Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0-only
/* IEEE754 floating point arithmetic
 * single precision square root
 */
/*
 * MIPS floating point support
 * Copyright (C) 1994-2000 Algorithmics Ltd.
 */
 
#include "ieee754sp.h"
 
union ieee754sp ieee754sp_sqrt(union ieee754sp x)
{
<------>int ix, s, q, m, t, i;
<------>unsigned int r;
<------>COMPXSP;
 
<------>/* take care of Inf and NaN */
 
<------>EXPLODEXSP;
<------>ieee754_clearcx();
<------>FLUSHXSP;
 
<------>/* x == INF or NAN? */
<------>switch (xc) {
<------>case IEEE754_CLASS_SNAN:
<------><------>return ieee754sp_nanxcpt(x);
 
<------>case IEEE754_CLASS_QNAN:
<------><------>/* sqrt(Nan) = Nan */
<------><------>return x;
 
<------>case IEEE754_CLASS_ZERO:
<------><------>/* sqrt(0) = 0 */
<------><------>return x;
 
<------>case IEEE754_CLASS_INF:
<------><------>if (xs) {
<------><------><------>/* sqrt(-Inf) = Nan */
<------><------><------>ieee754_setcx(IEEE754_INVALID_OPERATION);
<------><------><------>return ieee754sp_indef();
<------><------>}
<------><------>/* sqrt(+Inf) = Inf */
<------><------>return x;
 
<------>case IEEE754_CLASS_DNORM:
<------>case IEEE754_CLASS_NORM:
<------><------>if (xs) {
<------><------><------>/* sqrt(-x) = Nan */
<------><------><------>ieee754_setcx(IEEE754_INVALID_OPERATION);
<------><------><------>return ieee754sp_indef();
<------><------>}
<------><------>break;
<------>}
 
<------>ix = x.bits;
 
<------>/* normalize x */
<------>m = (ix >> 23);
<------>if (m == 0) {		/* subnormal x */
<------><------>for (i = 0; (ix & 0x00800000) == 0; i++)
<------><------><------>ix <<= 1;
<------><------>m -= i - 1;
<------>}
<------>m -= 127;		/* unbias exponent */
<------>ix = (ix & 0x007fffff) | 0x00800000;
<------>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;
<------>s = 0;
<------>q = 0;			/* q = sqrt(x) */
<------>r = 0x01000000;		/* 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;
<------>}
 
<------>if (ix != 0) {
<------><------>ieee754_setcx(IEEE754_INEXACT);
<------><------>switch (ieee754_csr.rm) {
<------><------>case FPU_CSR_RU:
<------><------><------>q += 2;
<------><------><------>break;
<------><------>case FPU_CSR_RN:
<------><------><------>q += (q & 1);
<------><------><------>break;
<------><------>}
<------>}
<------>ix = (q >> 1) + 0x3f000000;
<------>ix += (m << 23);
<------>x.bits = ix;
<------>return x;
}