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Atari demoscene BBS
| Re: 32 bit muls |
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Posted by: PeyloW
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May,18.2014-17:55
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Ok, wo what I did with the 16.16 fixed point math multiplication is to simply define it as:
fix16_t fix16_mul(fix16_t a, fix16_t a) { return int32_mul(a >> 8, b >> 8); }
This adds the cost of two shifts, and the mil can then be done with my in regs only multiplication. As far as I see I do not loose any precision, but the rounding is wrong. But who cares :).
The division is a bit trickier:
fix16_t fix16_div(fix16_t a, fix16_t a) { return int32_div(a, b >> 8) << 8; }
Works, and still only two shifts costlier than the normal 32bit divs. But 8 bits of precision is always lost... which is bad :(.
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[All messages in this thread] [Start new thread]
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Topic
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Posted by
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Date
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32 bit muls
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PeyloW
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May,15.2014-22:51
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Re: 32 bit muls
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ggn
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May,17.2014-07:58
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Re: 32 bit muls
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ggn
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May,17.2014-08:00
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Re: 32 bit muls
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PeyloW
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May,17.2014-15:05
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Re: 32 bit muls
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PeyloW
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May,18.2014-17:55
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Re: 32 bit muls
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bob_er/mec
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May,17.2014-09:57
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Re: 32 bit muls
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Alien / ST-CNX
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May,21.2014-21:14
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Re: 32 bit muls
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PeyloW
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May,22.2014-10:52
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Re: 32 bit muls
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PeyloW
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May,23.2014-10:10
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Re: 32 bit muls
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dml
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May,23.2014-22:29
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What's the anti-troll code?
That's your personal code to be able to add comments and messages on the dhs.nu site.
Don't have a code or forgot it? Fix it here.
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