1 files changed, 90 insertions, 0 deletions
diff --git a/src/pdclib/functions/_PDCLIB/_PDCLIB_filemode.c b/src/pdclib/functions/_PDCLIB/_PDCLIB_filemode.c
new file mode 100644
index 0000000..2555a00
--- /dev/null
+++ b/src/pdclib/functions/_PDCLIB/_PDCLIB_filemode.c
@@ -0,0 +1,90 @@
+/* _PDCLIB_filemode( const char * )
+
+   This file is part of the Public Domain C Library (PDCLib).
+   Permission is granted to use, modify, and / or redistribute at will.
+*/
+
+#include <stddef.h>
+
+#ifndef REGTEST
+
+/* Helper function that parses the C-style mode string passed to fopen() into
+   the PDCLib flags FREAD, FWRITE, FAPPEND, FRW (read-write) and FBIN (binary
+   mode).
+*/
+unsigned int _PDCLIB_filemode( const char * const mode )
+{
+    unsigned rc = 0;
+    size_t i;
+    switch ( mode[0] )
+    {
+        case 'r':
+            rc |= _PDCLIB_FREAD;
+            break;
+        case 'w':
+            rc |= _PDCLIB_FWRITE;
+            break;
+        case 'a':
+            rc |= _PDCLIB_FAPPEND | _PDCLIB_FWRITE;
+            break;
+        default:
+            /* Other than read, write, or append - invalid */
+            return 0;
+    }
+    for ( i = 1; i < 4; ++i )
+    {
+        switch ( mode[i] )
+        {
+            case '+':
+                if ( rc & _PDCLIB_FRW ) return 0; /* Duplicates are invalid */
+                rc |= _PDCLIB_FRW;
+                break;
+            case 'b':
+                if ( rc & _PDCLIB_FBIN ) return 0; /* Duplicates are invalid */
+                rc |= _PDCLIB_FBIN;
+                break;
+            case '\0':
+                /* End of mode */
+                return rc;
+            default:
+                /* Other than read/write or binary - invalid. */
+                return 0;
+        }
+    }
+    /* Longer than three chars - invalid. */
+    return 0;
+}
+
+#endif
+
+#ifdef TEST
+
+#include "_PDCLIB_test.h"
+
+int main( void )
+{
+#ifndef REGTEST
+    TESTCASE( _PDCLIB_filemode( "r" ) == _PDCLIB_FREAD );
+    TESTCASE( _PDCLIB_filemode( "w" ) == _PDCLIB_FWRITE );
+    TESTCASE( _PDCLIB_filemode( "a" ) == ( _PDCLIB_FAPPEND | _PDCLIB_FWRITE ) );
+    TESTCASE( _PDCLIB_filemode( "r+" ) == ( _PDCLIB_FREAD | _PDCLIB_FRW ) );
+    TESTCASE( _PDCLIB_filemode( "w+" ) == ( _PDCLIB_FWRITE | _PDCLIB_FRW ) );
+    TESTCASE( _PDCLIB_filemode( "a+" ) == ( _PDCLIB_FAPPEND | _PDCLIB_FWRITE | _PDCLIB_FRW ) );
+    TESTCASE( _PDCLIB_filemode( "rb" ) == ( _PDCLIB_FREAD | _PDCLIB_FBIN ) );
+    TESTCASE( _PDCLIB_filemode( "wb" ) == ( _PDCLIB_FWRITE | _PDCLIB_FBIN ) );
+    TESTCASE( _PDCLIB_filemode( "ab" ) == ( _PDCLIB_FAPPEND | _PDCLIB_FWRITE | _PDCLIB_FBIN ) );
+    TESTCASE( _PDCLIB_filemode( "r+b" ) == ( _PDCLIB_FREAD | _PDCLIB_FRW | _PDCLIB_FBIN ) );
+    TESTCASE( _PDCLIB_filemode( "w+b" ) == ( _PDCLIB_FWRITE | _PDCLIB_FRW | _PDCLIB_FBIN ) );
+    TESTCASE( _PDCLIB_filemode( "a+b" ) == ( _PDCLIB_FAPPEND | _PDCLIB_FWRITE | _PDCLIB_FRW | _PDCLIB_FBIN ) );
+    TESTCASE( _PDCLIB_filemode( "rb+" ) == ( _PDCLIB_FREAD | _PDCLIB_FRW | _PDCLIB_FBIN ) );
+    TESTCASE( _PDCLIB_filemode( "wb+" ) == ( _PDCLIB_FWRITE | _PDCLIB_FRW | _PDCLIB_FBIN ) );
+    TESTCASE( _PDCLIB_filemode( "ab+" ) == ( _PDCLIB_FAPPEND | _PDCLIB_FWRITE | _PDCLIB_FRW | _PDCLIB_FBIN ) );
+    TESTCASE( _PDCLIB_filemode( "x" ) == 0 );
+    TESTCASE( _PDCLIB_filemode( "r++" ) == 0 );
+    TESTCASE( _PDCLIB_filemode( "wbb" ) == 0 );
+    TESTCASE( _PDCLIB_filemode( "a+bx" ) == 0 );
+#endif
+    return TEST_RESULTS;
+}
+
+#endif