DosFreeThreadLocalMemory: Difference between revisions
Created page with "==Description== Frees a block of thread-local memory that was originally allocated using DosAllocThreadLocalMemory. ==Syntax== <PRE> #define INCL_DOSPROCESS #include <os2.h> ..." |
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#include <os2.h> | #include <os2.h> | ||
ULONG *p; /* | ULONG *p; /* Address of the memory block to free. */ | ||
APIRET rc; /* | APIRET rc; /* Return Code. */ | ||
rc = DosFreeThreadLocalMemory(p); | rc = DosFreeThreadLocalMemory(p); | ||
</PRE> | |||
==Parameters== | ==Parameters== | ||
; | ; p (ULONG *) - input : Address of the memory block to free. | ||
==Return Code== | ==Return Code== | ||
rc (APIRET) - returns | rc (APIRET) - returns | ||
This function returns one of the following values: | This function returns one of the following values: | ||
* 0 NO_ERROR | |||
* 0 | * 87 ERROR_INVALID_PARAMETER | ||
* 87 | |||
==Remarks== | ==Remarks== | ||
| Line 30: | Line 29: | ||
==Example Code== | ==Example Code== | ||
This example shows how to allocate and free 3 DWORDs of local thread memory. | This example shows how to allocate and free 3 DWORDs of local thread memory. | ||
<PRE> | <PRE> | ||
#define INCL_DOSPROCESS | #define INCL_DOSPROCESS | ||
| Line 63: | Line 61: | ||
return NO_ERROR; | return NO_ERROR; | ||
} | } | ||
</PRE> | |||
==Related Functions== | ==Related Functions== | ||
* [[ | *[[DosAllocThreadLocalMemory]] | ||
[[Category: | [[Category:Dos]] | ||
Revision as of 20:38, 26 November 2016
Description
Frees a block of thread-local memory that was originally allocated using DosAllocThreadLocalMemory.
Syntax
#define INCL_DOSPROCESS #include <os2.h> ULONG *p; /* Address of the memory block to free. */ APIRET rc; /* Return Code. */ rc = DosFreeThreadLocalMemory(p);
Parameters
- p (ULONG *) - input
- Address of the memory block to free.
Return Code
rc (APIRET) - returns
This function returns one of the following values:
- 0 NO_ERROR
- 87 ERROR_INVALID_PARAMETER
Remarks
When a process is started, a small block of memory is set aside to be used as a thread-local memory area. This memory is at the same virtual address for each thread, but is backed by different physical memory. This permits each thread to have a small block of memory that is unique, or local, to that thread.
The thread-local memory area consists of 32 DWORDs (128 bytes), each DWORD being 32-bits in size.
Example Code
This example shows how to allocate and free 3 DWORDs of local thread memory.
#define INCL_DOSPROCESS
#define INCL_DOSERRORS
#include <os2.h>
#include <stdio.h> /* Needed for printf */
PULONG pulThreadDWords = NULL; /* Pointer to thread DWORDs returned */
APIRET rc = NO_ERROR; /* Return code */
int main(VOID) {
/* Allocate 3 DWORDs of local thread memory */
rc = DosAllocThreadLocalMemory(3, /* Number of DWORDs */
&pulThreadDWords); /* Address returned */
if (rc != NO_ERROR) {
printf("DosAllocThreadLocalMemory error: return code = %u\n", rc);
return 1;
}
/* ... Use the thread-local memory ... */
rc = DosFreeThreadLocalMemory(pulThreadDWords); /* Free the DWORDs */
if (rc != NO_ERROR) {
printf("DosFreeThreadLocalMemory error: return code = %u\n", rc);
return 1;
}
return NO_ERROR;
}