Use faster struct pack/unpack functions for the endian table that matches the host's

diff --git a/Modules/_struct.c b/Modules/_struct.c
index ad54233d48d74b97fc1caa8ce1ac4ca646da0937..06676fa5074cc297a4332f232cc81780dfb254a2 100644 (file)
--- a/Modules/_struct.c
+++ b/Modules/_struct.c
@@ -572,13 +572,13 @@ static formatdef native_table[] = {
        {'I',   sizeof(int),    INT_ALIGN,      nu_uint,        np_uint},
        {'l',   sizeof(long),   LONG_ALIGN,     nu_long,        np_long},
        {'L',   sizeof(long),   LONG_ALIGN,     nu_ulong,       np_ulong},
-       {'f',   sizeof(float),  FLOAT_ALIGN,    nu_float,       np_float},
-       {'d',   sizeof(double), DOUBLE_ALIGN,   nu_double,      np_double},
-       {'P',   sizeof(void *), VOID_P_ALIGN,   nu_void_p,      np_void_p},
 #ifdef HAVE_LONG_LONG
        {'q',   sizeof(PY_LONG_LONG), LONG_LONG_ALIGN, nu_longlong, np_longlong},
        {'Q',   sizeof(PY_LONG_LONG), LONG_LONG_ALIGN, nu_ulonglong,np_ulonglong},
 #endif
+       {'f',   sizeof(float),  FLOAT_ALIGN,    nu_float,       np_float},
+       {'d',   sizeof(double), DOUBLE_ALIGN,   nu_double,      np_double},
+       {'P',   sizeof(void *), VOID_P_ALIGN,   nu_void_p,      np_void_p},
        {0}
 };
 
@@ -1477,6 +1477,30 @@ init_struct(void)
        if (PyType_Ready(&PyStructType) < 0)
                return;
 
+       /* Check endian and swap in faster functions */
+       {
+               int one = 1;
+               formatdef *native = native_table;
+               formatdef *other, *ptr;
+               if ((int)*(unsigned char*)&one)
+                       other = lilendian_table;
+               else
+                       other = bigendian_table;
+               while (native->format != '\0' && other->format != '\0') {
+                       ptr = other;
+                       while (ptr->format != '\0') {
+                               if (ptr->format == native->format) {
+                                       ptr->pack = native->pack;
+                                       ptr->unpack = native->unpack;
+                                       if (ptr == other)
+                                               other++;
+                                       break;
+                               }
+                               ptr++;
+                       }
+                       native++;
+               }
+       }
        
        /* Add some symbolic constants to the module */
        if (StructError == NULL) {