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/* Compile with:
*
* glsl_compiler --version 140 --dump-builder int64.glsl > builtin_int64.h
*
* Using version 1.40+ prevents built-in variables from being included.
*/
#version 400
#extension GL_ARB_gpu_shader_int64: require
#extension GL_ARB_shading_language_420pack: require
uvec2
umul64(uvec2 a, uvec2 b)
{
uvec2 result;
umulExtended(a.x, b.x, result.y, result.x);
result.y += a.x * b.y + a.y * b.x;
return result;
}
ivec2
sign64(ivec2 a)
{
ivec2 result;
result.y = a.y >> 31;
result.x = result.y | int((a.x | a.y) != 0);
return result;
}
uvec4
udivmod64(uvec2 n, uvec2 d)
{
uvec2 quot = uvec2(0U, 0U);
int log2_denom = findMSB(d.y) + 32;
/* If the upper 32 bits of denom are non-zero, it is impossible for shifts
* greater than 32 bits to occur. If the upper 32 bits of the numerator
* are zero, it is impossible for (denom << [63, 32]) <= numer unless
* denom == 0.
*/
if (d.y == 0 && n.y >= d.x) {
log2_denom = findMSB(d.x);
/* Since the upper 32 bits of denom are zero, log2_denom <= 31 and we
* don't have to compare log2_denom inside the loop as is done in the
* general case (below).
*/
for (int i = 31; i >= 1; i--) {
if (log2_denom <= 31 - i && (d.x << i) <= n.y) {
n.y -= d.x << i;
quot.y |= 1U << i;
}
}
/* log2_denom is always <= 31, so manually peel the last loop
* iteration.
*/
if (d.x <= n.y) {
n.y -= d.x;
quot.y |= 1U;
}
}
uint64_t d64 = packUint2x32(d);
uint64_t n64 = packUint2x32(n);
for (int i = 31; i >= 1; i--) {
if (log2_denom <= 63 - i && (d64 << i) <= n64) {
n64 -= d64 << i;
quot.x |= 1U << i;
}
}
/* log2_denom is always <= 63, so manually peel the last loop
* iteration.
*/
if (d64 <= n64) {
n64 -= d64;
quot.x |= 1U;
}
return uvec4(quot, unpackUint2x32(n64));
}
uvec2
udiv64(uvec2 n, uvec2 d)
{
return udivmod64(n, d).xy;
}
ivec2
idiv64(ivec2 _n, ivec2 _d)
{
const bool negate = (_n.y < 0) != (_d.y < 0);
uvec2 n = unpackUint2x32(uint64_t(abs(packInt2x32(_n))));
uvec2 d = unpackUint2x32(uint64_t(abs(packInt2x32(_d))));
uvec2 quot = udivmod64(n, d).xy;
return negate ? unpackInt2x32(-int64_t(packUint2x32(quot))) : ivec2(quot);
}
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