diff options
Diffstat (limited to 'arch/powerpc/math-emu/udivmodti4.c')
| -rw-r--r-- | arch/powerpc/math-emu/udivmodti4.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/arch/powerpc/math-emu/udivmodti4.c b/arch/powerpc/math-emu/udivmodti4.c new file mode 100644 index 000000000..1e52633dc --- /dev/null +++ b/arch/powerpc/math-emu/udivmodti4.c @@ -0,0 +1,192 @@ +// SPDX-License-Identifier: GPL-2.0 +/* This has so very few changes over libgcc2's __udivmoddi4 it isn't funny. */ + +#include <math-emu/soft-fp.h> + +#undef count_leading_zeros +#define count_leading_zeros __FP_CLZ + +void +_fp_udivmodti4(_FP_W_TYPE q[2], _FP_W_TYPE r[2], + _FP_W_TYPE n1, _FP_W_TYPE n0, + _FP_W_TYPE d1, _FP_W_TYPE d0) +{ + _FP_W_TYPE q0, q1, r0, r1; + _FP_I_TYPE b, bm; + + if (d1 == 0) + { +#if !UDIV_NEEDS_NORMALIZATION + if (d0 > n1) + { + /* 0q = nn / 0D */ + + udiv_qrnnd (q0, n0, n1, n0, d0); + q1 = 0; + + /* Remainder in n0. */ + } + else + { + /* qq = NN / 0d */ + + if (d0 == 0) + d0 = 1 / d0; /* Divide intentionally by zero. */ + + udiv_qrnnd (q1, n1, 0, n1, d0); + udiv_qrnnd (q0, n0, n1, n0, d0); + + /* Remainder in n0. */ + } + + r0 = n0; + r1 = 0; + +#else /* UDIV_NEEDS_NORMALIZATION */ + + if (d0 > n1) + { + /* 0q = nn / 0D */ + + count_leading_zeros (bm, d0); + + if (bm != 0) + { + /* Normalize, i.e. make the most significant bit of the + denominator set. */ + + d0 = d0 << bm; + n1 = (n1 << bm) | (n0 >> (_FP_W_TYPE_SIZE - bm)); + n0 = n0 << bm; + } + + udiv_qrnnd (q0, n0, n1, n0, d0); + q1 = 0; + + /* Remainder in n0 >> bm. */ + } + else + { + /* qq = NN / 0d */ + + if (d0 == 0) + d0 = 1 / d0; /* Divide intentionally by zero. */ + + count_leading_zeros (bm, d0); + + if (bm == 0) + { + /* From (n1 >= d0) /\ (the most significant bit of d0 is set), + conclude (the most significant bit of n1 is set) /\ (the + leading quotient digit q1 = 1). + + This special case is necessary, not an optimization. + (Shifts counts of SI_TYPE_SIZE are undefined.) */ + + n1 -= d0; + q1 = 1; + } + else + { + _FP_W_TYPE n2; + + /* Normalize. */ + + b = _FP_W_TYPE_SIZE - bm; + + d0 = d0 << bm; + n2 = n1 >> b; + n1 = (n1 << bm) | (n0 >> b); + n0 = n0 << bm; + + udiv_qrnnd (q1, n1, n2, n1, d0); + } + + /* n1 != d0... */ + + udiv_qrnnd (q0, n0, n1, n0, d0); + + /* Remainder in n0 >> bm. */ + } + + r0 = n0 >> bm; + r1 = 0; +#endif /* UDIV_NEEDS_NORMALIZATION */ + } + else + { + if (d1 > n1) + { + /* 00 = nn / DD */ + + q0 = 0; + q1 = 0; + + /* Remainder in n1n0. */ + r0 = n0; + r1 = n1; + } + else + { + /* 0q = NN / dd */ + + count_leading_zeros (bm, d1); + if (bm == 0) + { + /* From (n1 >= d1) /\ (the most significant bit of d1 is set), + conclude (the most significant bit of n1 is set) /\ (the + quotient digit q0 = 0 or 1). + + This special case is necessary, not an optimization. */ + + /* The condition on the next line takes advantage of that + n1 >= d1 (true due to program flow). */ + if (n1 > d1 || n0 >= d0) + { + q0 = 1; + sub_ddmmss (n1, n0, n1, n0, d1, d0); + } + else + q0 = 0; + + q1 = 0; + + r0 = n0; + r1 = n1; + } + else + { + _FP_W_TYPE m1, m0, n2; + + /* Normalize. */ + + b = _FP_W_TYPE_SIZE - bm; + + d1 = (d1 << bm) | (d0 >> b); + d0 = d0 << bm; + n2 = n1 >> b; + n1 = (n1 << bm) | (n0 >> b); + n0 = n0 << bm; + + udiv_qrnnd (q0, n1, n2, n1, d1); + umul_ppmm (m1, m0, q0, d0); + + if (m1 > n1 || (m1 == n1 && m0 > n0)) + { + q0--; + sub_ddmmss (m1, m0, m1, m0, d1, d0); + } + + q1 = 0; + + /* Remainder in (n1n0 - m1m0) >> bm. */ + sub_ddmmss (n1, n0, n1, n0, m1, m0); + r0 = (n1 << b) | (n0 >> bm); + r1 = n1 >> bm; + } + } + } + + q[0] = q0; q[1] = q1; + r[0] = r0, r[1] = r1; +} |