lib/libm: Allow math funcs to be used by non-Thumb archs.

Requires addition of software implementation of sqrtf function.
crypto-aes
Damien George 7 years ago
parent 0e1b5faad5
commit a67651406d
  1. 102
      lib/libm/ef_sqrt.c
  2. 9
      lib/libm/math.c

@ -0,0 +1,102 @@
/*
* This file is part of the MicroPython project, http://micropython.org/
*
* These math functions are taken from newlib-nano-2, the newlib/libm/math
* directory, available from https://github.com/32bitmicro/newlib-nano-2.
*
* Appropriate copyright headers are reproduced below.
*/
/* ef_sqrtf.c -- float version of e_sqrt.c.
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
*/
/*
* ====================================================
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
*
* Developed at SunPro, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/
#include "fdlibm.h"
#ifdef __STDC__
static const float one = 1.0, tiny=1.0e-30;
#else
static float one = 1.0, tiny=1.0e-30;
#endif
// sqrtf is exactly __ieee754_sqrtf when _IEEE_LIBM defined
float sqrtf(float x)
/*
#ifdef __STDC__
float __ieee754_sqrtf(float x)
#else
float __ieee754_sqrtf(x)
float x;
#endif
*/
{
float z;
__uint32_t r,hx;
__int32_t ix,s,q,m,t,i;
GET_FLOAT_WORD(ix,x);
hx = ix&0x7fffffff;
/* take care of Inf and NaN */
if(!FLT_UWORD_IS_FINITE(hx))
return x*x+x; /* sqrt(NaN)=NaN, sqrt(+inf)=+inf
sqrt(-inf)=sNaN */
/* take care of zero and -ves */
if(FLT_UWORD_IS_ZERO(hx)) return x;/* sqrt(+-0) = +-0 */
if(ix<0) return (x-x)/(x-x); /* sqrt(-ve) = sNaN */
/* normalize x */
m = (ix>>23);
if(FLT_UWORD_IS_SUBNORMAL(hx)) { /* subnormal x */
for(i=0;(ix&0x00800000L)==0;i++) ix<<=1;
m -= i-1;
}
m -= 127; /* unbias exponent */
ix = (ix&0x007fffffL)|0x00800000L;
if(m&1) /* odd m, double x to make it even */
ix += ix;
m >>= 1; /* m = [m/2] */
/* generate sqrt(x) bit by bit */
ix += ix;
q = s = 0; /* q = sqrt(x) */
r = 0x01000000L; /* r = moving bit from right to left */
while(r!=0) {
t = s+r;
if(t<=ix) {
s = t+r;
ix -= t;
q += r;
}
ix += ix;
r>>=1;
}
/* use floating add to find out rounding direction */
if(ix!=0) {
z = one-tiny; /* trigger inexact flag */
if (z>=one) {
z = one+tiny;
if (z>one)
q += 2;
else
q += (q&1);
}
}
ix = (q>>1)+0x3f000000L;
ix += (m <<23);
SET_FLOAT_WORD(z,ix);
return z;
}

@ -45,6 +45,8 @@ typedef union {
};
} double_s_t;
#if defined(__thumb__)
double __attribute__((pcs("aapcs"))) __aeabi_i2d(int32_t x) {
return (float)x;
}
@ -82,6 +84,11 @@ double __aeabi_dmul(double x , double y) {
}
#endif // defined(__thumb__)
// TODO this needs a better way of testing for Thumb2 FP hardware
#if defined(__thumb2__)
float sqrtf(float x) {
asm volatile (
"vsqrt.f32 %[r], %[x]\n"
@ -90,6 +97,8 @@ float sqrtf(float x) {
return x;
}
#endif
#ifndef NDEBUG
float copysignf(float x, float y) {
float_s_t fx={.f = x};

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