the range 0 through 7.
--> startAddress The address of the byte in which the bit is located.
DESCRIPTION
TestAndSet sets and TestAndClear clears a single bit in a byte at a
specified address. They return true if the bit was already set or
cleared respectively and false otherwise.
EXECUTION CONTEXT
TestAndSet and TestAndClear may be called from task level, secondary
interrupt level, or hardware interrupt level.
On Wednesday, January 15, 2003, at 07:31 PM, Pierre-Olivier Latour
wrote:
Where can you find some routines to do atomic operations in the
Cocoa/Obj-C/*nix headers?
I found ones in the IOKit but only for the use inside the kernel :(
Nathan Day
http://homepage.mac.com/nathan_day/
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