--- /dev/null
+#define clz(a) (sizeof(a) == 8 ? __builtin_clzll(a) : __builtin_clz(a))
+
+// Adapted from Figure 3-40 of The PowerPC Compiler Writer's Guide
+static __inline fixuint_t __udivXi3(fixuint_t n, fixuint_t d) {
+ const unsigned N = sizeof(fixuint_t) * CHAR_BIT;
+ // d == 0 cases are unspecified.
+ unsigned sr = (d ? clz(d) : N) - (n ? clz(n) : N);
+ // 0 <= sr <= N - 1 or sr is very large.
+ if (sr > N - 1) // n < d
+ return 0;
+ if (sr == N - 1) // d == 1
+ return n;
+ ++sr;
+ // 1 <= sr <= N - 1. Shifts do not trigger UB.
+ fixuint_t r = n >> sr;
+ n <<= N - sr;
+ fixuint_t carry = 0;
+ for (; sr > 0; --sr) {
+ r = (r << 1) | (n >> (N - 1));
+ n = (n << 1) | carry;
+ // Branch-less version of:
+ // carry = 0;
+ // if (r >= d) r -= d, carry = 1;
+ const fixint_t s = (fixint_t)(d - r - 1) >> (N - 1);
+ carry = s & 1;
+ r -= d & s;
+ }
+ n = (n << 1) | carry;
+ return n;
+}
+
+// Mostly identical to __udivXi3 but the return values are different.
+static __inline fixuint_t __umodXi3(fixuint_t n, fixuint_t d) {
+ const unsigned N = sizeof(fixuint_t) * CHAR_BIT;
+ // d == 0 cases are unspecified.
+ unsigned sr = (d ? clz(d) : N) - (n ? clz(n) : N);
+ // 0 <= sr <= N - 1 or sr is very large.
+ if (sr > N - 1) // n < d
+ return n;
+ if (sr == N - 1) // d == 1
+ return 0;
+ ++sr;
+ // 1 <= sr <= N - 1. Shifts do not trigger UB.
+ fixuint_t r = n >> sr;
+ n <<= N - sr;
+ fixuint_t carry = 0;
+ for (; sr > 0; --sr) {
+ r = (r << 1) | (n >> (N - 1));
+ n = (n << 1) | carry;
+ // Branch-less version of:
+ // carry = 0;
+ // if (r >= d) r -= d, carry = 1;
+ const fixint_t s = (fixint_t)(d - r - 1) >> (N - 1);
+ carry = s & 1;
+ r -= d & s;
+ }
+ return r;
+}
#include "int_lib.h"
+typedef du_int fixuint_t;
+typedef di_int fixint_t;
+#include "int_div_impl.inc"
+
// Returns: a / b
COMPILER_RT_ABI du_int __udivdi3(du_int a, du_int b) {
- return __udivmoddi4(a, b, 0);
+ return __udivXi3(a, b);
}
#include "int_lib.h"
-// Returns: a / b
+typedef su_int fixuint_t;
+typedef si_int fixint_t;
+#include "int_div_impl.inc"
-// Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide
+// Returns: a / b
-// This function should not call __divsi3!
-COMPILER_RT_ABI su_int __udivsi3(su_int n, su_int d) {
- const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT;
- su_int q;
- su_int r;
- unsigned sr;
- // special cases
- if (d == 0)
- return 0; // ?!
- if (n == 0)
- return 0;
- sr = __builtin_clz(d) - __builtin_clz(n);
- // 0 <= sr <= n_uword_bits - 1 or sr large
- if (sr > n_uword_bits - 1) // d > r
- return 0;
- if (sr == n_uword_bits - 1) // d == 1
- return n;
- ++sr;
- // 1 <= sr <= n_uword_bits - 1
- // Not a special case
- q = n << (n_uword_bits - sr);
- r = n >> sr;
- su_int carry = 0;
- for (; sr > 0; --sr) {
- // r:q = ((r:q) << 1) | carry
- r = (r << 1) | (q >> (n_uword_bits - 1));
- q = (q << 1) | carry;
- // carry = 0;
- // if (r.all >= d.all)
- // {
- // r.all -= d.all;
- // carry = 1;
- // }
- const si_int s = (si_int)(d - r - 1) >> (n_uword_bits - 1);
- carry = s & 1;
- r -= d & s;
- }
- q = (q << 1) | carry;
- return q;
+COMPILER_RT_ABI su_int __udivsi3(su_int a, su_int b) {
+ return __udivXi3(a, b);
}
#if defined(__ARM_EABI__)
#include "int_lib.h"
+typedef du_int fixuint_t;
+typedef di_int fixint_t;
+#include "int_div_impl.inc"
+
// Returns: a % b
COMPILER_RT_ABI du_int __umoddi3(du_int a, du_int b) {
- du_int r;
- __udivmoddi4(a, b, &r);
- return r;
+ return __umodXi3(a, b);
}
#include "int_lib.h"
+typedef su_int fixuint_t;
+typedef si_int fixint_t;
+#include "int_div_impl.inc"
+
// Returns: a % b
COMPILER_RT_ABI su_int __umodsi3(su_int a, su_int b) {
- return a - __udivsi3(a, b) * b;
+ return __umodXi3(a, b);
}