Merge `TRANSMUTE()` macro from branch ref: strings/87e102ded928dcc4d9c4c79e22c68b709ea91c40.

Fortune for naka's current commit: Future blessing − 末吉
master
Avril 3 years ago
parent 6bd747a57a
commit f0b9d00705
Signed by: flanchan
GPG Key ID: 284488987C31F630

@ -206,6 +206,14 @@ static_assert_eq(bswap(128lu), 9223372036854775808lu, "bswap128 (lu) failed (1)"
static_assert_eq(128lu, bswap(9223372036854775808lu), "bswap128 (lu) failed (2)");
static_assert_eq(bswap(bswap(128lu)), 128, "bswap128 (lu) failed (3)");
// Transmute
#define TRANSMUTE(val, type) ({ union _trans { var(val) input; type output; }; \
_Static_assert(sizeof(union _trans) == sizeof(type), "Cannot transmute values of different sizes"); \
/* XXX: Do we need do check this for equality? Can we re-word it or do we even need it at all? _Static_assert(_Alignof(union _trans) == _Alignof(type), "Cannot transmute values of different alignments");*/ \
union _trans _trans__value = { .input = (val), }; \
_trans__value.output; })
// Trace message output
#include "trace.h"

@ -0,0 +1,23 @@
#include <string.h>
#include <ints.h>
#include <macros.h>
#include <tests.h>
DEFTEST(transmute_copy)
{
static const u64 EXPECTED = 18446743474098365025lu;
struct { char i[4]; i32 u; } input = { .i = {'a','b','c','d'}, .u = -140 };
let output = TRANSMUTE(input, u64);
TRACE("Transmute test, expected 0x%lx, got 0x%lx", EXPECTED, output);
//XXX: TODO: This test will fail on Big Endian machines.
TEST_ASSERT(output == EXPECTED);
TRACE("Alignment of output: %lu, alignment of input: %lu", _Alignof(output), _Alignof(input));
let input2 = TRANSMUTE(output, var(input));
TRACE("Transmute output passed, trying to transmute back");
TEST_ASSERT( memcmp(&input2, &input, sizeof(input)) == 0 );
return TEST_OK;
}
RUNTEST_DEBUG(transmute_copy);
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