_BitScanForward() and friends are part of the Windows API and
take DWORD as parameter type. DWORD is defined to be 'unsigned long'
in Windows' header files.
We call into these functions from within lib/util.h. Currently, we
pass arguments of type uint32_t which is type defined to
'unsigned int'. This incompatiblity causes failures when we compile
the code as C++ code or with warnings enabled.
The fix is to use 'unsigned long' rather than fixed size type.
A simplied version of the problem is illustrated using a sample
program:
-------
$ cat test.c
void
init_dword(DWORD *d)
{
*d = 0;
}
int main()
{
uint32_t u;
init_dword(&u);
return 0;
}
===========
Problem manifests when warnings are enabled, and compiled as 'C' code:
===========
$ cl -WX -W4 test.c
Microsoft (R) C/C++ Optimizing Compiler Version 18.00.21005.1 for x86
Copyright (C) Microsoft Corporation. All rights reserved.
test.c
test.c(14) : error C2220: warning treated as error - no 'object' file generated
test.c(14) : warning C4057: 'function' : 'DWORD *' differs in indirection to
slightly different base types from 'uint32_t *'
===========
Problem manifests when code is compiled as 'C++' code:
===========
$ cl -Tptest.c
Microsoft (R) C/C++ Optimizing Compiler Version 18.00.21005.1 for x86
Copyright (C) Microsoft Corporation. All rights reserved.
test.c
test.c(14) : error C2664: 'void init_dword(DWORD *)' : cannot convert argument
1 from 'uint32_t *' to 'DWORD *'
Types pointed to are unrelated; conversion requires reinterpret_cast,
C-style cast or function-style cast
-------
Signed-off-by: Nithin Raju <nit...@vmware.com>
Co-Authored-by: Linda Sun <l...@vmware.com>
---
lib/util.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/lib/util.h b/lib/util.h
index cbaa3ac..276edb5 100644
--- a/lib/util.h
+++ b/lib/util.h
@@ -352,11 +352,11 @@ static inline int
raw_ctz(uint64_t n)
{
#ifdef _WIN64
- uint32_t r = 0;
+ unsigned long r = 0;
_BitScanForward64(&r, n);
return r;
#else
- uint32_t low = n, high, r = 0;
+ unsigned long low = n, high, r = 0;
if (_BitScanForward(&r, low)) {
return r;
}
@@ -370,11 +370,11 @@ static inline int
raw_clz64(uint64_t n)
{
#ifdef _WIN64
- uint32_t r = 0;
+ unsigned long r = 0;
_BitScanReverse64(&r, n);
return 63 - r;
#else
- uint32_t low, high = n >> 32, r = 0;
+ unsigned long low, high = n >> 32, r = 0;
if (_BitScanReverse(&r, high)) {
return 31 - r;
}
--
1.9.4.msysgit.2
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