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1/* Compile with:
2 *
3 * glsl_compiler --version 400 --dump-builder int64.glsl > builtin_int64.h
4 *
5 * Version 4.00+ is required for umulExtended.
6 */
7#version 400
8#extension GL_ARB_gpu_shader_int64: require
9#extension GL_ARB_shading_language_420pack: require
10
11uvec2
12umul64(uvec2 a, uvec2 b)
13{
14   uvec2 result;
15
16   umulExtended(a.x, b.x, result.y, result.x);
17   result.y += a.x * b.y + a.y * b.x;
18
19   return result;
20}
21
22ivec2
23sign64(ivec2 a)
24{
25   ivec2 result;
26
27   result.y = a.y >> 31;
28   result.x = result.y | int((a.x | a.y) != 0);
29
30   return result;
31}
32
33uvec4
34udivmod64(uvec2 n, uvec2 d)
35{
36   uvec2 quot = uvec2(0U, 0U);
37   int log2_denom = findMSB(d.y) + 32;
38
39   /* If the upper 32 bits of denom are non-zero, it is impossible for shifts
40    * greater than 32 bits to occur.  If the upper 32 bits of the numerator
41    * are zero, it is impossible for (denom << [63, 32]) <= numer unless
42    * denom == 0.
43    */
44   if (d.y == 0 && n.y >= d.x) {
45      log2_denom = findMSB(d.x);
46
47      /* Since the upper 32 bits of denom are zero, log2_denom <= 31 and we
48       * don't have to compare log2_denom inside the loop as is done in the
49       * general case (below).
50       */
51      for (int i = 31; i >= 1; i--) {
52	 if (log2_denom <= 31 - i && (d.x << i) <= n.y) {
53	    n.y -= d.x << i;
54	    quot.y |= 1U << i;
55	 }
56      }
57
58      /* log2_denom is always <= 31, so manually peel the last loop
59       * iteration.
60       */
61      if (d.x <= n.y) {
62	 n.y -= d.x;
63	 quot.y |= 1U;
64      }
65   }
66
67   uint64_t d64 = packUint2x32(d);
68   uint64_t n64 = packUint2x32(n);
69   for (int i = 31; i >= 1; i--) {
70      if (log2_denom <= 63 - i && (d64 << i) <= n64) {
71	 n64 -= d64 << i;
72	 quot.x |= 1U << i;
73      }
74   }
75
76   /* log2_denom is always <= 63, so manually peel the last loop
77    * iteration.
78    */
79   if (d64 <= n64) {
80      n64 -= d64;
81      quot.x |= 1U;
82   }
83
84   return uvec4(quot, unpackUint2x32(n64));
85}
86
87uvec2
88udiv64(uvec2 n, uvec2 d)
89{
90   return udivmod64(n, d).xy;
91}
92
93ivec2
94idiv64(ivec2 _n, ivec2 _d)
95{
96   const bool negate = (_n.y < 0) != (_d.y < 0);
97   uvec2 n = unpackUint2x32(uint64_t(abs(packInt2x32(_n))));
98   uvec2 d = unpackUint2x32(uint64_t(abs(packInt2x32(_d))));
99
100   uvec2 quot = udivmod64(n, d).xy;
101
102   return negate ? unpackInt2x32(-int64_t(packUint2x32(quot))) : ivec2(quot);
103}
104
105uvec2
106umod64(uvec2 n, uvec2 d)
107{
108   return udivmod64(n, d).zw;
109}
110
111ivec2
112imod64(ivec2 _n, ivec2 _d)
113{
114   const bool negate = (_n.y < 0) != (_d.y < 0);
115   uvec2 n = unpackUint2x32(uint64_t(abs(packInt2x32(_n))));
116   uvec2 d = unpackUint2x32(uint64_t(abs(packInt2x32(_d))));
117
118   uvec2 rem = udivmod64(n, d).zw;
119
120   return negate ? unpackInt2x32(-int64_t(packUint2x32(rem))) : ivec2(rem);
121}
122