41 lines
780 B
C
41 lines
780 B
C
/*
|
|
* Tiny FPU enable module.
|
|
*
|
|
* Part of the ToAruOS Kernel
|
|
* (C) 2011 Kevin Lange ...
|
|
* To whatever possible level this short of a code chunk
|
|
* can be considered copyrightable in your jurisdiction.
|
|
*/
|
|
#include <system.h>
|
|
|
|
/**
|
|
* Set the FPU control word
|
|
*
|
|
* @param cw What to set the control word to.
|
|
*/
|
|
void
|
|
set_fpu_cw(const uint16_t cw) {
|
|
asm volatile("fldcw %0" :: "m"(cw));
|
|
}
|
|
|
|
/**
|
|
* Enable the FPU
|
|
*
|
|
* We are assuming that we have one to begin with, but since we
|
|
* only really operate on 686 machines, we do, so we're not
|
|
* going to bother checking.
|
|
*/
|
|
void
|
|
enable_fpu() {
|
|
size_t cr4;
|
|
asm volatile ("mov %%cr4, %0" : "=r"(cr4));
|
|
cr4 |= 0x200;
|
|
asm volatile ("mov %0, %%cr4" :: "r"(cr4));
|
|
set_fpu_cw(0x37F);
|
|
}
|
|
|
|
/*
|
|
* vim:tabstop=4
|
|
* vim:noexpandtab
|
|
*/
|