Merge pull request #29 from ReadAlongs/test_byteorder

Correct pointer aliasing in SWAP_FLOAT32

include/soundswallower/byteorder.h

@@ -71,7 +71,10 @@
 				(0xff000000 & (*(x))<<24))
 
 /* Macro to byteswap a float32 variable.  x = ptr to variable */
-#define SWAP_FLOAT32(x)	SWAP_INT32((int32 *) x)
+#define SWAP_FLOAT32(x)	{ uint8 tmp, *ux = (uint8 *)x;    \
+    tmp = ux[3]; ux[3] = ux[0]; ux[0] = tmp; \
+    tmp = ux[2]; ux[2] = ux[1]; ux[1] = tmp; \
+}
 
 /* Macro to byteswap a float64 variable.  x = ptr to variable */
 #define SWAP_FLOAT64(x)	{ int32 *low = (int32 *) (x), *high = (int32 *) (x) + 1,\

tests/CMakeLists.txt

@@ -7,6 +7,7 @@ set(TESTS
   test_acmod_grow
   test_add_words
   test_bitvec
+  test_byteorder
   test_ckd_alloc
   test_ckd_alloc_catch
   test_dict2pid

tests/test_byteorder.c

@@ -0,0 +1,57 @@
+#include "config.h"
+
+#include <stdio.h>
+#include <time.h>
+
+#include <soundswallower/byteorder.h>
+#include <soundswallower/profile.h>
+
+#include "test_macros.h"
+
+int
+main(int argc, char *argv[])
+{
+    uint32 ui32 = 0xdeadbeef;
+    int32 i32 = 0x12345678;
+    uint16 ui16 = 0xfeed;
+    int16 i16 = 0x1234;
+    float32 f32a = 382.23328f;
+    float32 f32b = -0.1246f;
+    ptmr_t t;
+    int i;
+
+    (void)argc; (void)argv;
+    SWAP_INT32(&ui32);
+    TEST_EQUAL(0xefbeadde, ui32);
+    SWAP_INT32(&i32);
+    TEST_EQUAL(0x78563412, i32);
+
+    SWAP_INT16(&ui16);
+    TEST_EQUAL(0xedfe, ui16);
+    SWAP_INT16(&i16);
+    TEST_EQUAL(0x3412, i16);
+
+    SWAP_FLOAT32(&f32a);
+    TEST_ASSERT(fabs(f32a - -1.77607e+17f) < 1e16f);
+    SWAP_FLOAT32(&f32a);
+    TEST_EQUAL_FLOAT(f32a, 382.23328f);
+    SWAP_FLOAT32(&f32b);
+    TEST_ASSERT(fabs(f32b - 716796.0f) < 1.0f);
+    SWAP_FLOAT32(&f32b);
+    TEST_EQUAL_FLOAT(f32b, -0.1246f);
+
+    ptmr_start(&t);
+    for (i = 0; i < 10000000; ++i) {
+        SWAP_FLOAT32(&f32a);
+    }
+    ptmr_stop(&t);
+    printf("10M SWAP_FLOAT32 in %g\n", t.t_cpu);
+    ptmr_reset(&t);
+    ptmr_start(&t);
+    for (i = 0; i < 10000000; ++i) {
+        SWAP_INT32(&ui32);
+    }
+    ptmr_stop(&t);
+    printf("10M SWAP_INT32 in %g\n", t.t_cpu);
+    return 0;
+}