81 lines
1.6 KiB
C
81 lines
1.6 KiB
C
/*
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* x86_has_fpu.c
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*
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* Test for an x86 FPU, and do any necessary setup.
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*/
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#if __SIZEOF_POINTER__ == 4
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#include <i386/x86_init_fpu.c>
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#elif __SIZEOF_POINTER__ == 8
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#include <x86_64/x86_init_fpu.c>
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#else
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#error "Unable to build for to-be-defined architecture type"
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#endif
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#if 0
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#include <inttypes.h>
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#include <sys/fpu.h>
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static inline uint64_t get_cr0(void)
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{
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#if __SIZEOF_POINTER__ == 4
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uint32_t v;
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asm("movl %%cr0,%0":"=r"(v));
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#elif __SIZEOF_POINTER__ == 8
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uint64_t v;
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asm("movq %%cr0,%0":"=r"(v));
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#else
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#error "Unable to build for to-be-defined architecture type"
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#endif
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return v;
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}
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static inline void set_cr0(uint32_t v)
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{
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#if __SIZEOF_POINTER__ == 4
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asm volatile ("movl %0,%%cr0"::"r" (v));
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#elif __SIZEOF_POINTER__ == 8
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asm volatile ("movq %0,%%cr0"::"r" ((uint64_t)v));
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#else
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#error "Unable to build for to-be-defined architecture type"
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#endif
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}
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#define CR0_PE 0x00000001
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#define CR0_MP 0x00000002
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#define CR0_EM 0x00000004
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#define CR0_TS 0x00000008
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#define CR0_ET 0x00000010
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#define CR0_NE 0x00000020
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#define CR0_WP 0x00010000
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#define CR0_AM 0x00040000
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#define CR0_NW 0x20000000
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#define CR0_CD 0x40000000
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#define CR0_PG 0x80000000
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int x86_init_fpu(void)
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{
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uint32_t cr0;
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uint16_t fsw = 0xffff;
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uint16_t fcw = 0xffff;
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cr0 = get_cr0();
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cr0 &= ~(CR0_EM | CR0_TS);
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cr0 |= CR0_MP;
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set_cr0(cr0);
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asm volatile ("fninit");
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asm volatile ("fnstsw %0":"+m" (fsw));
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if (fsw != 0)
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return -1;
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asm volatile ("fnstcw %0":"+m" (fcw));
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if ((fcw & 0x103f) != 0x3f)
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return -1;
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/* Techically, this could be a 386 with a 287. We could add a check
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for that here... */
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return 0;
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}
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#endif
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