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kernel/linux-imx6_3.14.28/arch/x86/math-emu/poly.h 4.55 KB
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  /*---------------------------------------------------------------------------+
   |  poly.h                                                                   |
   |                                                                           |
   |  Header file for the FPU-emu poly*.c source files.                        |
   |                                                                           |
   | Copyright (C) 1994,1999                                                   |
   |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   |                       Australia.  E-mail   billm@melbpc.org.au            |
   |                                                                           |
   | Declarations and definitions for functions operating on Xsig (12-byte     |
   | extended-significand) quantities.                                         |
   |                                                                           |
   +---------------------------------------------------------------------------*/
  
  #ifndef _POLY_H
  #define _POLY_H
  
  /* This 12-byte structure is used to improve the accuracy of computation
     of transcendental functions.
     Intended to be used to get results better than 8-byte computation
     allows. 9-byte would probably be sufficient.
     */
  typedef struct {
  	unsigned long lsw;
  	unsigned long midw;
  	unsigned long msw;
  } Xsig;
  
  asmlinkage void mul64(unsigned long long const *a, unsigned long long const *b,
  		      unsigned long long *result);
  asmlinkage void polynomial_Xsig(Xsig *, const unsigned long long *x,
  				const unsigned long long terms[], const int n);
  
  asmlinkage void mul32_Xsig(Xsig *, const unsigned long mult);
  asmlinkage void mul64_Xsig(Xsig *, const unsigned long long *mult);
  asmlinkage void mul_Xsig_Xsig(Xsig *dest, const Xsig *mult);
  
  asmlinkage void shr_Xsig(Xsig *, const int n);
  asmlinkage int round_Xsig(Xsig *);
  asmlinkage int norm_Xsig(Xsig *);
  asmlinkage void div_Xsig(Xsig *x1, const Xsig *x2, const Xsig *dest);
  
  /* Macro to extract the most significant 32 bits from a long long */
  #define LL_MSW(x)     (((unsigned long *)&x)[1])
  
  /* Macro to initialize an Xsig struct */
  #define MK_XSIG(a,b,c)     { c, b, a }
  
  /* Macro to access the 8 ms bytes of an Xsig as a long long */
  #define XSIG_LL(x)         (*(unsigned long long *)&x.midw)
  
  /*
     Need to run gcc with optimizations on to get these to
     actually be in-line.
     */
  
  /* Multiply two fixed-point 32 bit numbers, producing a 32 bit result.
     The answer is the ms word of the product. */
  /* Some versions of gcc make it difficult to stop eax from being clobbered.
     Merely specifying that it is used doesn't work...
   */
  static inline unsigned long mul_32_32(const unsigned long arg1,
  				      const unsigned long arg2)
  {
  	int retval;
  	asm volatile ("mull %2; movl %%edx,%%eax":"=a" (retval)
  		      :"0"(arg1), "g"(arg2)
  		      :"dx");
  	return retval;
  }
  
  /* Add the 12 byte Xsig x2 to Xsig dest, with no checks for overflow. */
  static inline void add_Xsig_Xsig(Xsig *dest, const Xsig *x2)
  {
  	asm volatile ("movl %1,%%edi; movl %2,%%esi;
  "
  		      "movl (%%esi),%%eax; addl %%eax,(%%edi);
  "
  		      "movl 4(%%esi),%%eax; adcl %%eax,4(%%edi);
  "
  		      "movl 8(%%esi),%%eax; adcl %%eax,8(%%edi);
  ":"=g"
  		      (*dest):"g"(dest), "g"(x2)
  		      :"ax", "si", "di");
  }
  
  /* Add the 12 byte Xsig x2 to Xsig dest, adjust exp if overflow occurs. */
  /* Note: the constraints in the asm statement didn't always work properly
     with gcc 2.5.8.  Changing from using edi to using ecx got around the
     problem, but keep fingers crossed! */
  static inline void add_two_Xsig(Xsig *dest, const Xsig *x2, long int *exp)
  {
  	asm volatile ("movl %2,%%ecx; movl %3,%%esi;
  "
  		      "movl (%%esi),%%eax; addl %%eax,(%%ecx);
  "
  		      "movl 4(%%esi),%%eax; adcl %%eax,4(%%ecx);
  "
  		      "movl 8(%%esi),%%eax; adcl %%eax,8(%%ecx);
  "
  		      "jnc 0f;
  "
  		      "rcrl 8(%%ecx); rcrl 4(%%ecx); rcrl (%%ecx)
  "
  		      "movl %4,%%ecx; incl (%%ecx)
  "
  		      "movl $1,%%eax; jmp 1f;
  "
  		      "0: xorl %%eax,%%eax;
  " "1:
  ":"=g" (*exp), "=g"(*dest)
  		      :"g"(dest), "g"(x2), "g"(exp)
  		      :"cx", "si", "ax");
  }
  
  /* Negate (subtract from 1.0) the 12 byte Xsig */
  /* This is faster in a loop on my 386 than using the "neg" instruction. */
  static inline void negate_Xsig(Xsig *x)
  {
  	asm volatile ("movl %1,%%esi;
  "
  		      "xorl %%ecx,%%ecx;
  "
  		      "movl %%ecx,%%eax; subl (%%esi),%%eax; movl %%eax,(%%esi);
  "
  		      "movl %%ecx,%%eax; sbbl 4(%%esi),%%eax; movl %%eax,4(%%esi);
  "
  		      "movl %%ecx,%%eax; sbbl 8(%%esi),%%eax; movl %%eax,8(%%esi);
  ":"=g"
  		      (*x):"g"(x):"si", "ax", "cx");
  }
  
  #endif /* _POLY_H */