Upstream version 2.08rc7

1 files changed, 956 insertions, 0 deletions

diff --git a/float.c b/float.c
new file mode 100644
index 0000000..7a4f8cb
--- /dev/null
+++ b/float.c
@@ -0,0 +1,956 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 1996-2009 The NASM Authors - All Rights Reserved
+ *   See the file AUTHORS included with the NASM distribution for
+ *   the specific copyright holders.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following
+ *   conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ *     copyright notice, this list of conditions and the following
+ *     disclaimer in the documentation and/or other materials provided
+ *     with the distribution.
+ *
+ *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * float.c     floating-point constant support for the Netwide Assembler
+ */
+
+#include "compiler.h"
+
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+
+#include "nasm.h"
+#include "float.h"
+
+/*
+ * -----------------
+ *  local variables
+ * -----------------
+ */
+static efunc error;
+static bool daz = false;        /* denormals as zero */
+static enum float_round rc = FLOAT_RC_NEAR;     /* rounding control */
+
+/*
+ * -----------
+ *  constants
+ * -----------
+ */
+
+/* "A limb is like a digit but bigger */
+typedef uint32_t fp_limb;
+typedef uint64_t fp_2limb;
+
+#define LIMB_BITS       32
+#define LIMB_BYTES      (LIMB_BITS/8)
+#define LIMB_TOP_BIT    ((fp_limb)1 << (LIMB_BITS-1))
+#define LIMB_MASK       ((fp_limb)(~0))
+#define LIMB_ALL_BYTES  ((fp_limb)0x01010101)
+#define LIMB_BYTE(x)    ((x)*LIMB_ALL_BYTES)
+
+/* 112 bits + 64 bits for accuracy + 16 bits for rounding */
+#define MANT_LIMBS 6
+
+/* 52 digits fit in 176 bits because 10^53 > 2^176 > 10^52 */
+#define MANT_DIGITS 52
+
+/* the format and the argument list depend on MANT_LIMBS */
+#define MANT_FMT "%08x_%08x_%08x_%08x_%08x_%08x"
+#define MANT_ARG SOME_ARG(mant, 0)
+
+#define SOME_ARG(a,i) (a)[(i)+0], (a)[(i)+1], (a)[(i)+2], \
+                      (a)[(i)+3], (a)[(i)+4], (a)[(i)+5]
+
+/*
+ * ---------------------------------------------------------------------------
+ *  emit a printf()-like debug message... but only if DEBUG_FLOAT was defined
+ * ---------------------------------------------------------------------------
+ */
+
+#ifdef DEBUG_FLOAT
+#define dprintf(x) printf x
+#else
+#define dprintf(x) do { } while (0)
+#endif
+
+/*
+ * ---------------------------------------------------------------------------
+ *  multiply
+ * ---------------------------------------------------------------------------
+ */
+static int float_multiply(fp_limb *to, fp_limb *from)
+{
+    fp_2limb temp[MANT_LIMBS * 2];
+    int i, j;
+
+    /*
+     * guaranteed that top bit of 'from' is set -- so we only have
+     * to worry about _one_ bit shift to the left
+     */
+    dprintf(("%s=" MANT_FMT "\n", "mul1", SOME_ARG(to, 0)));
+    dprintf(("%s=" MANT_FMT "\n", "mul2", SOME_ARG(from, 0)));
+
+    memset(temp, 0, sizeof temp);
+
+    for (i = 0; i < MANT_LIMBS; i++) {
+        for (j = 0; j < MANT_LIMBS; j++) {
+            fp_2limb n;
+            n = (fp_2limb) to[i] * (fp_2limb) from[j];
+            temp[i + j] += n >> LIMB_BITS;
+            temp[i + j + 1] += (fp_limb)n;
+        }
+    }
+
+    for (i = MANT_LIMBS * 2; --i;) {
+        temp[i - 1] += temp[i] >> LIMB_BITS;
+        temp[i] &= LIMB_MASK;
+    }
+
+    dprintf(("%s=" MANT_FMT "_" MANT_FMT "\n", "temp", SOME_ARG(temp, 0),
+             SOME_ARG(temp, MANT_LIMBS)));
+
+    if (temp[0] & LIMB_TOP_BIT) {
+        for (i = 0; i < MANT_LIMBS; i++) {
+            to[i] = temp[i] & LIMB_MASK;
+        }
+        dprintf(("%s=" MANT_FMT " (%i)\n", "prod", SOME_ARG(to, 0), 0));
+        return 0;
+    } else {
+        for (i = 0; i < MANT_LIMBS; i++) {
+            to[i] = (temp[i] << 1) + !!(temp[i + 1] & LIMB_TOP_BIT);
+        }
+        dprintf(("%s=" MANT_FMT " (%i)\n", "prod", SOME_ARG(to, 0), -1));
+        return -1;
+    }
+}
+
+/*
+ * ---------------------------------------------------------------------------
+ *  read an exponent; returns INT32_MAX on error
+ * ---------------------------------------------------------------------------
+ */
+static int32_t read_exponent(const char *string, int32_t max)
+{
+    int32_t i = 0;
+    bool neg = false;
+
+    if (*string == '+') {
+        string++;
+    } else if (*string == '-') {
+        neg = true;
+        string++;
+    }
+    while (*string) {
+        if (*string >= '0' && *string <= '9') {
+            i = (i * 10) + (*string - '0');
+
+            /*
+             * To ensure that underflows and overflows are
+             * handled properly we must avoid wraparounds of
+             * the signed integer value that is used to hold
+             * the exponent. Therefore we cap the exponent at
+             * +/-5000, which is slightly more/less than
+             * what's required for normal and denormal numbers
+             * in single, double, and extended precision, but
+             * sufficient to avoid signed integer wraparound.
+             */
+            if (i > max)
+                i = max;
+        } else if (*string == '_') {
+            /* do nothing */
+        } else {
+            error(ERR_NONFATAL|ERR_PASS1,
+                  "invalid character in floating-point constant %s: '%c'",
+                  "exponent", *string);
+            return INT32_MAX;
+        }
+        string++;
+    }
+
+    return neg ? -i : i;
+}
+
+/*
+ * ---------------------------------------------------------------------------
+ *  convert
+ * ---------------------------------------------------------------------------
+ */
+static bool ieee_flconvert(const char *string, fp_limb *mant,
+                           int32_t * exponent)
+{
+    char digits[MANT_DIGITS];
+    char *p, *q, *r;
+    fp_limb mult[MANT_LIMBS], bit;
+    fp_limb *m;
+    int32_t tenpwr, twopwr;
+    int32_t extratwos;
+    bool started, seendot, warned;
+
+    warned = false;
+    p = digits;
+    tenpwr = 0;
+    started = seendot = false;
+
+    while (*string && *string != 'E' && *string != 'e') {
+        if (*string == '.') {
+            if (!seendot) {
+                seendot = true;
+            } else {
+                error(ERR_NONFATAL|ERR_PASS1,
+                      "too many periods in floating-point constant");
+                return false;
+            }
+        } else if (*string >= '0' && *string <= '9') {
+            if (*string == '0' && !started) {
+                if (seendot) {
+                    tenpwr--;
+                }
+            } else {
+                started = true;
+                if (p < digits + sizeof(digits)) {
+                    *p++ = *string - '0';
+                } else {
+                    if (!warned) {
+                        error(ERR_WARNING|ERR_WARN_FL_TOOLONG|ERR_PASS1,
+                              "floating-point constant significand contains "
+                              "more than %i digits", MANT_DIGITS);
+                        warned = true;
+                    }
+                }
+                if (!seendot) {
+                    tenpwr++;
+                }
+            }
+        } else if (*string == '_') {
+            /* do nothing */
+        } else {
+            error(ERR_NONFATAL|ERR_PASS1,
+                  "invalid character in floating-point constant %s: '%c'",
+                  "significand", *string);
+            return false;
+        }
+        string++;
+    }
+
+    if (*string) {
+        int32_t e;
+
+        string++;               /* eat the E */
+        e = read_exponent(string, 5000);
+        if (e == INT32_MAX)
+            return false;
+        tenpwr += e;
+    }
+
+    /*
+     * At this point, the memory interval [digits,p) contains a
+     * series of decimal digits zzzzzzz, such that our number X
+     * satisfies X = 0.zzzzzzz * 10^tenpwr.
+     */
+    q = digits;
+    dprintf(("X = 0."));
+    while (q < p) {
+        dprintf(("%c", *q + '0'));
+        q++;
+    }
+    dprintf((" * 10^%i\n", tenpwr));
+
+    /*
+     * Now convert [digits,p) to our internal representation.
+     */
+    bit = LIMB_TOP_BIT;
+    for (m = mant; m < mant + MANT_LIMBS; m++) {
+        *m = 0;
+    }
+    m = mant;
+    q = digits;
+    started = false;
+    twopwr = 0;
+    while (m < mant + MANT_LIMBS) {
+        fp_limb carry = 0;
+        while (p > q && !p[-1]) {
+            p--;
+        }
+        if (p <= q) {
+            break;
+        }
+        for (r = p; r-- > q;) {
+            int32_t i;
+            i = 2 * *r + carry;
+            if (i >= 10) {
+                carry = 1;
+                i -= 10;
+            } else {
+                carry = 0;
+            }
+            *r = i;
+        }
+        if (carry) {
+            *m |= bit;
+            started = true;
+        }
+        if (started) {
+            if (bit == 1) {
+                bit = LIMB_TOP_BIT;
+                m++;
+            } else {
+                bit >>= 1;
+            }
+        } else {
+            twopwr--;
+        }
+    }
+    twopwr += tenpwr;
+
+    /*
+     * At this point, the 'mant' array contains the first frac-
+     * tional places of a base-2^16 real number which when mul-
+     * tiplied by 2^twopwr and 5^tenpwr gives X.
+     */
+    dprintf(("X = " MANT_FMT " * 2^%i * 5^%i\n", MANT_ARG, twopwr,
+             tenpwr));
+
+    /*
+     * Now multiply 'mant' by 5^tenpwr.
+     */
+    if (tenpwr < 0) {           /* mult = 5^-1 = 0.2 */
+        for (m = mult; m < mult + MANT_LIMBS - 1; m++) {
+            *m = LIMB_BYTE(0xcc);
+        }
+        mult[MANT_LIMBS - 1] = LIMB_BYTE(0xcc)+1;
+        extratwos = -2;
+        tenpwr = -tenpwr;
+
+        /*
+         * If tenpwr was 1000...000b, then it becomes 1000...000b. See
+         * the "ANSI C" comment below for more details on that case.
+         *
+         * Because we already truncated tenpwr to +5000...-5000 inside
+         * the exponent parsing code, this shouldn't happen though.
+         */
+    } else if (tenpwr > 0) {    /* mult = 5^+1 = 5.0 */
+        mult[0] = (fp_limb)5 << (LIMB_BITS-3); /* 0xA000... */
+        for (m = mult + 1; m < mult + MANT_LIMBS; m++) {
+            *m = 0;
+        }
+        extratwos = 3;
+    } else {
+        extratwos = 0;
+    }
+    while (tenpwr) {
+        dprintf(("loop=" MANT_FMT " * 2^%i * 5^%i (%i)\n", MANT_ARG,
+                 twopwr, tenpwr, extratwos));
+        if (tenpwr & 1) {
+            dprintf(("mant*mult\n"));
+            twopwr += extratwos + float_multiply(mant, mult);
+        }
+        dprintf(("mult*mult\n"));
+        extratwos = extratwos * 2 + float_multiply(mult, mult);
+        tenpwr >>= 1;
+
+        /*
+         * In ANSI C, the result of right-shifting a signed integer is
+         * considered implementation-specific. To ensure that the loop
+         * terminates even if tenpwr was 1000...000b to begin with, we
+         * manually clear the MSB, in case a 1 was shifted in.
+         *
+         * Because we already truncated tenpwr to +5000...-5000 inside
+         * the exponent parsing code, this shouldn't matter; neverthe-
+         * less it is the right thing to do here.
+         */
+        tenpwr &= (uint32_t) - 1 >> 1;
+    }
+
+    /*
+     * At this point, the 'mant' array contains the first frac-
+     * tional places of a base-2^16 real number in [0.5,1) that
+     * when multiplied by 2^twopwr gives X. Or it contains zero
+     * of course. We are done.
+     */
+    *exponent = twopwr;
+    return true;
+}
+
+/*
+ * ---------------------------------------------------------------------------
+ *  operations of specific bits
+ * ---------------------------------------------------------------------------
+ */
+
+/* Set a bit, using *bigendian* bit numbering (0 = MSB) */
+static void set_bit(fp_limb *mant, int bit)
+{
+    mant[bit/LIMB_BITS] |= LIMB_TOP_BIT >> (bit & (LIMB_BITS-1));
+}
+
+/* Test a single bit */
+static int test_bit(const fp_limb *mant, int bit)
+{
+    return (mant[bit/LIMB_BITS] >> (~bit & (LIMB_BITS-1))) & 1;
+}
+
+/* Report if the mantissa value is all zero */
+static bool is_zero(const fp_limb *mant)
+{
+    int i;
+
+    for (i = 0; i < MANT_LIMBS; i++)
+        if (mant[i])
+            return false;
+
+    return true;
+}
+
+/*
+ * ---------------------------------------------------------------------------
+ *  round a mantissa off after i words
+ * ---------------------------------------------------------------------------
+ */
+
+#define ROUND_COLLECT_BITS                      \
+    do {                                        \
+        m = mant[i] & (2*bit-1);                \
+        for (j = i+1; j < MANT_LIMBS; j++)      \
+            m = m | mant[j];                    \
+    } while (0)
+
+#define ROUND_ABS_DOWN                          \
+    do {                                        \
+        mant[i] &= ~(bit-1);                    \
+        for (j = i+1; j < MANT_LIMBS; j++)      \
+            mant[j] = 0;                        \
+        return false;                           \
+    } while (0)
+
+#define ROUND_ABS_UP                            \
+    do {                                        \
+        mant[i] = (mant[i] & ~(bit-1)) + bit;   \
+        for (j = i+1; j < MANT_LIMBS; j++)      \
+            mant[j] = 0;                        \
+        while (i > 0 && !mant[i])               \
+            ++mant[--i];                        \
+        return !mant[0];                        \
+    } while (0)
+
+static bool ieee_round(bool minus, fp_limb *mant, int bits)
+{
+    fp_limb m = 0;
+    int32_t j;
+    int i = bits / LIMB_BITS;
+    int p = bits % LIMB_BITS;
+    fp_limb bit = LIMB_TOP_BIT >> p;
+
+    if (rc == FLOAT_RC_NEAR) {
+        if (mant[i] & bit) {
+            mant[i] &= ~bit;
+            ROUND_COLLECT_BITS;
+            mant[i] |= bit;
+            if (m) {
+                ROUND_ABS_UP;
+            } else {
+                if (test_bit(mant, bits-1)) {
+                    ROUND_ABS_UP;
+                } else {
+                    ROUND_ABS_DOWN;
+                }
+            }
+        } else {
+            ROUND_ABS_DOWN;
+        }
+    } else if (rc == FLOAT_RC_ZERO ||
+               rc == (minus ? FLOAT_RC_UP : FLOAT_RC_DOWN)) {
+        ROUND_ABS_DOWN;
+    } else {
+        /* rc == (minus ? FLOAT_RC_DOWN : FLOAT_RC_UP) */
+        /* Round toward +/- infinity */
+        ROUND_COLLECT_BITS;
+        if (m) {
+            ROUND_ABS_UP;
+        } else {
+            ROUND_ABS_DOWN;
+        }
+    }
+    return false;
+}
+
+/* Returns a value >= 16 if not a valid hex digit */
+static unsigned int hexval(char c)
+{
+    unsigned int v = (unsigned char) c;
+
+    if (v >= '0' && v <= '9')
+        return v - '0';
+    else
+        return (v|0x20) - 'a' + 10;
+}
+
+/* Handle floating-point numbers with radix 2^bits and binary exponent */
+static bool ieee_flconvert_bin(const char *string, int bits,
+                               fp_limb *mant, int32_t *exponent)
+{
+    static const int log2tbl[16] =
+        { -1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3 };
+    fp_limb mult[MANT_LIMBS + 1], *mp;
+    int ms;
+    int32_t twopwr;
+    bool seendot, seendigit;
+    unsigned char c;
+    const int radix = 1 << bits;
+    fp_limb v;
+
+    twopwr = 0;
+    seendot = seendigit = false;
+    ms = 0;
+    mp = NULL;
+
+    memset(mult, 0, sizeof mult);
+
+    while ((c = *string++) != '\0') {
+        if (c == '.') {
+            if (!seendot)
+                seendot = true;
+            else {
+                error(ERR_NONFATAL|ERR_PASS1,
+                      "too many periods in floating-point constant");
+                return false;
+            }
+        } else if ((v = hexval(c)) < (unsigned int)radix) {
+            if (!seendigit && v) {
+                int l = log2tbl[v];
+
+                seendigit = true;
+                mp = mult;
+                ms = (LIMB_BITS-1)-l;
+
+                twopwr = seendot ? twopwr-bits+l : l+1-bits;
+            }
+
+            if (seendigit) {
+                if (ms <= 0) {
+                    *mp |= v >> -ms;
+                    mp++;
+                    if (mp > &mult[MANT_LIMBS])
+                        mp = &mult[MANT_LIMBS]; /* Guard slot */
+                    ms += LIMB_BITS;
+                }
+                *mp |= v << ms;
+                ms -= bits;
+
+                if (!seendot)
+                    twopwr += bits;
+            } else {
+                if (seendot)
+                    twopwr -= bits;
+            }
+        } else if (c == 'p' || c == 'P') {
+            int32_t e;
+            e = read_exponent(string, 20000);
+            if (e == INT32_MAX)
+                return false;
+            twopwr += e;
+            break;
+        } else if (c == '_') {
+            /* ignore */
+        } else {
+            error(ERR_NONFATAL|ERR_PASS1,
+                  "floating-point constant: `%c' is invalid character", c);
+            return false;
+        }
+    }
+
+    if (!seendigit) {
+        memset(mant, 0, MANT_LIMBS*sizeof(fp_limb)); /* Zero */
+        *exponent = 0;
+    } else {
+        memcpy(mant, mult, MANT_LIMBS*sizeof(fp_limb));
+        *exponent = twopwr;
+    }
+
+    return true;
+}
+
+/*
+ * Shift a mantissa to the right by i bits.
+ */
+static void ieee_shr(fp_limb *mant, int i)
+{
+    fp_limb n, m;
+    int j = 0;
+    int sr, sl, offs;
+
+    sr = i % LIMB_BITS; sl = LIMB_BITS-sr;
+    offs = i/LIMB_BITS;
+
+    if (sr == 0) {
+        if (offs)
+            for (j = MANT_LIMBS-1; j >= offs; j--)
+                mant[j] = mant[j-offs];
+    } else {
+        n = mant[MANT_LIMBS-1-offs] >> sr;
+        for (j = MANT_LIMBS-1; j > offs; j--) {
+            m = mant[j-offs-1];
+            mant[j] = (m << sl) | n;
+            n = m >> sr;
+        }
+        mant[j--] = n;
+    }
+    while (j >= 0)
+        mant[j--] = 0;
+}
+
+/* Produce standard IEEE formats, with implicit or explicit integer
+   bit; this makes the following assumptions:
+
+   - the sign bit is the MSB, followed by the exponent,
+     followed by the integer bit if present.
+   - the sign bit plus exponent fit in 16 bits.
+   - the exponent bias is 2^(n-1)-1 for an n-bit exponent */
+
+struct ieee_format {
+    int bytes;
+    int mantissa;               /* Fractional bits in the mantissa */
+    int explicit;               /* Explicit integer */
+    int exponent;               /* Bits in the exponent */
+};
+
+/*
+ * The 16- and 128-bit formats are expected to be in IEEE 754r.
+ * AMD SSE5 uses the 16-bit format.
+ *
+ * The 32- and 64-bit formats are the original IEEE 754 formats.
+ *
+ * The 80-bit format is x87-specific, but widely used.
+ *
+ * The 8-bit format appears to be the consensus 8-bit floating-point
+ * format.  It is apparently used in graphics applications.
+ */
+static const struct ieee_format ieee_8   = {  1,   3, 0,  4 };
+static const struct ieee_format ieee_16  = {  2,  10, 0,  5 };
+static const struct ieee_format ieee_32  = {  4,  23, 0,  8 };
+static const struct ieee_format ieee_64  = {  8,  52, 0, 11 };
+static const struct ieee_format ieee_80  = { 10,  63, 1, 15 };
+static const struct ieee_format ieee_128 = { 16, 112, 0, 15 };
+
+/* Types of values we can generate */
+enum floats {
+    FL_ZERO,
+    FL_DENORMAL,
+    FL_NORMAL,
+    FL_INFINITY,
+    FL_QNAN,
+    FL_SNAN
+};
+
+static int to_packed_bcd(const char *str, const char *p,
+                         int s, uint8_t *result,
+                         const struct ieee_format *fmt)
+{
+    int n = 0;
+    char c;
+    int tv = -1;
+
+    if (fmt != &ieee_80) {
+        error(ERR_NONFATAL|ERR_PASS1,
+              "packed BCD requires an 80-bit format");
+        return 0;
+    }
+
+    while (p >= str) {
+        c = *p--;
+        if (c >= '0' && c <= '9') {
+            if (tv < 0) {
+                if (n == 9) {
+                    error(ERR_WARNING|ERR_PASS1,
+                          "packed BCD truncated to 18 digits");
+                }
+                tv = c-'0';
+            } else {
+                if (n < 9)
+                    *result++ = tv + ((c-'0') << 4);
+                n++;
+                tv = -1;
+            }
+        } else if (c == '_') {
+            /* do nothing */
+        } else {
+            error(ERR_NONFATAL|ERR_PASS1,
+                  "invalid character `%c' in packed BCD constant", c);
+            return 0;
+        }
+    }
+    if (tv >= 0) {
+        if (n < 9)
+            *result++ = tv;
+        n++;
+    }
+    while (n < 9) {
+        *result++ = 0;
+        n++;
+    }
+    *result = (s < 0) ? 0x80 : 0;
+
+    return 1;                   /* success */
+}
+
+static int to_float(const char *str, int s, uint8_t *result,
+                    const struct ieee_format *fmt)
+{
+    fp_limb mant[MANT_LIMBS];
+    int32_t exponent = 0;
+    const int32_t expmax = 1 << (fmt->exponent - 1);
+    fp_limb one_mask = LIMB_TOP_BIT >>
+        ((fmt->exponent+fmt->explicit) % LIMB_BITS);
+    const int one_pos = (fmt->exponent+fmt->explicit)/LIMB_BITS;
+    int i;
+    int shift;
+    enum floats type;
+    bool ok;
+    const bool minus = s < 0;
+    const int bits = fmt->bytes * 8;
+    const char *strend;
+
+    if (!str[0]) {
+        error(ERR_PANIC,
+              "internal errror: empty string passed to float_const");
+        return 0;
+    }
+
+    strend = strchr(str, '\0');
+    if (strend[-1] == 'P' || strend[-1] == 'p')
+        return to_packed_bcd(str, strend-2, s, result, fmt);
+
+    if (str[0] == '_') {
+        /* Special tokens */
+
+        switch (str[2]) {
+        case 'n':              /* __nan__ */
+        case 'N':
+        case 'q':              /* __qnan__ */
+        case 'Q':
+            type = FL_QNAN;
+            break;
+        case 's':              /* __snan__ */
+        case 'S':
+            type = FL_SNAN;
+            break;
+        case 'i':              /* __infinity__ */
+        case 'I':
+            type = FL_INFINITY;
+            break;
+        default:
+            error(ERR_NONFATAL|ERR_PASS1,
+                  "internal error: unknown FP constant token `%s'\n", str);
+            type = FL_QNAN;
+            break;
+        }
+    } else {
+        if (str[0] == '0') {
+            switch (str[1]) {
+            case 'x': case 'X':
+            case 'h': case 'H':
+                ok = ieee_flconvert_bin(str+2, 4, mant, &exponent);
+                break;
+            case 'o': case 'O':
+            case 'q': case 'Q':
+                ok = ieee_flconvert_bin(str+2, 3, mant, &exponent);
+                break;
+            case 'b': case 'B':
+            case 'y': case 'Y':
+                ok = ieee_flconvert_bin(str+2, 1, mant, &exponent);
+                break;
+            case 'd': case 'D':
+            case 't': case 'T':
+                ok = ieee_flconvert(str+2, mant, &exponent);
+                break;
+            case 'p': case 'P':
+                return to_packed_bcd(str+2, strend-1, s, result, fmt);
+            default:
+                /* Leading zero was just a zero? */
+                ok = ieee_flconvert(str, mant, &exponent);
+                break;
+            }
+        } else if (str[0] == '$') {
+            ok = ieee_flconvert_bin(str+1, 4, mant, &exponent);
+        } else {
+            ok = ieee_flconvert(str, mant, &exponent);
+        }
+
+        if (!ok) {
+            type = FL_QNAN;
+        } else if (mant[0] & LIMB_TOP_BIT) {
+            /*
+             * Non-zero.
+             */
+            exponent--;
+            if (exponent >= 2 - expmax && exponent <= expmax) {
+                type = FL_NORMAL;
+            } else if (exponent > 0) {
+                if (pass0 == 1)
+                    error(ERR_WARNING|ERR_WARN_FL_OVERFLOW|ERR_PASS1,
+                          "overflow in floating-point constant");
+                type = FL_INFINITY;
+            } else {
+                /* underflow or denormal; the denormal code handles
+                   actual underflow. */
+                type = FL_DENORMAL;
+            }
+        } else {
+            /* Zero */
+            type = FL_ZERO;
+        }
+    }
+
+    switch (type) {
+    case FL_ZERO:
+    zero:
+        memset(mant, 0, sizeof mant);
+        break;
+
+    case FL_DENORMAL:
+    {
+        shift = -(exponent + expmax - 2 - fmt->exponent)
+            + fmt->explicit;
+        ieee_shr(mant, shift);
+        ieee_round(minus, mant, bits);
+        if (mant[one_pos] & one_mask) {
+            /* One's position is set, we rounded up into normal range */
+            exponent = 1;
+            if (!fmt->explicit)
+                mant[one_pos] &= ~one_mask;     /* remove explicit one */
+            mant[0] |= exponent << (LIMB_BITS-1 - fmt->exponent);
+        } else {
+            if (daz || is_zero(mant)) {
+                /* Flush denormals to zero */
+                error(ERR_WARNING|ERR_WARN_FL_UNDERFLOW|ERR_PASS1,
+                      "underflow in floating-point constant");
+                goto zero;
+            } else {
+                error(ERR_WARNING|ERR_WARN_FL_DENORM|ERR_PASS1,
+                      "denormal floating-point constant");
+            }
+        }
+        break;
+    }
+
+    case FL_NORMAL:
+        exponent += expmax - 1;
+        ieee_shr(mant, fmt->exponent+fmt->explicit);
+        ieee_round(minus, mant, bits);
+        /* did we scale up by one? */
+        if (test_bit(mant, fmt->exponent+fmt->explicit-1)) {
+            ieee_shr(mant, 1);
+            exponent++;
+            if (exponent >= (expmax << 1)-1) {
+                    error(ERR_WARNING|ERR_WARN_FL_OVERFLOW|ERR_PASS1,
+                          "overflow in floating-point constant");
+                type = FL_INFINITY;
+                goto overflow;
+            }
+        }
+
+        if (!fmt->explicit)
+            mant[one_pos] &= ~one_mask; /* remove explicit one */
+        mant[0] |= exponent << (LIMB_BITS-1 - fmt->exponent);
+        break;
+
+    case FL_INFINITY:
+    case FL_QNAN:
+    case FL_SNAN:
+    overflow:
+        memset(mant, 0, sizeof mant);
+        mant[0] = (((fp_limb)1 << fmt->exponent)-1)
+            << (LIMB_BITS-1 - fmt->exponent);
+        if (fmt->explicit)
+            mant[one_pos] |= one_mask;
+        if (type == FL_QNAN)
+            set_bit(mant, fmt->exponent+fmt->explicit+1);
+        else if (type == FL_SNAN)
+            set_bit(mant, fmt->exponent+fmt->explicit+fmt->mantissa);
+        break;
+    }
+
+    mant[0] |= minus ? LIMB_TOP_BIT : 0;
+
+    for (i = fmt->bytes - 1; i >= 0; i--)
+        *result++ = mant[i/LIMB_BYTES] >> (((LIMB_BYTES-1)-(i%LIMB_BYTES))*8);
+
+    return 1;                   /* success */
+}
+
+int float_const(const char *number, int sign, uint8_t *result,
+                int bytes, efunc err)
+{
+    error = err;
+
+    switch (bytes) {
+    case 1:
+        return to_float(number, sign, result, &ieee_8);
+    case 2:
+        return to_float(number, sign, result, &ieee_16);
+    case 4:
+        return to_float(number, sign, result, &ieee_32);
+    case 8:
+        return to_float(number, sign, result, &ieee_64);
+    case 10:
+        return to_float(number, sign, result, &ieee_80);
+    case 16:
+        return to_float(number, sign, result, &ieee_128);
+    default:
+        error(ERR_PANIC, "strange value %d passed to float_const", bytes);
+        return 0;
+    }
+}
+
+/* Set floating-point options */
+int float_option(const char *option)
+{
+    if (!nasm_stricmp(option, "daz")) {
+        daz = true;
+        return 0;
+    } else if (!nasm_stricmp(option, "nodaz")) {
+        daz = false;
+        return 0;
+    } else if (!nasm_stricmp(option, "near")) {
+        rc = FLOAT_RC_NEAR;
+        return 0;
+    } else if (!nasm_stricmp(option, "down")) {
+        rc = FLOAT_RC_DOWN;
+        return 0;
+    } else if (!nasm_stricmp(option, "up")) {
+        rc = FLOAT_RC_UP;
+        return 0;
+    } else if (!nasm_stricmp(option, "zero")) {
+        rc = FLOAT_RC_ZERO;
+        return 0;
+    } else if (!nasm_stricmp(option, "default")) {
+        rc = FLOAT_RC_NEAR;
+        daz = false;
+        return 0;
+    } else {
+        return -1;              /* Unknown option */
+    }
+}