Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: pthread_mutex_lock in ANSI C vs using Atomic builtins of GCC
Top Forums Programming pthread_mutex_lock in ANSI C vs using Atomic builtins of GCC Post 302448266 by sehang on Wednesday 25th of August 2010 03:39:54 PM
Old 08-25-2010
pthread_mutex_lock in ANSI C vs using Atomic builtins of GCC
I have a program which has 7-8 threads, and lots of shared variables; these variables (and also they may not the primitive type, they may be enum or struct ), then they may read/write by different threads at the same time.

Now, my design is like this,

Code:
typedef unsigned short int UINT16;
struct STRUCT {
  UINT16 uint16;
  int INT;
}
enum ENUM = { ... };

/* Shared Variables. */
struct STRUCT Shared_VariableA;
enum ENUM Shared_VariableB;

UINT16 GetVA () {
    pthread_mutex_lock( &_L_LOCK );
        UINT16 TMP = Shared_VariableA.uint16;
    pthread_mutex_lock( &_L_LOCK );
    return TMP;
}

void SetVA ( UINT16 in ) {
     pthread_mutex_lock( &_L_LOCK );
         Shared_VariableA.uint16 = in;
     pthread_mutex_lock( &_L_LOCK );
 }

Is it enough to guarantee that only a thread can write/read shared variables at the same time?

How about the following method? Same?
From the reference : Techie Stuff Atomic Operations

Code:
/* Initialization. */
atomic_t uint16 = ATOMIC_INIT ( 0 );

UINT16 GetVA () {
         UINT16 TMP = atomic_read( &uint16 );  /* Force convert 'int' to UINT16 since atomic_read() returns an int (32 bits). */
        return TMP;
 }
 
 void SetVA ( UINT16 in ) {
       atomic_set( &uint16,in );
  }

Whether getVA() will return an arbitrary value when SetVA() is running by other threads?
 

9 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Convert file from Unix - ANSI to PC - ANSI

Hi, I am creating a file in Unix using a shell script. The file is getting created in the Unix - ANSI format. My requirement is to convert it to the PC - ANSI format. Can anyone tell me how to do this? Thanks, Sunil (0 Replies)
Discussion started by: ssmallya
0 Replies

2. Programming

pthread_rwlock_lock vs pthread_mutex_lock

I have been wondering what the difference between pthread_rwlock_lock and pthread_mutex_lock is. Both these routines acquire an exclusive rw lock on an enclosed region. So I performed a simple experiment in which I execute both these routines multiple times in a loop. Here are the results:... (1 Reply)
Discussion started by: kmehta
1 Replies

3. Programming

Interesting issue with pthread_mutex_lock and siglongjmp in AIX 5.3 (and no other OS)

Executive summary: Code (posted below) cores in AIX 5.3, despite being compiled and run successfully on several other operating systems. Code is attempting to verify that pthread_mutex_lock can be successfully aborted by siglongjmp. I do not believe this is an unreasonable requirement. If... (1 Reply)
Discussion started by: DreamWarrior
1 Replies

4. Shell Programming and Scripting

program name and function name builtins

Hi Is there a way to get the program/script name or function name usng built ins. Like in many languages arg holds the program name regards (2 Replies)
Discussion started by: xiamin
2 Replies

5. Programming

why the implementatoin of Bakery algorithm in ANSI C does not work in ANSI C

I follow the description of wiki (Lamport's bakery algorithm - Wikipedia, the free encyclopedia), then implement that algorithm in C, but it doesn't work, Starving is still here, is the implementation worry? Only print out: Thread ID: 0 START! Thread ID: 0 END! Thread ID: 0 START!... (2 Replies)
Discussion started by: sehang
2 Replies

6. UNIX for Advanced & Expert Users

Writing Custom Builtins for KSH93

I am looking to create some ksh93 extensions using the custom builtin feature. I can successfully create a builtin function, load it using the builtin -f command and get an output. However, I want to get/set values of KSH variables from within my built-in. For example, lets say I am creating... (2 Replies)
Discussion started by: a_programmer
2 Replies

7. UNIX for Dummies Questions & Answers

Why does /bin contain binaries for builtins?

Why do shell builtins like echo and pwd have binaries in /bin? When I do which pwd, I get the one in /bin. that means that I am not using the builtin version? What determines which one gets used? Is the which command a definitive way to determine what is being run when I enter pwd? (16 Replies)
Discussion started by: glev2005
16 Replies

8. Programming

Using ANSI color codes in gcc compiled program

I have put some yellow color codes and works well. I call the funstion using print_usage(stderr, 0); I would like to know if there is any way, to store the ansi color codes in variables and then call them inside fprintf. Or have a format followed by the strings I want to output. ... (5 Replies)
Discussion started by: kristinu
5 Replies

9. UNIX for Dummies Questions & Answers

Shell and bash builtins...

Not sure if this is the right forum but I have collated a listing of shell and bash builtins. Builtins is a loose word and may include the '/bin' drawer/folder/directory but NOT any others in the path list. In the case of my Macbook Pro, OSX 10.7.5 the enabled internals is also listed... ... (1 Reply)
Discussion started by: wisecracker
1 Replies

LEARN ABOUT SUSE

tiffsetfield

TIFFSetField(3TIFF)													       TIFFSetField(3TIFF)

NAME

       TIFFSetField, TIFFVSetField - set the value(s) of a tag in a TIFF file open for writing

SYNOPSIS

       #include <tiffio.h>

       int TIFFSetField(TIFF *tif, ttag_t tag, ...)

       #include <stdarg.h>

       int TIFFVSetField(TIFF *tif, ttag_t tag, va_list ap)

DESCRIPTION

       TIFFSetField  sets  the value of a field or pseudo-tag in the current directory associated with the open TIFF file tif.	(A pseudo-tag is a
       parameter that is used to control the operation of the TIFF library but whose value is not read or written to the underlying file.)  To set
       the  value  of  a field the file must have been previously opened for writing with TIFFOpen(3TIFF); pseudo-tags can be set whether the file
       was opened for reading or writing.  The field is identified by tag, one of the values defined in the include file tiff.h (see also the  ta-
       ble  below).  The actual value is specified using a variable argument list, as prescribed by the stdarg(3) interface (or, on some machines,
       the varargs(3) interface.)

       TIFFVSetField is functionally equivalent to TIFFSetField except that it takes a pointer to a variable argument list.  TIFFVSetField is use-
       ful for writing routines that are layered on top of the functionality provided by TIFFSetField.

       The  tags understood by libtiff, the number of parameter values, and the expected types for the parameter values are shown below.  The data
       types are: char* is null-terminated string and corresponds to the ASCII data type; uint16  is  an  unsigned  16-bit  value;  uint32  is	an
       unsigned 32-bit value; uint16* is an array of unsigned 16-bit values.  void* is an array of data values of unspecified type.

       Consult the TIFF specification for information on the meaning of each tag.

       Tag Name 		       Count  Types		 Notes
       TIFFTAG_ARTIST		       1      char*
       TIFFTAG_BADFAXLINES	       1      uint32
       TIFFTAG_BITSPERSAMPLE	       1      uint16		 -
       TIFFTAG_CLEANFAXDATA	       1      uint16
       TIFFTAG_COLORMAP 	       3      uint16*		 1<<BitsPerSample arrays
       TIFFTAG_COMPRESSION	       1      uint16		 -
       TIFFTAG_CONSECUTIVEBADFAXLINES  1      uint32
       TIFFTAG_COPYRIGHT	       1      char*
       TIFFTAG_DATETIME 	       1      char*
       TIFFTAG_DOCUMENTNAME	       1      char*
       TIFFTAG_DOTRANGE 	       2      uint16
       TIFFTAG_EXTRASAMPLES	       2      uint16,uint16*	 - count & types array
       TIFFTAG_FAXFILLFUNC	       1      TIFFFaxFillFunc	 G3/G4 compression pseudo-tag
       TIFFTAG_FAXMODE		       1      int		 - G3/G4 compression pseudo-tag
       TIFFTAG_FILLORDER	       1      uint16		 -
       TIFFTAG_GROUP3OPTIONS	       1      uint32		 -
       TIFFTAG_GROUP4OPTIONS	       1      uint32		 -
       TIFFTAG_HALFTONEHINTS	       2      uint16
       TIFFTAG_HOSTCOMPUTER	       1      char*
       TIFFTAG_ICCPROFILE	       2      uint32,void*	 count, profile data
       TIFFTAG_IMAGEDEPTH	       1      uint32		 -
       TIFFTAG_IMAGEDESCRIPTION        1      char*
       TIFFTAG_IMAGELENGTH	       1      uint32
       TIFFTAG_IMAGEWIDTH	       1      uint32		 -
       TIFFTAG_INKNAMES 	       2      uint16, char*
       TIFFTAG_INKSET		       1      uint16		 -
       TIFFTAG_JPEGCOLORMODE	       1      int		 - JPEG pseudo-tag
       TIFFTAG_JPEGQUALITY	       1      int		 JPEG pseudo-tag
       TIFFTAG_JPEGTABLES	       2      uint32*,void*	 - count & tables
       TIFFTAG_JPEGTABLESMODE	       1      int		 - JPEG pseudo-tag
       TIFFTAG_MAKE		       1      char*
       TIFFTAG_MATTEING 	       1      uint16		 -
       TIFFTAG_MAXSAMPLEVALUE	       1      uint16
       TIFFTAG_MINSAMPLEVALUE	       1      uint16
       TIFFTAG_MODEL		       1      char*
       TIFFTAG_ORIENTATION	       1      uint16
       TIFFTAG_PAGENAME 	       1      char*
       TIFFTAG_PAGENUMBER	       2      uint16
       TIFFTAG_PHOTOMETRIC	       1      uint16
       TIFFTAG_PHOTOSHOP	       ?      uint32,void*	 count, data
       TIFFTAG_PLANARCONFIG	       1      uint16		 -
       TIFFTAG_PREDICTOR	       1      uint16		 -
       TIFFTAG_PRIMARYCHROMATICITIES   1      float*		 6-entry array
       TIFFTAG_REFERENCEBLACKWHITE     1      float*		 - 2*SamplesPerPixel array
       TIFFTAG_RESOLUTIONUNIT	       1      uint16
       TIFFTAG_RICHTIFFIPTC	       2      uint32,void*	 count, data
       TIFFTAG_ROWSPERSTRIP	       1      uint32		 - must be > 0
       TIFFTAG_SAMPLEFORMAT	       1      uint16		 -
       TIFFTAG_SAMPLESPERPIXEL	       1      uint16		 - value must be <= 4
       TIFFTAG_SMAXSAMPLEVALUE	       1      double
       TIFFTAG_SMINSAMPLEVALUE	       1      double
       TIFFTAG_SOFTWARE 	       1      char*
       TIFFTAG_STONITS		       1      double		 -
       TIFFTAG_SUBFILETYPE	       1      uint32
       TIFFTAG_SUBIFD		       2      uint16,uint32*	 count & offsets array
       TIFFTAG_TARGETPRINTER	       1      char*
       TIFFTAG_THRESHHOLDING	       1      uint16
       TIFFTAG_TILEDEPTH	       1      uint32		 -
       TIFFTAG_TILELENGTH	       1      uint32		 - must be a multiple of 8
       TIFFTAG_TILEWIDTH	       1      uint32		 - must be a multiple of 8
       TIFFTAG_TRANSFERFUNCTION        1 or 3= uint16*		 1<<BitsPerSample entry arrays
       TIFFTAG_WHITEPOINT	       1      float*		 2-entry array
       TIFFTAG_XMLPACKET	       2      uint32,void*	 count, data
       TIFFTAG_XPOSITION	       1      float
       TIFFTAG_XRESOLUTION	       1      float
       TIFFTAG_YCBCRCOEFFICIENTS       1      float*		 - 3-entry array
       TIFFTAG_YCBCRPOSITIONING        1      uint16		 -
       TIFFTAG_YCBCRSAMPLING	       2      uint16		 -
       TIFFTAG_YPOSITION	       1      float
       TIFFTAG_YRESOLUTION	       1      float
       - Tag may not have its values changed once data is written.
       = If SamplesPerPixel is one, then a single array is passed; otherwise three arrays should be passed.
       * The contents of this field are quite complex.	See The ICC Profile Format Specification, Annex B.3 "Embedding ICC Profiles in TIFF Files"
       (available at http://www.color.org) for an explanation.

RETURN VALUES

       1 is returned if the operation was successful.  Otherwise, 0 is returned if an error was detected.

DIAGNOSTICS

       All error messages are directed to the TIFFError(3TIFF) routine.

       %s: Cannot modify tag "%s" while writing.  Data has already been written to the file, so the specified tag's  value  can  not  be  changed.
       This restriction is applied to all tags that affect the format of written data.

       %d: Bad value for "%s".	An invalid value was supplied for the named tag.

SEE ALSO

       TIFFOpen(3TIFF), TIFFGetField(3TIFF), TIFFSetDirectory(3TIFF), TIFFWriteDirectory(3TIFF), TIFFReadDirectory(3TIFF), libtiff(3TIFF)

       Libtiff library home page: http://www.remotesensing.org/libtiff/

libtiff 							 October 29, 2004					       TIFFSetField(3TIFF)
All times are GMT -4. The time now is 01:01 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy