noisymime
/
speeduino
mirror of https://github.com/noisymime/speeduino.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Add option to use libdivide in maths.h functions

This commit is contained in:
Josh Stewart 2021-12-09 10:50:17 +11:00
parent 36d285d883
commit 105534efb8
2 changed files with 37 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
speeduino/maths.h
View File

@ -1,6 +1,8 @@
#ifndef MATH_H
#define MATH_H
#define USE_LIBDIVIDE
int fastMap1023toX(int, int);
unsigned long percentage(byte, unsigned long);
unsigned long halfPercentage(byte, unsigned long);
@ -16,4 +18,6 @@ unsigned long divu100(unsigned long);
//This is a new version that allows for out_min
#define fastMap10Bit(x, out_min, out_max) ( ( ((unsigned long)x * (out_max-out_min)) >> 10 ) + out_min)
#endif

66
speeduino/maths.ino
View File

@ -1,5 +1,14 @@
#include "maths.h"
#include "globals.h"
#include "src/libdivide/libdivide.h"
#ifdef USE_LIBDIVIDE
//Constants used for libdivide
struct libdivide::libdivide_u32_t libdiv_u32_10 = libdivide::libdivide_u32_gen(10);
struct libdivide::libdivide_u32_t libdiv_u32_100 = libdivide::libdivide_u32_gen(100);
struct libdivide::libdivide_s32_t libdiv_s32_100 = libdivide::libdivide_s32_gen(100);
struct libdivide::libdivide_u32_t libdiv_u32_200 = libdivide::libdivide_u32_gen(200);
#endif
//Replace the standard arduino map() function to use the div function instead
int fastMap(unsigned long x, int in_min, int in_max, int out_min, int out_max)
@ -13,65 +22,56 @@ int fastMap(unsigned long x, int in_min, int in_max, int out_min, int out_max)
//return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}
/*
The following are all fast versions of specific divisions
Ref: www.hackersdelight.org/divcMore.pdf
*/
//Unsigned divide by 10
unsigned int divu10(unsigned int n)
{
unsigned long q, r;
q = (n >> 1) + (n >> 2);
q = q + (q >> 4);
q = q + (q >> 8);
q = q + (q >> 16);
q = q >> 3;
r = n - (q * 10);
return q + ((r + 6) >> 4);
#ifdef USE_LIBDIVIDE
return libdivide::libdivide_u32_do(n, &libdiv_u32_10);
#else
return (n / 10);
#endif
}
//Signed divide by 100
int divs100(long n)
{
#ifdef USE_LIBDIVIDE
return libdivide::libdivide_s32_do(n, &libdiv_s32_100);
#else
return (n / 100); // Amazingly, gcc is producing a better /divide by 100 function than this
/*
long q, r;
n = n + (n>>31 & 99);
q = (n >> 1) + (n >> 3) + (n >> 6) - (n >> 10) +
(n >> 12) + (n >> 13) - (n >> 16);
q = q + (q >> 20);
q = q >> 6;
r = n - q*100;
return q + ((r + 28) >> 7);
*/
#endif
}
//Unsigned divide by 100
unsigned long divu100(unsigned long n)
{
//return (n / 100);
unsigned long q, r;
q = (n >> 1) + (n >> 3) + (n >> 6) - (n >> 10) +
(n >> 12) + (n >> 13) - (n >> 16);
q = q + (q >> 20);
q = q >> 6;
r = n - (q * 100);
return q + ((r + 28) >> 7);
#ifdef USE_LIBDIVIDE
return libdivide::libdivide_u32_do(n, &libdiv_u32_100);
#else
return (n / 100);
#endif
}
//Return x percent of y
//This is a relatively fast approximation of a percentage value.
unsigned long percentage(byte x, unsigned long y)
{
return (y * x) / 100; //For some reason this is faster
//return divu100(y * x);
#ifdef USE_LIBDIVIDE
return libdivide::libdivide_u32_do((y * x), &libdiv_u32_100);
#else
return (y * x) / 100;
#endif
}
//Same as above, but 0.5% accuracy
unsigned long halfPercentage(byte x, unsigned long y)
{
#ifdef USE_LIBDIVIDE
return libdivide::libdivide_u32_do((y * x), &libdiv_u32_200);
#else
return (y * x) / 200;
#endif
}
/*