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Last change
on this file since 297 was
167,
checked in by mulligan, 11 years ago
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Fast inverse square root C code, emulator mostly does fine running it
(a small bug found, to be fixed next week).
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File size:
317 bytes
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| 1 | #include "stdio.h" |
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| 2 | |
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| 3 | float inv_sqrt(float x) |
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| 4 | { |
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| 5 | union { |
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| 6 | float f; |
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| 7 | int i; |
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| 8 | } tmp; |
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| 9 | tmp.f = x; |
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| 10 | tmp.i = 0x5f3759df - (tmp.i >> 1); |
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| 11 | float y = tmp.f; |
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| 12 | return y * (1.5f - 0.5f * x * y * y); |
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| 13 | } |
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| 14 | |
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| 15 | int main() |
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| 16 | { |
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| 17 | float f; |
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| 18 | int i; |
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| 19 | f = inv_sqrt(16); |
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| 20 | i = (int)(1.0f / f); |
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| 21 | if(i == 4) |
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| 22 | return 5; |
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| 23 | else |
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| 24 | return 7; |
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| 25 | } |
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