COMPILER_RT_ABI dst_t
__truncdfsf2(src_t a) {
// Various constants whose values follow from the type parameters.
// Any reasonable optimizer will fold and propagate all of these.
const int srcBits = sizeof(src_t)*CHAR_BIT;
const int srcExpBits = srcBits - srcSigBits - 1;
const int srcInfExp = (1 << srcExpBits) - 1;
const int srcExpBias = srcInfExp >> 1;
const src_rep_t srcMinNormal = SRC_REP_C(1) << srcSigBits;
const src_rep_t significandMask = srcMinNormal - 1;
const src_rep_t srcInfinity = (src_rep_t)srcInfExp << srcSigBits;
const src_rep_t srcSignMask = SRC_REP_C(1) << (srcSigBits + srcExpBits);
const src_rep_t srcAbsMask = srcSignMask - 1;
const src_rep_t roundMask = (SRC_REP_C(1) << (srcSigBits - dstSigBits)) - 1;
const src_rep_t halfway = SRC_REP_C(1) << (srcSigBits - dstSigBits - 1);
const int dstBits = sizeof(dst_t)*CHAR_BIT;
const int dstExpBits = dstBits - dstSigBits - 1;
const int dstInfExp = (1 << dstExpBits) - 1;
const int dstExpBias = dstInfExp >> 1;
const int underflowExponent = srcExpBias + 1 - dstExpBias;
const int overflowExponent = srcExpBias + dstInfExp - dstExpBias;
const src_rep_t underflow = (src_rep_t)underflowExponent << srcSigBits;
const src_rep_t overflow = (src_rep_t)overflowExponent << srcSigBits;
const dst_rep_t dstQNaN = DST_REP_C(1) << (dstSigBits - 1);
const dst_rep_t dstNaNCode = dstQNaN - 1;
// Break a into a sign and representation of the absolute value
const src_rep_t aRep = srcToRep(a);
const src_rep_t aAbs = aRep & srcAbsMask;
const src_rep_t sign = aRep & srcSignMask;
dst_rep_t absResult;
if (aAbs - underflow < aAbs - overflow) {
// The exponent of a is within the range of normal numbers in the
// destination format. We can convert by simply right-shifting with
// rounding and adjusting the exponent.
absResult = aAbs >> (srcSigBits - dstSigBits);
absResult -= (dst_rep_t)(srcExpBias - dstExpBias) << dstSigBits;
const src_rep_t roundBits = aAbs & roundMask;
// Round to nearest
if (roundBits > halfway)
absResult++;
// Ties to even
else if (roundBits == halfway)
absResult += absResult & 1;
}
dst_t __extendsfdf2(src_t a) {
// Various constants whose values follow from the type parameters.
// Any reasonable optimizer will fold and propagate all of these.
const int srcBits = sizeof(src_t)*CHAR_BIT;
const int srcExpBits = srcBits - srcSigBits - 1;
const int srcInfExp = (1 << srcExpBits) - 1;
const int srcExpBias = srcInfExp >> 1;
const src_rep_t srcMinNormal = SRC_REP_C(1) << srcSigBits;
const src_rep_t srcInfinity = (src_rep_t)srcInfExp << srcSigBits;
const src_rep_t srcSignMask = SRC_REP_C(1) << (srcSigBits + srcExpBits);
const src_rep_t srcAbsMask = srcSignMask - 1;
const src_rep_t srcQNaN = SRC_REP_C(1) << (srcSigBits - 1);
const src_rep_t srcNaNCode = srcQNaN - 1;
const int dstBits = sizeof(dst_t)*CHAR_BIT;
const int dstExpBits = dstBits - dstSigBits - 1;
const int dstInfExp = (1 << dstExpBits) - 1;
const int dstExpBias = dstInfExp >> 1;
const dst_rep_t dstMinNormal = DST_REP_C(1) << dstSigBits;
// Break a into a sign and representation of the absolute value
const src_rep_t aRep = srcToRep(a);
const src_rep_t aAbs = aRep & srcAbsMask;
const src_rep_t sign = aRep & srcSignMask;
dst_rep_t absResult;
if (aAbs - srcMinNormal < srcInfinity - srcMinNormal) {
// a is a normal number.
// Extend to the destination type by shifting the significand and
// exponent into the proper position and rebiasing the exponent.
absResult = (dst_rep_t)aAbs << (dstSigBits - srcSigBits);
absResult += (dst_rep_t)(dstExpBias - srcExpBias) << dstSigBits;
}
else if (aAbs >= srcInfinity) {
// a is NaN or infinity.
// Conjure the result by beginning with infinity, then setting the qNaN
// bit (if needed) and right-aligning the rest of the trailing NaN
// payload field.
absResult = (dst_rep_t)dstInfExp << dstSigBits;
absResult |= (dst_rep_t)(aAbs & srcQNaN) << (dstSigBits - srcSigBits);
absResult |= aAbs & srcNaNCode;
}
else if (aAbs) {
// a is denormal.
// renormalize the significand and clear the leading bit, then insert
// the correct adjusted exponent in the destination type.
const int scale = src_rep_t_clz(aAbs) - src_rep_t_clz(srcMinNormal);
absResult = (dst_rep_t)aAbs << (dstSigBits - srcSigBits + scale);
absResult ^= dstMinNormal;
const int resultExponent = dstExpBias - srcExpBias - scale + 1;
absResult |= (dst_rep_t)resultExponent << dstSigBits;
}
else {
// a is zero.
absResult = 0;
}
// Apply the signbit to (dst_t)abs(a).
const dst_rep_t result = absResult | (dst_rep_t)sign << (dstBits - srcBits);
return dstFromRep(result);
}
