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Questions - x87

Assembly language initialization of floating-point unit

Just out of curiosity I'm fiddling around with some demoscene 256 byte intros. I came around one production which ran fine under MS-DOS 6.22 but crashes under FreeDOS 1.3 - "sometimes". It t...
test-img

Codor

assembly

dos

x86-16

tasm

x87

Votes: 0

Answers: 0

what's this decompiled f2xm1/fscale sequence meant to do?

I am trying to reverse engineer some decomiled code which originally had been written in C/C++, i.e. I suspect that the below FPU related code sequence is probably derived from some simple C-code &quo...
test-img

wothke

assembly

x86

fpu

x87

Votes: 0

Answers: 2

Latest Answer

Without the complete context it is difficult to be entirely sure, but the computation here seems to be a naive computation of exp(x) via F2XM1. Note that the argument to F2XM1 was restricted to [-0.5,...
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njuffa

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