1 files changed, 196 insertions, 0 deletions

diff --git a/arch/mips/math-emu/ieee754sp.c b/arch/mips/math-emu/ieee754sp.c
new file mode 100644
index 000000000..0b6267bc8
--- /dev/null
+++ b/arch/mips/math-emu/ieee754sp.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* IEEE754 floating point arithmetic
+ * single precision
+ */
+/*
+ * MIPS floating point support
+ * Copyright (C) 1994-2000 Algorithmics Ltd.
+ */
+
+#include <linux/compiler.h>
+
+#include "ieee754sp.h"
+
+int ieee754sp_class(union ieee754sp x)
+{
+        COMPXSP;
+        EXPLODEXSP;
+        return xc;
+}
+
+static inline int ieee754sp_isnan(union ieee754sp x)
+{
+        return ieee754_class_nan(ieee754sp_class(x));
+}
+
+static inline int ieee754sp_issnan(union ieee754sp x)
+{
+        int qbit;
+
+        assert(ieee754sp_isnan(x));
+        qbit = (SPMANT(x) & SP_MBIT(SP_FBITS - 1)) == SP_MBIT(SP_FBITS - 1);
+        return ieee754_csr.nan2008 ^ qbit;
+}
+
+
+/*
+ * Raise the Invalid Operation IEEE 754 exception
+ * and convert the signaling NaN supplied to a quiet NaN.
+ */
+union ieee754sp __cold ieee754sp_nanxcpt(union ieee754sp r)
+{
+        assert(ieee754sp_issnan(r));
+
+        ieee754_setcx(IEEE754_INVALID_OPERATION);
+        if (ieee754_csr.nan2008) {
+                SPMANT(r) |= SP_MBIT(SP_FBITS - 1);
+        } else {
+                SPMANT(r) &= ~SP_MBIT(SP_FBITS - 1);
+                if (!ieee754sp_isnan(r))
+                        SPMANT(r) |= SP_MBIT(SP_FBITS - 2);
+        }
+
+        return r;
+}
+
+static unsigned int ieee754sp_get_rounding(int sn, unsigned int xm)
+{
+        /* inexact must round of 3 bits
+         */
+        if (xm & (SP_MBIT(3) - 1)) {
+                switch (ieee754_csr.rm) {
+                case FPU_CSR_RZ:
+                        break;
+                case FPU_CSR_RN:
+                        xm += 0x3 + ((xm >> 3) & 1);
+                        /* xm += (xm&0x8)?0x4:0x3 */
+                        break;
+                case FPU_CSR_RU:        /* toward +Infinity */
+                        if (!sn)        /* ?? */
+                                xm += 0x8;
+                        break;
+                case FPU_CSR_RD:        /* toward -Infinity */
+                        if (sn) /* ?? */
+                                xm += 0x8;
+                        break;
+                }
+        }
+        return xm;
+}
+
+
+/* generate a normal/denormal number with over,under handling
+ * sn is sign
+ * xe is an unbiased exponent
+ * xm is 3bit extended precision value.
+ */
+union ieee754sp ieee754sp_format(int sn, int xe, unsigned int xm)
+{
+        assert(xm);             /* we don't gen exact zeros (probably should) */
+
+        assert((xm >> (SP_FBITS + 1 + 3)) == 0);        /* no excess */
+        assert(xm & (SP_HIDDEN_BIT << 3));
+
+        if (xe < SP_EMIN) {
+                /* strip lower bits */
+                int es = SP_EMIN - xe;
+
+                if (ieee754_csr.nod) {
+                        ieee754_setcx(IEEE754_UNDERFLOW);
+                        ieee754_setcx(IEEE754_INEXACT);
+
+                        switch(ieee754_csr.rm) {
+                        case FPU_CSR_RN:
+                        case FPU_CSR_RZ:
+                                return ieee754sp_zero(sn);
+                        case FPU_CSR_RU:      /* toward +Infinity */
+                                if (sn == 0)
+                                        return ieee754sp_min(0);
+                                else
+                                        return ieee754sp_zero(1);
+                        case FPU_CSR_RD:      /* toward -Infinity */
+                                if (sn == 0)
+                                        return ieee754sp_zero(0);
+                                else
+                                        return ieee754sp_min(1);
+                        }
+                }
+
+                if (xe == SP_EMIN - 1 &&
+                    ieee754sp_get_rounding(sn, xm) >> (SP_FBITS + 1 + 3))
+                {
+                        /* Not tiny after rounding */
+                        ieee754_setcx(IEEE754_INEXACT);
+                        xm = ieee754sp_get_rounding(sn, xm);
+                        xm >>= 1;
+                        /* Clear grs bits */
+                        xm &= ~(SP_MBIT(3) - 1);
+                        xe++;
+                } else {
+                        /* sticky right shift es bits
+                         */
+                        xm = XSPSRS(xm, es);
+                        xe += es;
+                        assert((xm & (SP_HIDDEN_BIT << 3)) == 0);
+                        assert(xe == SP_EMIN);
+                }
+        }
+        if (xm & (SP_MBIT(3) - 1)) {
+                ieee754_setcx(IEEE754_INEXACT);
+                if ((xm & (SP_HIDDEN_BIT << 3)) == 0) {
+                        ieee754_setcx(IEEE754_UNDERFLOW);
+                }
+
+                /* inexact must round of 3 bits
+                 */
+                xm = ieee754sp_get_rounding(sn, xm);
+                /* adjust exponent for rounding add overflowing
+                 */
+                if (xm >> (SP_FBITS + 1 + 3)) {
+                        /* add causes mantissa overflow */
+                        xm >>= 1;
+                        xe++;
+                }
+        }
+        /* strip grs bits */
+        xm >>= 3;
+
+        assert((xm >> (SP_FBITS + 1)) == 0);    /* no excess */
+        assert(xe >= SP_EMIN);
+
+        if (xe > SP_EMAX) {
+                ieee754_setcx(IEEE754_OVERFLOW);
+                ieee754_setcx(IEEE754_INEXACT);
+                /* -O can be table indexed by (rm,sn) */
+                switch (ieee754_csr.rm) {
+                case FPU_CSR_RN:
+                        return ieee754sp_inf(sn);
+                case FPU_CSR_RZ:
+                        return ieee754sp_max(sn);
+                case FPU_CSR_RU:        /* toward +Infinity */
+                        if (sn == 0)
+                                return ieee754sp_inf(0);
+                        else
+                                return ieee754sp_max(1);
+                case FPU_CSR_RD:        /* toward -Infinity */
+                        if (sn == 0)
+                                return ieee754sp_max(0);
+                        else
+                                return ieee754sp_inf(1);
+                }
+        }
+        /* gen norm/denorm/zero */
+
+        if ((xm & SP_HIDDEN_BIT) == 0) {
+                /* we underflow (tiny/zero) */
+                assert(xe == SP_EMIN);
+                if (ieee754_csr.mx & IEEE754_UNDERFLOW)
+                        ieee754_setcx(IEEE754_UNDERFLOW);
+                return buildsp(sn, SP_EMIN - 1 + SP_EBIAS, xm);
+        } else {
+                assert((xm >> (SP_FBITS + 1)) == 0);    /* no excess */
+                assert(xm & SP_HIDDEN_BIT);
+
+                return buildsp(sn, xe + SP_EBIAS, xm & ~SP_HIDDEN_BIT);
+        }
+}