fgets problems Post: 302396959

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Top Forums Programming fgets problems Post 302396959 by CRGreathouse on Saturday 20th of February 2010 01:24:28 AM

02-20-2010

Registered User

Quote:

Originally Posted by jim mcnamara

You have a lot of heap memory involvement. ie., hidden library calls to malloc - you need a malloc debugger.

Huge amounts of memory management -- much more in the calculation parts of my program. Pari essentially forces you to manage all your own memory.

But malloc itself isn't really ever called, not even in the library calls (except initialization). All the memory is allocated initially, and the program tracks usage itself. So when I write

Code:

GEN x = stoi(3); // x = 3
GEN y = stoi(4); // y = 4
GEN z = addii(x, y); // z = x + y
z = mulii(z, x); // z *= x

malloc is called zero times in that sequence, but four objects are created in a large block of memory. The block of memory (called the Pari stack -- but it's just a large malloc'd variable, really) functions as a stack, insofar as it's my responsibility to leave return values at the top and move the pointers as needed to let garbage drop off.

Do you think these programs would be able to handle such a low-level system?

CRGreathouse

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LEARN ABOUT LINUX

malloc_trim

MALLOC_TRIM(3)						     Linux Programmer's Manual						    MALLOC_TRIM(3)

NAME

       malloc_trim - release free memory from the top of the heap

SYNOPSIS

       #include <malloc.h>

       int malloc_trim(size_t pad);

DESCRIPTION

       The malloc_trim() function attempts to release free memory at the top of the heap (by calling sbrk(2) with a suitable argument).

       The  pad  argument  specifies  the amount of free space to leave untrimmed at the top of the heap.  If this argument is 0, only the minimum
       amount of memory is maintained at the top of the heap (i.e., one page or less).	A nonzero argument can be used to maintain  some  trailing
       space at the top of the heap in order to allow future allocations to be made without having to extend the heap with sbrk(2).

RETURN VALUE

       The malloc_trim() function returns 1 if memory was actually released back to the system, or 0 if it was not possible to release any memory.

ERRORS

       No errors are defined.

CONFORMING TO

       This function is a GNU extension.

NOTES

       This  function  is  automatically  called by free(3) in certain circumstances; see the discussion of M_TOP_PAD and M_TRIM_THRESHOLD in mal-
       lopt(3).

       This function cannot release free memory located at places other than the top of the heap.

       This function releases only memory in the main arena.

SEE ALSO

       sbrk(2), malloc(3), mallopt(3)

Linux								    2014-05-28							    MALLOC_TRIM(3)

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