| //===-- udivmodti4.c - Implement __udivmodti4 -----------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements __udivmodti4 for the compiler_rt library. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #if __x86_64 |
| |
| #include "int_lib.h" |
| |
| // Effects: if rem != 0, *rem = a % b |
| // Returns: a / b |
| |
| // Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide |
| |
| tu_int |
| __udivmodti4(tu_int a, tu_int b, tu_int* rem) |
| { |
| const unsigned n_udword_bits = sizeof(du_int) * CHAR_BIT; |
| const unsigned n_utword_bits = sizeof(tu_int) * CHAR_BIT; |
| utwords n; |
| n.all = a; |
| utwords d; |
| d.all = b; |
| utwords q; |
| utwords r; |
| unsigned sr; |
| // special cases, X is unknown, K != 0 |
| if (n.high == 0) |
| { |
| if (d.high == 0) |
| { |
| // 0 X |
| // --- |
| // 0 X |
| if (rem) |
| *rem = n.low % d.low; |
| return n.low / d.low; |
| } |
| // 0 X |
| // --- |
| // K X |
| if (rem) |
| *rem = n.low; |
| return 0; |
| } |
| // n.high != 0 |
| if (d.low == 0) |
| { |
| if (d.high == 0) |
| { |
| // K X |
| // --- |
| // 0 0 |
| if (rem) |
| *rem = n.high % d.low; |
| return n.high / d.low; |
| } |
| // d.high != 0 |
| if (n.low == 0) |
| { |
| // K 0 |
| // --- |
| // K 0 |
| if (rem) |
| { |
| r.high = n.high % d.high; |
| r.low = 0; |
| *rem = r.all; |
| } |
| return n.high / d.high; |
| } |
| // K K |
| // --- |
| // K 0 |
| if ((d.high & (d.high - 1)) == 0) // if d is a power of 2 |
| { |
| if (rem) |
| { |
| r.low = n.low; |
| r.high = n.high & (d.high - 1); |
| *rem = r.all; |
| } |
| return n.high >> __builtin_ctzll(d.high); |
| } |
| // K K |
| // --- |
| // K 0 |
| sr = __builtin_clzll(d.high) - __builtin_clzll(n.high); |
| // 0 <= sr <= n_udword_bits - 2 or sr large |
| if (sr > n_udword_bits - 2) |
| { |
| if (rem) |
| *rem = n.all; |
| return 0; |
| } |
| ++sr; |
| // 1 <= sr <= n_udword_bits - 1 |
| // q.all = n.all << (n_utword_bits - sr); |
| q.low = 0; |
| q.high = n.low << (n_udword_bits - sr); |
| // r.all = n.all >> sr; |
| r.high = n.high >> sr; |
| r.low = (n.high << (n_udword_bits - sr)) | (n.low >> sr); |
| } |
| else // d.low != 0 |
| { |
| if (d.high == 0) |
| { |
| // K X |
| // --- |
| // 0 K |
| if ((d.low & (d.low - 1)) == 0) // if d is a power of 2 |
| { |
| if (rem) |
| *rem = n.low & (d.low - 1); |
| if (d.low == 1) |
| return n.all; |
| unsigned sr = __builtin_ctzll(d.low); |
| q.high = n.high >> sr; |
| q.low = (n.high << (n_udword_bits - sr)) | (n.low >> sr); |
| return q.all; |
| } |
| // K X |
| // --- |
| // 0 K |
| sr = 1 + n_udword_bits + __builtin_clzll(d.low) |
| - __builtin_clzll(n.high); |
| // 2 <= sr <= n_utword_bits - 1 |
| // q.all = n.all << (n_utword_bits - sr); |
| // r.all = n.all >> sr; |
| // if (sr == n_udword_bits) |
| // { |
| // q.low = 0; |
| // q.high = n.low; |
| // r.high = 0; |
| // r.low = n.high; |
| // } |
| // else if (sr < n_udword_bits) // 2 <= sr <= n_udword_bits - 1 |
| // { |
| // q.low = 0; |
| // q.high = n.low << (n_udword_bits - sr); |
| // r.high = n.high >> sr; |
| // r.low = (n.high << (n_udword_bits - sr)) | (n.low >> sr); |
| // } |
| // else // n_udword_bits + 1 <= sr <= n_utword_bits - 1 |
| // { |
| // q.low = n.low << (n_utword_bits - sr); |
| // q.high = (n.high << (n_utword_bits - sr)) | |
| // (n.low >> (sr - n_udword_bits)); |
| // r.high = 0; |
| // r.low = n.high >> (sr - n_udword_bits); |
| // } |
| q.low = (n.low << (n_utword_bits - sr)) & |
| ((di_int)(int)(n_udword_bits - sr) >> (n_udword_bits-1)); |
| q.high = ((n.low << ( n_udword_bits - sr)) & |
| ((di_int)(int)(sr - n_udword_bits - 1) >> (n_udword_bits-1))) | |
| (((n.high << (n_utword_bits - sr)) | |
| (n.low >> (sr - n_udword_bits))) & |
| ((di_int)(int)(n_udword_bits - sr) >> (n_udword_bits-1))); |
| r.high = (n.high >> sr) & |
| ((di_int)(int)(sr - n_udword_bits) >> (n_udword_bits-1)); |
| r.low = ((n.high >> (sr - n_udword_bits)) & |
| ((di_int)(int)(n_udword_bits - sr - 1) >> (n_udword_bits-1))) | |
| (((n.high << (n_udword_bits - sr)) | |
| (n.low >> sr)) & |
| ((di_int)(int)(sr - n_udword_bits) >> (n_udword_bits-1))); |
| } |
| else |
| { |
| // K X |
| // --- |
| // K K |
| sr = __builtin_clzll(d.high) - __builtin_clzll(n.high); |
| // 0 <= sr <= n_udword_bits - 1 or sr large |
| if (sr > n_udword_bits - 1) |
| { |
| if (rem) |
| *rem = n.all; |
| return 0; |
| } |
| ++sr; |
| // 1 <= sr <= n_udword_bits |
| // q.all = n.all << (n_utword_bits - sr); |
| q.low = 0; |
| q.high = n.low << (n_udword_bits - sr); |
| // r.all = n.all >> sr; |
| // if (sr < n_udword_bits) |
| // { |
| // r.high = n.high >> sr; |
| // r.low = (n.high << (n_udword_bits - sr)) | (n.low >> sr); |
| // } |
| // else |
| // { |
| // r.high = 0; |
| // r.low = n.high; |
| // } |
| r.high = (n.high >> sr) & |
| ((di_int)(int)(sr - n_udword_bits) >> (n_udword_bits-1)); |
| r.low = (n.high << (n_udword_bits - sr)) | |
| ((n.low >> sr) & |
| ((di_int)(int)(sr - n_udword_bits) >> (n_udword_bits-1))); |
| } |
| } |
| // Not a special case |
| // q and r are initialized with: |
| // q.all = n.all << (n_utword_bits - sr); |
| // r.all = n.all >> sr; |
| // 1 <= sr <= n_utword_bits - 1 |
| su_int carry = 0; |
| for (; sr > 0; --sr) |
| { |
| // r:q = ((r:q) << 1) | carry |
| r.high = (r.high << 1) | (r.low >> (n_udword_bits - 1)); |
| r.low = (r.low << 1) | (q.high >> (n_udword_bits - 1)); |
| q.high = (q.high << 1) | (q.low >> (n_udword_bits - 1)); |
| q.low = (q.low << 1) | carry; |
| // carry = 0; |
| // if (r.all >= d.all) |
| // { |
| // r.all -= d.all; |
| // carry = 1; |
| // } |
| const ti_int s = (ti_int)(d.all - r.all - 1) >> (n_utword_bits - 1); |
| carry = s & 1; |
| r.all -= d.all & s; |
| } |
| q.all = (q.all << 1) | carry; |
| if (rem) |
| *rem = r.all; |
| return q.all; |
| } |
| |
| #endif |