1 files changed, 154 insertions, 92 deletions

diff --git a/arch/mips/math-emu/dp_maddf.c b/arch/mips/math-emu/dp_maddf.c
index caa62f20a888..e0d9be5fbf4c 100644
--- a/arch/mips/math-emu/dp_maddf.c
+++ b/arch/mips/math-emu/dp_maddf.c
@@ -14,22 +14,45 @@
 
 #include "ieee754dp.h"
 
-enum maddf_flags {
-	maddf_negate_product	= 1 << 0,
-};
+
+/* 128 bits shift right logical with rounding. */
+void srl128(u64 *hptr, u64 *lptr, int count)
+{
+	u64 low;
+
+	if (count >= 128) {
+		*lptr = *hptr != 0 || *lptr != 0;
+		*hptr = 0;
+	} else if (count >= 64) {
+		if (count == 64) {
+			*lptr = *hptr | (*lptr != 0);
+		} else {
+			low = *lptr;
+			*lptr = *hptr >> (count - 64);
+			*lptr |= (*hptr << (128 - count)) != 0 || low != 0;
+		}
+		*hptr = 0;
+	} else {
+		low = *lptr;
+		*lptr = low >> count | *hptr << (64 - count);
+		*lptr |= (low << (64 - count)) != 0;
+		*hptr = *hptr >> count;
+	}
+}
 
 static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 				 union ieee754dp y, enum maddf_flags flags)
 {
 	int re;
 	int rs;
-	u64 rm;
 	unsigned lxm;
 	unsigned hxm;
 	unsigned lym;
 	unsigned hym;
 	u64 lrm;
 	u64 hrm;
+	u64 lzm;
+	u64 hzm;
 	u64 t;
 	u64 at;
 	int s;
@@ -48,52 +71,34 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 
 	ieee754_clearcx();
 
-	switch (zc) {
-	case IEEE754_CLASS_SNAN:
-		ieee754_setcx(IEEE754_INVALID_OPERATION);
+	/*
+	 * Handle the cases when at least one of x, y or z is a NaN.
+	 * Order of precedence is sNaN, qNaN and z, x, y.
+	 */
+	if (zc == IEEE754_CLASS_SNAN)
 		return ieee754dp_nanxcpt(z);
-	case IEEE754_CLASS_DNORM:
-		DPDNORMZ;
-	/* QNAN and ZERO cases are handled separately below */
-	}
-
-	switch (CLPAIR(xc, yc)) {
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
-		return ieee754dp_nanxcpt(y);
-
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
-	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
+	if (xc == IEEE754_CLASS_SNAN)
 		return ieee754dp_nanxcpt(x);
-
-	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
+	if (yc == IEEE754_CLASS_SNAN)
+		return ieee754dp_nanxcpt(y);
+	if (zc == IEEE754_CLASS_QNAN)
+		return z;
+	if (xc == IEEE754_CLASS_QNAN)
+		return x;
+	if (yc == IEEE754_CLASS_QNAN)
 		return y;
 
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
-	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
-		return x;
+	if (zc == IEEE754_CLASS_DNORM)
+		DPDNORMZ;
+	/* ZERO z cases are handled separately below */
 
+	switch (CLPAIR(xc, yc)) {
 
 	/*
 	 * Infinity handling
 	 */
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
 		ieee754_setcx(IEEE754_INVALID_OPERATION);
 		return ieee754dp_indef();
 
@@ -102,9 +107,27 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
-		return ieee754dp_inf(xs ^ ys);
+		if ((zc == IEEE754_CLASS_INF) &&
+		    ((!(flags & MADDF_NEGATE_PRODUCT) && (zs != (xs ^ ys))) ||
+		     ((flags & MADDF_NEGATE_PRODUCT) && (zs == (xs ^ ys))))) {
+			/*
+			 * Cases of addition of infinities with opposite signs
+			 * or subtraction of infinities with same signs.
+			 */
+			ieee754_setcx(IEEE754_INVALID_OPERATION);
+			return ieee754dp_indef();
+		}
+		/*
+		 * z is here either not an infinity, or an infinity having the
+		 * same sign as product (x*y) (in case of MADDF.D instruction)
+		 * or product -(x*y) (in MSUBF.D case). The result must be an
+		 * infinity, and its sign is determined only by the value of
+		 * (flags & MADDF_NEGATE_PRODUCT) and the signs of x and y.
+		 */
+		if (flags & MADDF_NEGATE_PRODUCT)
+			return ieee754dp_inf(1 ^ (xs ^ ys));
+		else
+			return ieee754dp_inf(xs ^ ys);
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
@@ -113,32 +136,42 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
 		if (zc == IEEE754_CLASS_INF)
 			return ieee754dp_inf(zs);
-		/* Multiplication is 0 so just return z */
+		if (zc == IEEE754_CLASS_ZERO) {
+			/* Handle cases +0 + (-0) and similar ones. */
+			if ((!(flags & MADDF_NEGATE_PRODUCT)
+					&& (zs == (xs ^ ys))) ||
+			    ((flags & MADDF_NEGATE_PRODUCT)
+					&& (zs != (xs ^ ys))))
+				/*
+				 * Cases of addition of zeros of equal signs
+				 * or subtraction of zeroes of opposite signs.
+				 * The sign of the resulting zero is in any
+				 * such case determined only by the sign of z.
+				 */
+				return z;
+
+			return ieee754dp_zero(ieee754_csr.rm == FPU_CSR_RD);
+		}
+		/* x*y is here 0, and z is not 0, so just return z */
 		return z;
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		DPDNORMX;
 
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
-		else if (zc == IEEE754_CLASS_INF)
+		if (zc == IEEE754_CLASS_INF)
 			return ieee754dp_inf(zs);
 		DPDNORMY;
 		break;
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
-		else if (zc == IEEE754_CLASS_INF)
+		if (zc == IEEE754_CLASS_INF)
 			return ieee754dp_inf(zs);
 		DPDNORMX;
 		break;
 
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
-		if (zc == IEEE754_CLASS_QNAN)
-			return z;
-		else if (zc == IEEE754_CLASS_INF)
+		if (zc == IEEE754_CLASS_INF)
 			return ieee754dp_inf(zs);
 		/* fall through to real computations */
 	}
@@ -157,7 +190,7 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 
 	re = xe + ye;
 	rs = xs ^ ys;
-	if (flags & maddf_negate_product)
+	if (flags & MADDF_NEGATE_PRODUCT)
 		rs ^= 1;
 
 	/* shunt to top of word */
@@ -165,7 +198,7 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 	ym <<= 64 - (DP_FBITS + 1);
 
 	/*
-	 * Multiply 64 bits xm, ym to give high 64 bits rm with stickness.
+	 * Multiply 64 bits xm and ym to give 128 bits result in hrm:lrm.
 	 */
 
 	/* 32 * 32 => 64 */
@@ -195,81 +228,110 @@ static union ieee754dp _dp_maddf(union ieee754dp z, union ieee754dp x,
 
 	hrm = hrm + (t >> 32);
 
-	rm = hrm | (lrm != 0);
-
-	/*
-	 * Sticky shift down to normal rounding precision.
-	 */
-	if ((s64) rm < 0) {
-		rm = (rm >> (64 - (DP_FBITS + 1 + 3))) |
-		     ((rm << (DP_FBITS + 1 + 3)) != 0);
+	/* Put explicit bit at bit 126 if necessary */
+	if ((int64_t)hrm < 0) {
+		lrm = (hrm << 63) | (lrm >> 1);
+		hrm = hrm >> 1;
 		re++;
-	} else {
-		rm = (rm >> (64 - (DP_FBITS + 1 + 3 + 1))) |
-		     ((rm << (DP_FBITS + 1 + 3 + 1)) != 0);
 	}
-	assert(rm & (DP_HIDDEN_BIT << 3));
 
-	if (zc == IEEE754_CLASS_ZERO)
-		return ieee754dp_format(rs, re, rm);
+	assert(hrm & (1 << 62));
 
-	/* And now the addition */
-	assert(zm & DP_HIDDEN_BIT);
+	if (zc == IEEE754_CLASS_ZERO) {
+		/*
+		 * Move explicit bit from bit 126 to bit 55 since the
+		 * ieee754dp_format code expects the mantissa to be
+		 * 56 bits wide (53 + 3 rounding bits).
+		 */
+		srl128(&hrm, &lrm, (126 - 55));
+		return ieee754dp_format(rs, re, lrm);
+	}
 
-	/*
-	 * Provide guard,round and stick bit space.
-	 */
-	zm <<= 3;
+	/* Move explicit bit from bit 52 to bit 126 */
+	lzm = 0;
+	hzm = zm << 10;
+	assert(hzm & (1 << 62));
 
+	/* Make the exponents the same */
 	if (ze > re) {
 		/*
 		 * Have to shift y fraction right to align.
 		 */
 		s = ze - re;
-		rm = XDPSRS(rm, s);
+		srl128(&hrm, &lrm, s);
 		re += s;
 	} else if (re > ze) {
 		/*
 		 * Have to shift x fraction right to align.
 		 */
 		s = re - ze;
-		zm = XDPSRS(zm, s);
+		srl128(&hzm, &lzm, s);
 		ze += s;
 	}
 	assert(ze == re);
 	assert(ze <= DP_EMAX);
 
+	/* Do the addition */
 	if (zs == rs) {
 		/*
-		 * Generate 28 bit result of adding two 27 bit numbers
-		 * leaving result in xm, xs and xe.
+		 * Generate 128 bit result by adding two 127 bit numbers
+		 * leaving result in hzm:lzm, zs and ze.
 		 */
-		zm = zm + rm;
-
-		if (zm >> (DP_FBITS + 1 + 3)) { /* carry out */
-			zm = XDPSRS1(zm);
+		hzm = hzm + hrm + (lzm > (lzm + lrm));
+		lzm = lzm + lrm;
+		if ((int64_t)hzm < 0) {        /* carry out */
+			srl128(&hzm, &lzm, 1);
 			ze++;
 		}
 	} else {
-		if (zm >= rm) {
-			zm = zm - rm;
+		if (hzm > hrm || (hzm == hrm && lzm >= lrm)) {
+			hzm = hzm - hrm - (lzm < lrm);
+			lzm = lzm - lrm;
 		} else {
-			zm = rm - zm;
+			hzm = hrm - hzm - (lrm < lzm);
+			lzm = lrm - lzm;
 			zs = rs;
 		}
-		if (zm == 0)
+		if (lzm == 0 && hzm == 0)
 			return ieee754dp_zero(ieee754_csr.rm == FPU_CSR_RD);
 
 		/*
-		 * Normalize to rounding precision.
+		 * Put explicit bit at bit 126 if necessary.
 		 */
-		while ((zm >> (DP_FBITS + 3)) == 0) {
-			zm <<= 1;
-			ze--;
+		if (hzm == 0) {
+			/* left shift by 63 or 64 bits */
+			if ((int64_t)lzm < 0) {
+				/* MSB of lzm is the explicit bit */
+				hzm = lzm >> 1;
+				lzm = lzm << 63;
+				ze -= 63;
+			} else {
+				hzm = lzm;
+				lzm = 0;
+				ze -= 64;
+			}
+		}
+
+		t = 0;
+		while ((hzm >> (62 - t)) == 0)
+			t++;
+
+		assert(t <= 62);
+		if (t) {
+			hzm = hzm << t | lzm >> (64 - t);
+			lzm = lzm << t;
+			ze -= t;
 		}
 	}
 
-	return ieee754dp_format(zs, ze, zm);
+	/*
+	 * Move explicit bit from bit 126 to bit 55 since the
+	 * ieee754dp_format code expects the mantissa to be
+	 * 56 bits wide (53 + 3 rounding bits).
+	 */
+	srl128(&hzm, &lzm, (126 - 55));
+
+	return ieee754dp_format(zs, ze, lzm);
 }
 
 union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
@@ -281,5 +343,5 @@ union ieee754dp ieee754dp_maddf(union ieee754dp z, union ieee754dp x,
 union ieee754dp ieee754dp_msubf(union ieee754dp z, union ieee754dp x,
 				union ieee754dp y)
 {
-	return _dp_maddf(z, x, y, maddf_negate_product);
+	return _dp_maddf(z, x, y, MADDF_NEGATE_PRODUCT);
 }