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/*
* Copyright (c) 2012 The Native Client Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include <assert.h>
#include <sched.h>
#include <stdint.h>
#include <stdio.h>
#if defined(__i386__) || defined(__x86_64__)
typedef uint16_t fpcw_t;
#define X86_FPCW_PREC_MASK 0x300
#define X86_FPCW_PREC_DOUBLE 0x200
#define X86_FPCW_PREC_EXTENDED 0x300
static uint16_t get_fpcw(void) {
uint16_t fpcw;
__asm__ __volatile__("fnstcw %0": "=m" (fpcw));
return fpcw;
}
static void set_fpcw(uint16_t fpcw) {
__asm__ __volatile__("fldcw %0": : "m" (fpcw));
}
static fpcw_t modify_fpcw_bits(fpcw_t orig_fpcw) {
assert(orig_fpcw & X86_FPCW_PREC_EXTENDED);
return (orig_fpcw & ~X86_FPCW_PREC_MASK) | X86_FPCW_PREC_DOUBLE;
}
typedef uint32_t mxcsr_t;
#define X86_MXCSR_FLUSH_ZERO 0x8000
static mxcsr_t get_mxcsr(void) {
uint32_t mxcsr;
__asm__ __volatile__("stmxcsr %0" : "=m" (mxcsr));
return mxcsr;
}
static void set_mxcsr(mxcsr_t mxcsr) {
__asm__ __volatile__("ldmxcsr %0" :: "m" (mxcsr));
}
static mxcsr_t modify_mxcsr_bits(mxcsr_t orig_mxcsr) {
assert((orig_mxcsr & X86_MXCSR_FLUSH_ZERO) == 0);
return orig_mxcsr | X86_MXCSR_FLUSH_ZERO;
}
#elif defined(__arm__)
typedef uint32_t fpcw_t;
#define ARM_FPSCR_ROUND_MASK 0xc00000
#define ARM_FPSCR_ROUND_TONEAREST 0x000000
#define ARM_FPSCR_ROUND_UPWARD 0x800000
#define ARM_FPSCR_ROUND_DOWNWARD 0x400000
#define ARM_FPSCR_ROUND_TOWARDZERO 0xc00000
/*
* These are defined in test_fpu_control_word_arm.S because
* PNaCl/LLVM cannot handle the inline assembly for these instructions.
*/
fpcw_t get_fpcw(void);
void set_fpcw(fpcw_t);
static fpcw_t modify_fpcw_bits(fpcw_t orig_fpcw) {
assert((orig_fpcw & ARM_FPSCR_ROUND_MASK) == ARM_FPSCR_ROUND_TONEAREST);
return (orig_fpcw & ~ARM_FPSCR_ROUND_MASK) | ARM_FPSCR_ROUND_TOWARDZERO;
}
typedef int mxcsr_t;
static mxcsr_t get_mxcsr(void) {
return 0;
}
static void set_mxcsr(mxcsr_t mxcsr __attribute__((unused))) {
}
static mxcsr_t modify_mxcsr_bits(mxcsr_t orig_mxcsr) {
return orig_mxcsr;
}
#else
#error unsupported architecture
#endif
int main(void) {
int result = 0;
fpcw_t fpcw1;
fpcw_t fpcw2;
mxcsr_t mxcsr1;
mxcsr_t mxcsr2;
/*
* Change the FPU control word to a non-default setting.
*/
fpcw1 = get_fpcw();
fpcw1 = modify_fpcw_bits(fpcw1);
set_fpcw(fpcw1);
mxcsr1 = get_mxcsr();
mxcsr1 = modify_mxcsr_bits(mxcsr1);
set_mxcsr(mxcsr1);
/*
* Now do a system call. It's supposed to clear the rest of the FPU
* state, but leave the control word intact.
*/
sched_yield();
/*
* Now check what we got.
*/
fpcw2 = get_fpcw();
if (fpcw2 != fpcw1) {
fprintf(stderr, "Set FPCW to %#x and got back %#x\n",
(unsigned int) fpcw1, (unsigned int) fpcw2);
result = 1;
}
mxcsr2 = get_mxcsr();
if (mxcsr2 != mxcsr1) {
fprintf(stderr, "Set MXCSR to %#x and got back %#x\n",
(unsigned int) mxcsr1, (unsigned int) mxcsr2);
result = 1;
}
return result;
}
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