Revision 1586
Implementation of exponential. Not tested, don't even know if it works at all.
trunk/code/projects/fp_math/fp_math.c  

10  10  
11  11 
#define TABLE_LENGTH 64 
12  12 
#define TABLE_STEP 1621//.160757 
13 
#define EXP_MAGICONSTANT 

13  14  
14 
static inline int32_t trig_lookup(int32_t theta, int32_t* table); 

15  
16  15 
static int32_t linspace[TABLE_LENGTH] PROGMEM = { 
17  16 
0, 1621, 3242, 4863, 6485, 8106, 9727, 11348, 
18  17 
12969, 14590, 16212, 17833, 19454, 21075, 22696, 24317, 
...  ...  
44  43 
return fp_cos(theta + FP_PI_OVER_TWO); 
45  44 
} 
46  45  
46 
int32_t fp_exp(int32_t x) { 

47 
//Try with partial fractions for now. 

48 
int32_t xsquare = fp_mult(x,x); 

49 
int32_t result, i; 

50 


51 
if(theta > EXP_MAGICONSTANT) { 

52 
usb_puts("Output value is out of range.\n\r"); 

53 
return 1; 

54 
} 

55 


56 
//This is again, massive amounts of lazyness. 

57 
//The approximation fails outside this range (approximately). 

58 
if(theta < 17) 

59 
return 0; 

60 


61 
result = xsquare; 

62 
for(i= (22 << 16); i > (2 << 16); i= (4 << 16)) { 

63 
result += i; 

64 
result = fp_div(xsquare, result); 

65 
} 

66 


67 
result += (2 << 16)  x; 

68 
return (1 << 16) + fp_div(fp_mult((2 << 16), x), result); 

69  
70 
} 

71  
47  72 
//Quadratic interpolation. 
48  73 
int32_t fp_cos(int32_t theta) { 
49  74 
uint8_t n; 
...  ...  
69  94 
n++; 
70  95 

71  96 
//theta is between x_{n} and x_{n+1} 
72 


73  97 
if(n == TABLE_LENGTH  1) { 
74  98 
//Perform linear interpolation, since we're close to zero anyway. 
75  99 
x_n = pgm_read_dword(&linspace[TABLE_LENGTH  1]); 
trunk/code/projects/fp_math/fp_math.h  

3  3 
#define _FP_MATH_H_ 
4  4  
5  5 
#define FP_PI 205887 
6 
#define FP_E 178145 

6  7  
7  8 
#include <stdint.h> 
8  9 
Also available in: Unified diff