musl - Re: Considering x86-64 fenv.s to C

Follow @Openwall on Twitter for new release announcements and other news

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.LRH.2.02.2001261416150.4450@key0.esi.com.au>
Date: Sun, 26 Jan 2020 14:28:37 +1100 (AEDT)
From: Damian McGuckin <damianm@....com.au>
To: musl@...ts.openwall.com
Subject: Re: Considering x86-64 fenv.s to C


M68K is below:

I looked inside 'fenv.c' inside the .../fenv/arm directory and noticed
it pulled in a default trivial 'fenv.c' from the directory above it.

In the absence of an alternative, I might exploit that but say

 	#include	"../fenv-trivial.c"

for that trivial case and

 	#include	"../fenv-generic.c"

for the new generic architecture.

Apologizing in advance for insuficient comments, but the hardware specific 
fenv.c for (say) the m68k is

/*
  * 68k ARCHITECTURE
  *
  * this CPU has distinct control and status registers
  */
#include	<fenv.h>

#if __HAVE_68881 || __mcffpu__

static inline unsigned int fe_get_sr_arch()
{
 	unsigned int v;

 	__asm__ __volatile__ ("fmove.l %%fpsr,%0" : "=dm"(v));
 	return v;
}

static inline void fe_set_sr_arch(unsigned v)
{
 	__asm__ __volatile__ ("fmove.l %0,%%fpsr" : : "dm"(v));
}

static inline unsigned int fe_get_cr_arch()
{
 	unsigned int v;

 	__asm__ __volatile__ ("fmove.l %%fpcr,%0" : "=dm"(v));
 	return v;
}

static inline void fe_set_cr_arch(unsigned v)
{
 	__asm__ __volatile__ ("fmove.l %0,%%fpcr" : : "dm"(v));
}

static inline unsigned int fe_get_ia_arch()
{
 	unsigned int address;

 	__asm__ __volatile__ ("fmove.l %%fpiar,%0" : "=dm"(address));
 	return address;
}

static inline void fe_set_ia_arch(unsigned int address)
{
 	__asm__ __volatile__ ("fmove.l %0,%%fpiar" : : "dm"(address));
}

/*
  * Expose the above generically
  */
#define	fe_get_sr	fe_get_sr_arch
#define	fe_set_sr	fe_set_sr_arch
#define	fe_get_cr	fe_get_cr_arch
#define	fe_set_cr	fe_set_cr_arch

/*
  * Handle the environment (which is a struct)
  */
#define	fe_get_e(e)\
 		((e)->__control_register = fe_get_cr_arch(),\
 		(e)->__status_register = fe_get_sr_arch(),\
 		(e)->__archnstruction_address = fe_get_ia_arch())
#define	fe_set_e(e)\
 		(fe_set_cr_arch((e)->__control_register),\
 		fe_set_sr_arch((e)->__status_register),\
 		fe_set_ia_arch((e)->__instruction_address))

/* the contents of the default fenv_t  */

#define	FE_DFL_ENV_DATA	{ 0, 0, 0 }

#include	"../fenv-generic.c"

#else

#include	"../fenv-trivial.c"

#endif


Regards - Damian

Pacific Engineering Systems International, 277-279 Broadway, Glebe NSW 2037
Ph:+61-2-8571-0847 .. Fx:+61-2-9692-9623 | unsolicited email not wanted here
Views & opinions here are mine and not those of any past or present employer

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.