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poly.h
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1 /*---------------------------------------------------------------------------+
2  | poly.h |
3  | |
4  | Header file for the FPU-emu poly*.c source files. |
5  | |
6  | Copyright (C) 1994,1999 |
7  | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
8  | Australia. E-mail [email protected] |
9  | |
10  | Declarations and definitions for functions operating on Xsig (12-byte |
11  | extended-significand) quantities. |
12  | |
13  +---------------------------------------------------------------------------*/
14 
15 #ifndef _POLY_H
16 #define _POLY_H
17 
18 /* This 12-byte structure is used to improve the accuracy of computation
19  of transcendental functions.
20  Intended to be used to get results better than 8-byte computation
21  allows. 9-byte would probably be sufficient.
22  */
23 typedef struct {
24  unsigned long lsw;
25  unsigned long midw;
26  unsigned long msw;
27 } Xsig;
28 
29 asmlinkage void mul64(unsigned long long const *a, unsigned long long const *b,
30  unsigned long long *result);
31 asmlinkage void polynomial_Xsig(Xsig *, const unsigned long long *x,
32  const unsigned long long terms[], const int n);
33 
34 asmlinkage void mul32_Xsig(Xsig *, const unsigned long mult);
35 asmlinkage void mul64_Xsig(Xsig *, const unsigned long long *mult);
36 asmlinkage void mul_Xsig_Xsig(Xsig *dest, const Xsig *mult);
37 
38 asmlinkage void shr_Xsig(Xsig *, const int n);
41 asmlinkage void div_Xsig(Xsig *x1, const Xsig *x2, const Xsig *dest);
42 
43 /* Macro to extract the most significant 32 bits from a long long */
44 #define LL_MSW(x) (((unsigned long *)&x)[1])
45 
46 /* Macro to initialize an Xsig struct */
47 #define MK_XSIG(a,b,c) { c, b, a }
48 
49 /* Macro to access the 8 ms bytes of an Xsig as a long long */
50 #define XSIG_LL(x) (*(unsigned long long *)&x.midw)
51 
52 /*
53  Need to run gcc with optimizations on to get these to
54  actually be in-line.
55  */
56 
57 /* Multiply two fixed-point 32 bit numbers, producing a 32 bit result.
58  The answer is the ms word of the product. */
59 /* Some versions of gcc make it difficult to stop eax from being clobbered.
60  Merely specifying that it is used doesn't work...
61  */
62 static inline unsigned long mul_32_32(const unsigned long arg1,
63  const unsigned long arg2)
64 {
65  int retval;
66  asm volatile ("mull %2; movl %%edx,%%eax":"=a" (retval)
67  :"0"(arg1), "g"(arg2)
68  :"dx");
69  return retval;
70 }
71 
72 /* Add the 12 byte Xsig x2 to Xsig dest, with no checks for overflow. */
73 static inline void add_Xsig_Xsig(Xsig *dest, const Xsig *x2)
74 {
75  asm volatile ("movl %1,%%edi; movl %2,%%esi;\n"
76  "movl (%%esi),%%eax; addl %%eax,(%%edi);\n"
77  "movl 4(%%esi),%%eax; adcl %%eax,4(%%edi);\n"
78  "movl 8(%%esi),%%eax; adcl %%eax,8(%%edi);\n":"=g"
79  (*dest):"g"(dest), "g"(x2)
80  :"ax", "si", "di");
81 }
82 
83 /* Add the 12 byte Xsig x2 to Xsig dest, adjust exp if overflow occurs. */
84 /* Note: the constraints in the asm statement didn't always work properly
85  with gcc 2.5.8. Changing from using edi to using ecx got around the
86  problem, but keep fingers crossed! */
87 static inline void add_two_Xsig(Xsig *dest, const Xsig *x2, long int *exp)
88 {
89  asm volatile ("movl %2,%%ecx; movl %3,%%esi;\n"
90  "movl (%%esi),%%eax; addl %%eax,(%%ecx);\n"
91  "movl 4(%%esi),%%eax; adcl %%eax,4(%%ecx);\n"
92  "movl 8(%%esi),%%eax; adcl %%eax,8(%%ecx);\n"
93  "jnc 0f;\n"
94  "rcrl 8(%%ecx); rcrl 4(%%ecx); rcrl (%%ecx)\n"
95  "movl %4,%%ecx; incl (%%ecx)\n"
96  "movl $1,%%eax; jmp 1f;\n"
97  "0: xorl %%eax,%%eax;\n" "1:\n":"=g" (*exp), "=g"(*dest)
98  :"g"(dest), "g"(x2), "g"(exp)
99  :"cx", "si", "ax");
100 }
101 
102 /* Negate (subtract from 1.0) the 12 byte Xsig */
103 /* This is faster in a loop on my 386 than using the "neg" instruction. */
104 static inline void negate_Xsig(Xsig *x)
105 {
106  asm volatile ("movl %1,%%esi;\n"
107  "xorl %%ecx,%%ecx;\n"
108  "movl %%ecx,%%eax; subl (%%esi),%%eax; movl %%eax,(%%esi);\n"
109  "movl %%ecx,%%eax; sbbl 4(%%esi),%%eax; movl %%eax,4(%%esi);\n"
110  "movl %%ecx,%%eax; sbbl 8(%%esi),%%eax; movl %%eax,8(%%esi);\n":"=g"
111  (*x):"g"(x):"si", "ax", "cx");
112 }
113 
114 #endif /* _POLY_H */