path: root/xen/common/lib.c

#include <xen/ctype.h>
#include <xen/lib.h>
#include <xen/types.h>
#include <xen/init.h>
#include <asm/byteorder.h>

/* for ctype.h */
const unsigned char _ctype[] = {
    _C,_C,_C,_C,_C,_C,_C,_C,                        /* 0-7 */
    _C,_C|_S,_C|_S,_C|_S,_C|_S,_C|_S,_C,_C,         /* 8-15 */
    _C,_C,_C,_C,_C,_C,_C,_C,                        /* 16-23 */
    _C,_C,_C,_C,_C,_C,_C,_C,                        /* 24-31 */
    _S|_SP,_P,_P,_P,_P,_P,_P,_P,                    /* 32-39 */
    _P,_P,_P,_P,_P,_P,_P,_P,                        /* 40-47 */
    _D,_D,_D,_D,_D,_D,_D,_D,                        /* 48-55 */
    _D,_D,_P,_P,_P,_P,_P,_P,                        /* 56-63 */
    _P,_U|_X,_U|_X,_U|_X,_U|_X,_U|_X,_U|_X,_U,      /* 64-71 */
    _U,_U,_U,_U,_U,_U,_U,_U,                        /* 72-79 */
    _U,_U,_U,_U,_U,_U,_U,_U,                        /* 80-87 */
    _U,_U,_U,_P,_P,_P,_P,_P,                        /* 88-95 */
    _P,_L|_X,_L|_X,_L|_X,_L|_X,_L|_X,_L|_X,_L,      /* 96-103 */
    _L,_L,_L,_L,_L,_L,_L,_L,                        /* 104-111 */
    _L,_L,_L,_L,_L,_L,_L,_L,                        /* 112-119 */
    _L,_L,_L,_P,_P,_P,_P,_C,                        /* 120-127 */
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,                /* 128-143 */
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,                /* 144-159 */
    _S|_SP,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,   /* 160-175 */
    _P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,       /* 176-191 */
    _U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,       /* 192-207 */
    _U,_U,_U,_U,_U,_U,_U,_P,_U,_U,_U,_U,_U,_U,_U,_L,       /* 208-223 */
    _L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,       /* 224-239 */
    _L,_L,_L,_L,_L,_L,_L,_P,_L,_L,_L,_L,_L,_L,_L,_L};      /* 240-255 */

/*
 * A couple of 64 bit operations ported from FreeBSD.
 * The code within the '#if BITS_PER_LONG == 32' block below, and no other
 * code in this file, is distributed under the following licensing terms
 * This is the modified '3-clause' BSD license with the obnoxious
 * advertising clause removed, as permitted by University of California.
 *
 * Copyright (c) 1992, 1993
 * The Regents of the University of California.  All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */
#if BITS_PER_LONG == 32

/*
 * Depending on the desired operation, we view a `long long' (aka quad_t) in
 * one or more of the following formats.
 */
union uu {
    s64            q;              /* as a (signed) quad */
    s64            uq;             /* as an unsigned quad */
    long           sl[2];          /* as two signed longs */
    unsigned long  ul[2];          /* as two unsigned longs */
};

#ifdef __BIG_ENDIAN
#define _QUAD_HIGHWORD 0
#define _QUAD_LOWWORD 1
#else /* __LITTLE_ENDIAN */
#define _QUAD_HIGHWORD 1
#define _QUAD_LOWWORD 0
#endif

/*
 * Define high and low longwords.
 */
#define H               _QUAD_HIGHWORD
#define L               _QUAD_LOWWORD

/*
 * Total number of bits in a quad_t and in the pieces that make it up.
 * These are used for shifting, and also below for halfword extraction
 * and assembly.
 */
#define CHAR_BIT        8               /* number of bits in a char */
#define QUAD_BITS       (sizeof(s64) * CHAR_BIT)
#define LONG_BITS       (sizeof(long) * CHAR_BIT)
#define HALF_BITS       (sizeof(long) * CHAR_BIT / 2)

/*
 * Extract high and low shortwords from longword, and move low shortword of
 * longword to upper half of long, i.e., produce the upper longword of
 * ((quad_t)(x) << (number_of_bits_in_long/2)).  (`x' must actually be u_long.)
 *
 * These are used in the multiply code, to split a longword into upper
 * and lower halves, and to reassemble a product as a quad_t, shifted left
 * (sizeof(long)*CHAR_BIT/2).
 */
#define HHALF(x)        ((x) >> HALF_BITS)
#define LHALF(x)        ((x) & ((1 << HALF_BITS) - 1))
#define LHUP(x)         ((x) << HALF_BITS)

/*
 * Multiprecision divide.  This algorithm is from Knuth vol. 2 (2nd ed),
 * section 4.3.1, pp. 257--259.
 */
#define B (1 << HALF_BITS) /* digit base */

/* Combine two `digits' to make a single two-digit number. */
#define COMBINE(a, b) (((u_long)(a) << HALF_BITS) | (b))

/* select a type for digits in base B */
typedef u_long digit;

/*
 * Shift p[0]..p[len] left `sh' bits, ignoring any bits that
 * `fall out' the left (there never will be any such anyway).
 * We may assume len >= 0.  NOTE THAT THIS WRITES len+1 DIGITS.
 */
static void shl(register digit *p, register int len, register int sh)
{
    register int i;

    for (i = 0; i < len; i++)
        p[i] = LHALF(p[i] << sh) | (p[i + 1] >> (HALF_BITS - sh));
    p[i] = LHALF(p[i] << sh);
}

/*
 * __qdivrem(u, v, rem) returns u/v and, optionally, sets *rem to u%v.
 *
 * We do this in base 2-sup-HALF_BITS, so that all intermediate products
 * fit within u_long.  As a consequence, the maximum length dividend and
 * divisor are 4 `digits' in this base (they are shorter if they have
 * leading zeros).
 */
u64 __qdivrem(u64 uq, u64 vq, u64 *arq)
{
    union uu tmp;
    digit *u, *v, *q;
    register digit v1, v2;
    u_long qhat, rhat, t;
    int m, n, d, j, i;
    digit uspace[5], vspace[5], qspace[5];

    /*
     * Take care of special cases: divide by zero, and u < v.
     */
    if (vq == 0) {
        /* divide by zero. */
        static volatile const unsigned int zero = 0;

        tmp.ul[H] = tmp.ul[L] = 1 / zero;
        if (arq)
            *arq = uq;
        return (tmp.q);
    }
    if (uq < vq) {
        if (arq)
            *arq = uq;
        return (0);
    }
    u = &uspace[0];
    v = &vspace[0];
    q = &qspace[0];

    /*
     * Break dividend and divisor into digits in base B, then
     * count leading zeros to determine m and n.  When done, we
     * will have:
     * u = (u[1]u[2]...u[m+n]) sub B
     * v = (v[1]v[2]...v[n]) sub B
     * v[1] != 0
     * 1 < n <= 4 (if n = 1, we use a different division algorithm)
     * m >= 0 (otherwise u < v, which we already checked)
     * m + n = 4
     * and thus
     * m = 4 - n <= 2
     */
    tmp.uq = uq;
    u[0] = 0;
    u[1] = HHALF(tmp.ul[H]);
    u[2] = LHALF(tmp.ul[H]);
    u[3] = HHALF(tmp.ul[L]);
    u[4] = LHALF(tmp.ul[L]);
    tmp.uq = vq;
    v[1] = HHALF(tmp.ul[H]);
    v[2] = LHALF(tmp.ul[H]);
    v[3] = HHALF(tmp.ul[L]);
    v[4] = LHALF(tmp.ul[L]);
    for (n = 4; v[1] == 0; v++) {
        if (--n == 1) {
            u_long rbj; /* r*B+u[j] (not root boy jim) */
            digit q1, q2, q3, q4;

            /*
             * Change of plan, per exercise 16.
             * r = 0;
             * for j = 1..4:
             *  q[j] = floor((r*B + u[j]) / v),
             *  r = (r*B + u[j]) % v;
             * We unroll this completely here.
             */
            t = v[2]; /* nonzero, by definition */
            q1 = u[1] / t;
            rbj = COMBINE(u[1] % t, u[2]);
            q2 = rbj / t;
            rbj = COMBINE(rbj % t, u[3]);
            q3 = rbj / t;
            rbj = COMBINE(rbj % t, u[4]);
            q4 = rbj / t;
            if (arq)
                *arq = rbj % t;
            tmp.ul[H] = COMBINE(q1, q2);
            tmp.ul[L] = COMBINE(q3, q4);
            return (tmp.q);
        }
    }

    /*
     * By adjusting q once we determine m, we can guarantee that
     * there is a complete four-digit quotient at &qspace[1] when
     * we finally stop.
     */
    for (m = 4 - n; u[1] == 0; u++)
        m--;
    for (i = 4 - m; --i >= 0;)
        q[i] = 0;
    q += 4 - m;

    /*
     * Here we run Program D, translated from MIX to C and acquiring
     * a few minor changes.
     *
     * D1: choose multiplier 1 << d to ensure v[1] >= B/2.
     */
    d = 0;
    for (t = v[1]; t < B / 2; t <<= 1)
        d++;
    if (d > 0) {
        shl(&u[0], m + n, d);  /* u <<= d */
        shl(&v[1], n - 1, d);  /* v <<= d */
    }
    /*
     * D2: j = 0.
     */
    j = 0;
    v1 = v[1]; /* for D3 -- note that v[1..n] are constant */
    v2 = v[2]; /* for D3 */
    do {
        register digit uj0, uj1, uj2;

        /*
         * D3: Calculate qhat (\^q, in TeX notation).
         * Let qhat = min((u[j]*B + u[j+1])/v[1], B-1), and
         * let rhat = (u[j]*B + u[j+1]) mod v[1].
         * While rhat < B and v[2]*qhat > rhat*B+u[j+2],
         * decrement qhat and increase rhat correspondingly.
         * Note that if rhat >= B, v[2]*qhat < rhat*B.
         */
        uj0 = u[j + 0]; /* for D3 only -- note that u[j+...] change */
        uj1 = u[j + 1]; /* for D3 only */
        uj2 = u[j + 2]; /* for D3 only */
        if (uj0 == v1) {
            qhat = B;
            rhat = uj1;
            goto qhat_too_big;
        } else {
            u_long nn = COMBINE(uj0, uj1);
            qhat = nn / v1;
            rhat = nn % v1;
        }
        while (v2 * qhat > COMBINE(rhat, uj2)) {
        qhat_too_big:
            qhat--;
            if ((rhat += v1) >= B)
                break;
        }
        /*
         * D4: Multiply and subtract.
         * The variable `t' holds any borrows across the loop.
         * We split this up so that we do not require v[0] = 0,
         * and to eliminate a final special case.
         */
        for (t = 0, i = n; i > 0; i--) {
            t = u[i + j] - v[i] * qhat - t;
            u[i + j] = LHALF(t);
            t = (B - HHALF(t)) & (B - 1);
        }
        t = u[j] - t;
        u[j] = LHALF(t);
        /*
         * D5: test remainder.
         * There is a borrow if and only if HHALF(t) is nonzero;
         * in that (rare) case, qhat was too large (by exactly 1).
         * Fix it by adding v[1..n] to u[j..j+n].
         */
        if (HHALF(t)) {
            qhat--;
            for (t = 0, i = n; i > 0; i--) { /* D6: add back. */
                t += u[i + j] + v[i];
                u[i + j] = LHALF(t);
                t = HHALF(t);
            }
            u[j] = LHALF(u[j] + t);
        }
        q[j] = qhat;
    } while (++j <= m);  /* D7: loop on j. */

    /*
     * If caller wants the remainder, we have to calculate it as
     * u[m..m+n] >> d (this is at most n digits and thus fits in
     * u[m+1..m+n], but we may need more source digits).
     */
    if (arq) {
        if (d) {
            for (i = m + n; i > m; --i)
                u[i] = (u[i] >> d) |
                    LHALF(u[i - 1] << (HALF_BITS - d));
            u[i] = 0;
        }
        tmp.ul[H] = COMBINE(uspace[1], uspace[2]);
        tmp.ul[L] = COMBINE(uspace[3], uspace[4]);
        *arq = tmp.q;
    }

    tmp.ul[H] = COMBINE(qspace[1], qspace[2]);
    tmp.ul[L] = COMBINE(qspace[3], qspace[4]);
    return (tmp.q);
}

/*
 * Divide two signed quads.
 * Truncates towards zero, as required by C99.
 */
s64 __divdi3(s64 a, s64 b)
{
    u64 ua, ub, uq;
    int neg = (a < 0) ^ (b < 0);
    ua = (a < 0) ? -(u64)a : a;
    ub = (b < 0) ? -(u64)b : b;
    uq = __qdivrem(ua, ub, (u64 *)0);
    return (neg ? -uq : uq);
}


/*
 * Divide two unsigned quads.
 */
u64 __udivdi3(u64 a, u64 b)
{
    return __qdivrem(a, b, (u64 *)0);
}

/*
 * Remainder of unsigned quad division
 */
u64 __umoddi3(u64 a, u64 b)
{
    u64 rem;
    __qdivrem(a, b, &rem);
    return rem;
}

/*
 * Remainder of signed quad division.
 * Truncates towards zero, as required by C99:
 *  11 %  5 =  1
 * -11 %  5 = -1
 *  11 % -5 =  1
 * -11 % -5 =  1
 */
s64 __moddi3(s64 a, s64 b)
{
    u64 ua, ub, urem;
    int neg = (a < 0);
    ua = neg ? -(u64)a : a;
    ub = (b < 0) ? -(u64)b : b;
    __qdivrem(ua, ub, &urem);
    return (neg ? -urem : urem);
}

/*
 * Quotient and remainder of unsigned long long division
 */
s64 __ldivmod_helper(s64 a, s64 b, s64 *r)
{
    u64 ua, ub, rem, quot;

    ua = ABS(a);
    ub = ABS(b);
    quot = __qdivrem(ua, ub, &rem);
    if ( a < 0 )
        *r = -rem;
    else
        *r = rem;
    if ( (a < 0) ^ (b < 0) )
        return -quot;
    else
        return quot;
}
#endif /* BITS_PER_LONG == 32 */

/* Compute with 96 bit intermediate result: (a*b)/c */
uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
{
#ifdef CONFIG_X86
    asm ( "mul %%rdx; div %%rcx" : "=a" (a) : "0" (a), "d" (b), "c" (c) );
    return a;
#else
    union {
        uint64_t ll;
        struct {
#ifdef WORDS_BIGENDIAN
            uint32_t high, low;
#else
            uint32_t low, high;
#endif            
        } l;
    } u, res;
    uint64_t rl, rh;

    u.ll = a;
    rl = (uint64_t)u.l.low * (uint64_t)b;
    rh = (uint64_t)u.l.high * (uint64_t)b;
    rh += (rl >> 32);
    res.l.high = rh / c;
    res.l.low = (((rh % c) << 32) + (rl & 0xffffffff)) / c;
    return res.ll;
#endif
}

unsigned long long parse_size_and_unit(const char *s, const char **ps)
{
    unsigned long long ret;
    const char *s1;

    ret = simple_strtoull(s, &s1, 0);

    switch ( *s1 )
    {
    case 'G': case 'g':
        ret <<= 10;
    case 'M': case 'm':
        ret <<= 10;
    case 'K': case 'k':
        ret <<= 10;
    case 'B': case 'b':
        s1++;
        break;
    default:
        ret <<= 10; /* default to kB */
        break;
    }

    if ( ps != NULL )
        *ps = s1;

    return ret;
}

typedef void (*ctor_func_t)(void);
extern const ctor_func_t __ctors_start[], __ctors_end[];

void __init init_constructors(void)
{
    const ctor_func_t *f;
    for ( f = __ctors_start; f < __ctors_end; ++f )
        (*f)();
}

/*
 * Local variables:
 * mode: C
 * c-file-style: "BSD"
 * c-basic-offset: 4
 * tab-width: 4
 * indent-tabs-mode: nil
 * End:
 */