michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "prlong.h"
michael@0: 
michael@0: static PRInt64 ll_zero = LL_INIT( 0x00000000,0x00000000 );
michael@0: static PRInt64 ll_maxint = LL_INIT( 0x7fffffff, 0xffffffff );
michael@0: static PRInt64 ll_minint = LL_INIT( 0x80000000, 0x00000000 );
michael@0: static PRUint64 ll_maxuint = LL_INIT( 0xffffffff, 0xffffffff );
michael@0: 
michael@0: PR_IMPLEMENT(PRInt64) LL_Zero(void) { return ll_zero; }
michael@0: PR_IMPLEMENT(PRInt64) LL_MaxInt(void) { return ll_maxint; }
michael@0: PR_IMPLEMENT(PRInt64) LL_MinInt(void) { return ll_minint; }
michael@0: PR_IMPLEMENT(PRUint64) LL_MaxUint(void) { return ll_maxuint; }
michael@0: 
michael@0: #ifndef HAVE_LONG_LONG
michael@0: /*
michael@0: ** Divide 64-bit a by 32-bit b, which must be normalized so its high bit is 1.
michael@0: */
michael@0: static void norm_udivmod32(PRUint32 *qp, PRUint32 *rp, PRUint64 a, PRUint32 b)
michael@0: {
michael@0:     PRUint32 d1, d0, q1, q0;
michael@0:     PRUint32 r1, r0, m;
michael@0: 
michael@0:     d1 = _hi16(b);
michael@0:     d0 = _lo16(b);
michael@0:     r1 = a.hi % d1;
michael@0:     q1 = a.hi / d1;
michael@0:     m = q1 * d0;
michael@0:     r1 = (r1 << 16) | _hi16(a.lo);
michael@0:     if (r1 < m) {
michael@0:         q1--, r1 += b;
michael@0:         if (r1 >= b	/* i.e., we didn't get a carry when adding to r1 */
michael@0: 	    && r1 < m) {
michael@0: 	    q1--, r1 += b;
michael@0: 	}
michael@0:     }
michael@0:     r1 -= m;
michael@0:     r0 = r1 % d1;
michael@0:     q0 = r1 / d1;
michael@0:     m = q0 * d0;
michael@0:     r0 = (r0 << 16) | _lo16(a.lo);
michael@0:     if (r0 < m) {
michael@0:         q0--, r0 += b;
michael@0:         if (r0 >= b
michael@0: 	    && r0 < m) {
michael@0: 	    q0--, r0 += b;
michael@0: 	}
michael@0:     }
michael@0:     *qp = (q1 << 16) | q0;
michael@0:     *rp = r0 - m;
michael@0: }
michael@0: 
michael@0: static PRUint32 CountLeadingZeros(PRUint32 a)
michael@0: {
michael@0:     PRUint32 t;
michael@0:     PRUint32 r = 32;
michael@0: 
michael@0:     if ((t = a >> 16) != 0)
michael@0: 	r -= 16, a = t;
michael@0:     if ((t = a >> 8) != 0)
michael@0: 	r -= 8, a = t;
michael@0:     if ((t = a >> 4) != 0)
michael@0: 	r -= 4, a = t;
michael@0:     if ((t = a >> 2) != 0)
michael@0: 	r -= 2, a = t;
michael@0:     if ((t = a >> 1) != 0)
michael@0: 	r -= 1, a = t;
michael@0:     if (a & 1)
michael@0: 	r--;
michael@0:     return r;
michael@0: }
michael@0: 
michael@0: PR_IMPLEMENT(void) ll_udivmod(PRUint64 *qp, PRUint64 *rp, PRUint64 a, PRUint64 b)
michael@0: {
michael@0:     PRUint32 n0, n1, n2;
michael@0:     PRUint32 q0, q1;
michael@0:     PRUint32 rsh, lsh;
michael@0: 
michael@0:     n0 = a.lo;
michael@0:     n1 = a.hi;
michael@0: 
michael@0:     if (b.hi == 0) {
michael@0: 	if (b.lo > n1) {
michael@0: 	    /* (0 q0) = (n1 n0) / (0 D0) */
michael@0: 
michael@0: 	    lsh = CountLeadingZeros(b.lo);
michael@0: 
michael@0: 	    if (lsh) {
michael@0: 		/*
michael@0: 		 * Normalize, i.e. make the most significant bit of the
michael@0: 		 * denominator be set.
michael@0: 		 */
michael@0: 		b.lo = b.lo << lsh;
michael@0: 		n1 = (n1 << lsh) | (n0 >> (32 - lsh));
michael@0: 		n0 = n0 << lsh;
michael@0: 	    }
michael@0: 
michael@0: 	    a.lo = n0, a.hi = n1;
michael@0: 	    norm_udivmod32(&q0, &n0, a, b.lo);
michael@0: 	    q1 = 0;
michael@0: 
michael@0: 	    /* remainder is in n0 >> lsh */
michael@0: 	} else {
michael@0: 	    /* (q1 q0) = (n1 n0) / (0 d0) */
michael@0: 
michael@0: 	    if (b.lo == 0)		/* user wants to divide by zero! */
michael@0: 		b.lo = 1 / b.lo;	/* so go ahead and crash */
michael@0: 
michael@0: 	    lsh = CountLeadingZeros(b.lo);
michael@0: 
michael@0: 	    if (lsh == 0) {
michael@0: 		/*
michael@0: 		 * From (n1 >= b.lo)
michael@0: 		 *   && (the most significant bit of b.lo is set),
michael@0: 		 * conclude that
michael@0: 		 *	(the most significant bit of n1 is set)
michael@0: 		 *   && (the leading quotient digit q1 = 1).
michael@0: 		 *
michael@0: 		 * This special case is necessary, not an optimization
michael@0: 		 * (Shifts counts of 32 are undefined).
michael@0: 		 */
michael@0: 		n1 -= b.lo;
michael@0: 		q1 = 1;
michael@0: 	    } else {
michael@0: 		/*
michael@0: 		 * Normalize.
michael@0: 		 */
michael@0: 		rsh = 32 - lsh;
michael@0: 
michael@0: 		b.lo = b.lo << lsh;
michael@0: 		n2 = n1 >> rsh;
michael@0: 		n1 = (n1 << lsh) | (n0 >> rsh);
michael@0: 		n0 = n0 << lsh;
michael@0: 
michael@0: 		a.lo = n1, a.hi = n2;
michael@0: 		norm_udivmod32(&q1, &n1, a, b.lo);
michael@0: 	    }
michael@0: 
michael@0: 	    /* n1 != b.lo... */
michael@0: 
michael@0: 	    a.lo = n0, a.hi = n1;
michael@0: 	    norm_udivmod32(&q0, &n0, a, b.lo);
michael@0: 
michael@0: 	    /* remainder in n0 >> lsh */
michael@0: 	}
michael@0: 
michael@0: 	if (rp) {
michael@0: 	    rp->lo = n0 >> lsh;
michael@0: 	    rp->hi = 0;
michael@0: 	}
michael@0:     } else {
michael@0: 	if (b.hi > n1) {
michael@0: 	    /* (0 0) = (n1 n0) / (D1 d0) */
michael@0: 
michael@0: 	    q0 = 0;
michael@0: 	    q1 = 0;
michael@0: 
michael@0: 	    /* remainder in (n1 n0) */
michael@0: 	    if (rp) {
michael@0: 		rp->lo = n0;
michael@0: 		rp->hi = n1;
michael@0: 	    }
michael@0: 	} else {
michael@0: 	    /* (0 q0) = (n1 n0) / (d1 d0) */
michael@0: 
michael@0: 	    lsh = CountLeadingZeros(b.hi);
michael@0: 	    if (lsh == 0) {
michael@0: 		/*
michael@0: 		 * From (n1 >= b.hi)
michael@0: 		 *   && (the most significant bit of b.hi is set),
michael@0: 		 * conclude that
michael@0: 		 *      (the most significant bit of n1 is set)
michael@0: 		 *   && (the quotient digit q0 = 0 or 1).
michael@0: 		 *
michael@0: 		 * This special case is necessary, not an optimization.
michael@0: 		 */
michael@0: 
michael@0: 		/*
michael@0: 		 * The condition on the next line takes advantage of that
michael@0: 		 * n1 >= b.hi (true due to control flow).
michael@0: 		 */
michael@0: 		if (n1 > b.hi || n0 >= b.lo) {
michael@0: 		    q0 = 1;
michael@0: 		    a.lo = n0, a.hi = n1;
michael@0: 		    LL_SUB(a, a, b);
michael@0: 		} else {
michael@0: 		    q0 = 0;
michael@0: 		}
michael@0: 		q1 = 0;
michael@0: 
michael@0: 		if (rp) {
michael@0: 		    rp->lo = n0;
michael@0: 		    rp->hi = n1;
michael@0: 		}
michael@0: 	    } else {
michael@0: 		PRInt64 m;
michael@0: 
michael@0: 		/*
michael@0: 		 * Normalize.
michael@0: 		 */
michael@0: 		rsh = 32 - lsh;
michael@0: 
michael@0: 		b.hi = (b.hi << lsh) | (b.lo >> rsh);
michael@0: 		b.lo = b.lo << lsh;
michael@0: 		n2 = n1 >> rsh;
michael@0: 		n1 = (n1 << lsh) | (n0 >> rsh);
michael@0: 		n0 = n0 << lsh;
michael@0: 
michael@0: 		a.lo = n1, a.hi = n2;
michael@0: 		norm_udivmod32(&q0, &n1, a, b.hi);
michael@0: 		LL_MUL32(m, q0, b.lo);
michael@0: 
michael@0: 		if ((m.hi > n1) || ((m.hi == n1) && (m.lo > n0))) {
michael@0: 		    q0--;
michael@0: 		    LL_SUB(m, m, b);
michael@0: 		}
michael@0: 
michael@0: 		q1 = 0;
michael@0: 
michael@0: 		/* Remainder is ((n1 n0) - (m1 m0)) >> lsh */
michael@0: 		if (rp) {
michael@0: 		    a.lo = n0, a.hi = n1;
michael@0: 		    LL_SUB(a, a, m);
michael@0: 		    rp->lo = (a.hi << rsh) | (a.lo >> lsh);
michael@0: 		    rp->hi = a.hi >> lsh;
michael@0: 		}
michael@0: 	    }
michael@0: 	}
michael@0:     }
michael@0: 
michael@0:     if (qp) {
michael@0: 	qp->lo = q0;
michael@0: 	qp->hi = q1;
michael@0:     }
michael@0: }
michael@0: #endif /* !HAVE_LONG_LONG */