X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=platform%2Fposix%2Ffunctions%2F_PDCLIB%2Fallocpages.c;fp=platform%2Fposix%2Ffunctions%2F_PDCLIB%2Fallocpages.c;h=435e8c64b8840fa7c429f2faadaf9d81caca3d8a;hb=a38d56a6a13dbb89022b5448d2d5247f3f99ea41;hp=0000000000000000000000000000000000000000;hpb=81f4c957d2f820d9340d90d5b650cbbed054caa0;p=pdclib.old

diff --git a/platform/posix/functions/_PDCLIB/allocpages.c b/platform/posix/functions/_PDCLIB/allocpages.c
new file mode 100644
index 0000000..435e8c6
--- /dev/null
+++ b/platform/posix/functions/_PDCLIB/allocpages.c
@@ -0,0 +1,83 @@
+/* $Id$ */
+
+/* _PDCLIB_allocpages( int const )
+
+   This file is part of the Public Domain C Library (PDCLib).
+   Permission is granted to use, modify, and / or redistribute at will.
+*/
+
+/* This is an example implementation of _PDCLIB_allocpages() (declared in
+   _PDCLIB_config.h), fit for use with POSIX kernels.
+*/
+
+#include <stdint.h>
+#include <stddef.h>
+
+int brk( void * );
+void * sbrk( intptr_t );
+
+#ifndef _PDCLIB_GLUE_H
+#define _PDCLIB_GLUE_H _PDCLIB_GLUE_H
+#include <_PDCLIB_glue.h>
+#endif
+
+static void * membreak = NULL;
+
+void * _PDCLIB_allocpages( int const n )
+{
+    if ( membreak == NULL )
+    {
+        /* first call, make sure end-of-heap is page-aligned */
+        intptr_t unaligned = 0;
+        membreak = sbrk( 0 );
+        unaligned = _PDCLIB_PAGESIZE - (intptr_t)membreak % _PDCLIB_PAGESIZE;
+        if ( unaligned < _PDCLIB_PAGESIZE )
+        {
+            /* end-of-heap not page-aligned - adjust */
+            if ( sbrk( unaligned ) != membreak )
+            {
+                /* error */
+                return NULL;
+            }
+            membreak = (char *)membreak + unaligned;
+        }
+    }
+    /* increasing or decreasing heap - standard operation */
+    void * oldbreak = membreak;
+    membreak = (void *)( (char *)membreak + ( n * _PDCLIB_PAGESIZE ) );
+    if ( brk( membreak ) == 0 )
+    {
+        /* successful */
+        return oldbreak;
+    }
+    else
+    {
+        /* out of memory */
+        membreak = oldbreak;
+        return NULL;
+    }
+}
+
+#ifdef TEST
+#include <_PDCLIB_test.h>
+
+int main( void )
+{
+#ifndef REGTEST
+    {
+    char * startbreak = sbrk( 0 );
+    TESTCASE( _PDCLIB_allocpages( 0 ) );
+    TESTCASE( ( (char *)sbrk( 0 ) - startbreak ) <= _PDCLIB_PAGESIZE );
+    startbreak = sbrk( 0 );
+    TESTCASE( _PDCLIB_allocpages( 1 ) );
+    TESTCASE( sbrk( 0 ) == startbreak + ( 1 * _PDCLIB_PAGESIZE ) );
+    TESTCASE( _PDCLIB_allocpages( 5 ) );
+    TESTCASE( sbrk( 0 ) == startbreak + ( 6 * _PDCLIB_PAGESIZE ) );
+    TESTCASE( _PDCLIB_allocpages( -3 ) );
+    TESTCASE( sbrk( 0 ) == startbreak + ( 3 * _PDCLIB_PAGESIZE ) );
+    }
+#endif
+    return TEST_RESULTS;
+}
+
+#endif