193 строки
3.4 KiB
C
193 строки
3.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* This has so very few changes over libgcc2's __udivmoddi4 it isn't funny. */
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#include <math-emu/soft-fp.h>
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#undef count_leading_zeros
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#define count_leading_zeros __FP_CLZ
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void
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_fp_udivmodti4(_FP_W_TYPE q[2], _FP_W_TYPE r[2],
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_FP_W_TYPE n1, _FP_W_TYPE n0,
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_FP_W_TYPE d1, _FP_W_TYPE d0)
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{
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_FP_W_TYPE q0, q1, r0, r1;
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_FP_I_TYPE b, bm;
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if (d1 == 0)
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{
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#if !UDIV_NEEDS_NORMALIZATION
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if (d0 > n1)
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{
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/* 0q = nn / 0D */
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udiv_qrnnd (q0, n0, n1, n0, d0);
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q1 = 0;
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/* Remainder in n0. */
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}
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else
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{
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/* qq = NN / 0d */
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if (d0 == 0)
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d0 = 1 / d0; /* Divide intentionally by zero. */
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udiv_qrnnd (q1, n1, 0, n1, d0);
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udiv_qrnnd (q0, n0, n1, n0, d0);
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/* Remainder in n0. */
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}
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r0 = n0;
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r1 = 0;
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#else /* UDIV_NEEDS_NORMALIZATION */
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if (d0 > n1)
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{
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/* 0q = nn / 0D */
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count_leading_zeros (bm, d0);
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if (bm != 0)
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{
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/* Normalize, i.e. make the most significant bit of the
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denominator set. */
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d0 = d0 << bm;
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n1 = (n1 << bm) | (n0 >> (_FP_W_TYPE_SIZE - bm));
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n0 = n0 << bm;
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}
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udiv_qrnnd (q0, n0, n1, n0, d0);
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q1 = 0;
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/* Remainder in n0 >> bm. */
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}
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else
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{
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/* qq = NN / 0d */
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if (d0 == 0)
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d0 = 1 / d0; /* Divide intentionally by zero. */
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count_leading_zeros (bm, d0);
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if (bm == 0)
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{
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/* From (n1 >= d0) /\ (the most significant bit of d0 is set),
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conclude (the most significant bit of n1 is set) /\ (the
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leading quotient digit q1 = 1).
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This special case is necessary, not an optimization.
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(Shifts counts of SI_TYPE_SIZE are undefined.) */
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n1 -= d0;
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q1 = 1;
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}
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else
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{
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_FP_W_TYPE n2;
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/* Normalize. */
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b = _FP_W_TYPE_SIZE - bm;
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d0 = d0 << bm;
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n2 = n1 >> b;
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n1 = (n1 << bm) | (n0 >> b);
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n0 = n0 << bm;
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udiv_qrnnd (q1, n1, n2, n1, d0);
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}
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/* n1 != d0... */
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udiv_qrnnd (q0, n0, n1, n0, d0);
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/* Remainder in n0 >> bm. */
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}
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r0 = n0 >> bm;
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r1 = 0;
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#endif /* UDIV_NEEDS_NORMALIZATION */
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}
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else
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{
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if (d1 > n1)
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{
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/* 00 = nn / DD */
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q0 = 0;
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q1 = 0;
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/* Remainder in n1n0. */
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r0 = n0;
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r1 = n1;
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}
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else
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{
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/* 0q = NN / dd */
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count_leading_zeros (bm, d1);
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if (bm == 0)
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{
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/* From (n1 >= d1) /\ (the most significant bit of d1 is set),
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conclude (the most significant bit of n1 is set) /\ (the
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quotient digit q0 = 0 or 1).
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This special case is necessary, not an optimization. */
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/* The condition on the next line takes advantage of that
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n1 >= d1 (true due to program flow). */
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if (n1 > d1 || n0 >= d0)
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{
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q0 = 1;
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sub_ddmmss (n1, n0, n1, n0, d1, d0);
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}
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else
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q0 = 0;
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q1 = 0;
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r0 = n0;
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r1 = n1;
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}
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else
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{
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_FP_W_TYPE m1, m0, n2;
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/* Normalize. */
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b = _FP_W_TYPE_SIZE - bm;
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d1 = (d1 << bm) | (d0 >> b);
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d0 = d0 << bm;
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n2 = n1 >> b;
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n1 = (n1 << bm) | (n0 >> b);
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n0 = n0 << bm;
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udiv_qrnnd (q0, n1, n2, n1, d1);
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umul_ppmm (m1, m0, q0, d0);
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if (m1 > n1 || (m1 == n1 && m0 > n0))
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{
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q0--;
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sub_ddmmss (m1, m0, m1, m0, d1, d0);
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}
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q1 = 0;
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/* Remainder in (n1n0 - m1m0) >> bm. */
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sub_ddmmss (n1, n0, n1, n0, m1, m0);
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r0 = (n1 << b) | (n0 >> bm);
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r1 = n1 >> bm;
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}
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}
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}
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q[0] = q0; q[1] = q1;
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r[0] = r0, r[1] = r1;
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}
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