1 /* _PDCLIB_allocpages( int const )
3 This file is part of the Public Domain C Library (PDCLib).
4 Permission is granted to use, modify, and / or redistribute at will.
7 /* This is an example implementation of _PDCLIB_allocpages() (declared in
8 _PDCLIB_config.h), fit for use with POSIX kernels.
17 void * sbrk( intptr_t );
19 #include "_PDCLIB_glue.h"
21 static void * membreak = NULL;
23 void * _PDCLIB_allocpages( int const n )
25 if ( membreak == NULL )
27 /* first call, make sure end-of-heap is page-aligned */
28 intptr_t unaligned = 0;
30 unaligned = _PDCLIB_PAGESIZE - (intptr_t)membreak % _PDCLIB_PAGESIZE;
31 if ( unaligned < _PDCLIB_PAGESIZE )
33 /* end-of-heap not page-aligned - adjust */
34 if ( sbrk( unaligned ) != membreak )
39 membreak = (char *)membreak + unaligned;
42 /* increasing or decreasing heap - standard operation */
43 void * oldbreak = membreak;
44 membreak = (void *)( (char *)membreak + ( n * _PDCLIB_PAGESIZE ) );
46 if ( sbrk( (char*)membreak - (char*)oldbreak ) == membreak )
48 if ( brk( membreak ) == 0 )
66 #include "_PDCLIB_test.h"
71 char * startbreak = sbrk( 0 );
72 TESTCASE( _PDCLIB_allocpages( 0 ) );
73 TESTCASE( ( (char *)sbrk( 0 ) - startbreak ) <= _PDCLIB_PAGESIZE );
74 startbreak = sbrk( 0 );
75 TESTCASE( _PDCLIB_allocpages( 1 ) );
76 TESTCASE( sbrk( 0 ) == startbreak + ( 1 * _PDCLIB_PAGESIZE ) );
77 TESTCASE( _PDCLIB_allocpages( 5 ) );
78 TESTCASE( sbrk( 0 ) == startbreak + ( 6 * _PDCLIB_PAGESIZE ) );
79 TESTCASE( _PDCLIB_allocpages( -3 ) );
80 TESTCASE( sbrk( 0 ) == startbreak + ( 3 * _PDCLIB_PAGESIZE ) );