Re: [Mingw-w64-public] [PATCH] headers: Implement the _bittest* intrinsics for arm and aarch64

[Martin Storsjö]

On Wed, 14 Jul 2021, LIU Hao wrote:


在 7/14/21 9:02 PM, Martin Storsjö 写道:

+unsigned char _bittestandset(__LONG32 *__a, __LONG32 __b)
+{
+unsigned char __v = (*__a >> __b) & 1;
+*__a |= (1 << __b);


I suggest `1UL` here, as shifting 1 to the left by 31 is undefined behavior.


Thanks, will update all these.

// Martin

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Re: [Mingw-w64-public] [PATCH] headers: Implement the _bittest* intrinsics for arm and aarch64

[LIU Hao]

在 7/14/21 9:02 PM, Martin Storsjö 写道:

+unsigned char _bittestandset(__LONG32 *__a, __LONG32 __b)
+{
+unsigned char __v = (*__a >> __b) & 1;
+*__a |= (1 << __b);


I suggest `1UL` here, as shifting 1 to the left by 31 is undefined behavior.



+unsigned char _bittestandreset(__LONG32 *__a, __LONG32 __b)
+{
+unsigned char __v = (*__a >> __b) & 1;
+*__a &= ~(1 << __b);


Likewise.



+unsigned char _bittestandcomplement(__LONG32 *__a, __LONG32 __b)
+{
+unsigned char __v = (*__a >> __b) & 1;
+*__a = (*__a & ~(1 << __b)) | ((__v ^ 1) << __b);


Likewise.



+unsigned char _bittestandset64(__int64 *__a, __int64 __b)
+{
+unsigned char __v = (*__a >> __b) & 1;
+*__a |= (1LL << __b);


Likewise, but `1ULL`, and more follow.


--
Best regards,
LIU Hao



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