[FFmpeg-devel] [RFC] remove lrintf fallback implementation

[Víctor Paesa]

Hi,

M?ns Rullg?rd said:
> "V?ctor Paesa" <wzrlpy at arsystel.com> writes:
>
>> Index: configure
>> ==================================================================>
>> --- configure   (revision 10822) +++ configure   (working copy)
>> @@ -701,6 +701,7 @@
>>      getrusage
>>      imlib2
>>      inet_aton
>> +    llrint
>>      lrintf
>>      machine_ioctl_bt848_h
>>      machine_ioctl_meteor_h
>
> Alphabetical order OK.

Remarkably unusual, isn't it? ;-)

>> @@ -1501,6 +1502,7 @@
>>  check_func inet_aton
>>  check_func memalign
>>  check_func mkstemp
>> +check_func2 math.h llrint
>>  check_func2 windows.h GetProcessTimes
>
> Is it necessary to use check_func2?

check_func works also fine for Cygwin, though I can't speak for other
systems.

>> Index: libavutil/internal.h
>> ==================================================================>
>> --- libavutil/internal.h        (revision 10822) +++
>> libavutil/internal.h        (working copy)
>> @@ -278,4 +278,17 @@
>>  }
>>  #endif /* HAVE_LRINTF */
>>
>> +#ifndef HAVE_LLRINT
>> +#if defined(ARCH_X86)
>> +static av_always_inline long long int llrint(double x)
>> +{
>> +    long long int llrintres;
>> +    asm
>> +    ("fistpll %0"
>> +    : "=m" (llrintres) : "t" (x) : "st");
>
> The formatting of this asm() statement is incredibly ugly.

I must confess I am an asm-illiterate, for me every asm is ugly. I made
another (mostly blind) attempt.

>> +    return llrintres;
>> +}
>> +#endif /* defined(ARCH_X86) */
>> +#endif /* HAVE_LLRINT */
>
> And what it's not ARCH_X86?

I cannot remember any other architecture reporting here the lack of
llrint(), should they exist, they can also add some asm().

Regards,
V?ctor

Patch follows:

$ svn diff configure libavutil/internal.h
Index: configure
===================================================================
--- configure   (revision 10822)
+++ configure   (working copy)
@@ -701,6 +701,7 @@
     getrusage
     imlib2
     inet_aton
+    llrint
     lrintf
     machine_ioctl_bt848_h
     machine_ioctl_meteor_h
@@ -1499,6 +1500,7 @@
 check_func gethrtime
 check_func getrusage
 check_func inet_aton
+check_func llrint
 check_func memalign
 check_func mkstemp
 check_func2 windows.h GetProcessTimes
Index: libavutil/internal.h
===================================================================
--- libavutil/internal.h        (revision 10822)
+++ libavutil/internal.h        (working copy)
@@ -278,4 +278,17 @@
 }
 #endif /* HAVE_LRINTF */

+#ifndef HAVE_LLRINT
+#if defined(ARCH_X86)
+static av_always_inline long long int llrint(double x)
+{
+    long long int llrintres;
+    asm(
+        "fistpll %0" : "=m" (llrintres) : "t" (x) : "st"
+    );
+    return llrintres;
+}
+#endif /* defined(ARCH_X86) */
+#endif /* HAVE_LLRINT */
+
 #endif /* FFMPEG_INTERNAL_H */