ajout explications transformation float en fixed

This commit is contained in:
hugogogo
2022-02-14 03:08:13 +01:00
parent 8bfe663683
commit 2fcc6782c4
5 changed files with 344 additions and 243 deletions

308
d02/README.md Normal file
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---------------------------------------------------------
DECIMALE VS BINARY
---------------------------------------------------------
11010101
```
1*10000000 | (128) | 2^7 | 128 *1 | 0 *2 +1
1*1000000 | (64) | 2^6 | + 64 *1 | 1 *2 +1
0*100000 | (32) | 2^5 | | 11 *2
1*10000 | (16) | 2^4 | + 16 *1 | 110 *2 +1
0*1000 | (8) | 2^3 | | 1101 *2
1*100 | (4) | 2^2 | + 4 *1 | 11010 *2 +1
0*10 | (2) | 2^1 | | 110101 *2
1*1 | (1) | 2^0 | + 1 *1 | 1101010 *2 +1
| ______ |
| 213 |
```
213
```
2*100 |(1100100)| 10^2 | 1100100 *2 | 0 *10 +2
1*10 | (1010)| 10^1 | + 1010 *1 | 2 *10 +1
3*1 | (1)| 10^0 | + 1 *3 | 21 *10 +3
| | | ___________ | 213
| | | 11010101 |
|
|
1100100 11001000 1 11010010 |
* 2 + 1010 * 3 + 11 |
_________ _________ ___ _________ |
11001000 11010010 11 11010101 |
```
213 -> 11010101
```
213 -128 = 85 | 213 /2 = 106 r 1
85 - 64 = 2 | 106 /2 = 53 r 0
| 53 /2 = 26 r 1
21 - 16 = 5 | 26 /2 = 13 r 0
| 13 /2 = 6 r 1
5 - 4 = 1 | 6 /2 = 3 r 0
| 3 /2 = 1 r 1
1 - 1 = 0 | 1 /2 = 0 r 1
```
11010101 -> 213
```
| 0*2 + 1 = 1
| 1*2 + 1 = 3
| 3*2 = 6
| 6*2 + 1 = 13
| 13*2 = 26
| 26*2 + 1 = 53
| 53*2 = 106
| 106*2 + 1 = 213
```
---------------------------------------------------------
NEGATIVS INTEGERS
---------------------------------------------------------
5 0101 0 0000 0 0000 0000 0000 0000 0000 0000 0000 0000
1010 + 1 1 0001 1 0000 0000 0000 0000 0000 0000 0000 0001
-5 1011 2 0010 2 0000 0000 0000 0000 0000 0000 0000 0010
3 0011 3 0000 0000 0000 0000 0000 0000 0000 0011
4 0100 4 0000 0000 0000 0000 0000 0000 0000 0100
-> 5 0101 5 0000 0000 0000 0000 0000 0000 0000 0101
6 0110 6 0000 0000 0000 0000 0000 0000 0000 0110
7 0111 7 0000 0000 0000 0000 0000 0000 0000 0111
...
0111 1111 1111 1111 1111 1111 1111 1111 MAXINT
1000 0000 0000 0000 0000 0000 0000 0000 MININT
...
8 1000 -8 1111 1111 1111 1111 1111 1111 1111 1000
9 1001 -7 1111 1111 1111 1111 1111 1111 1111 1001
10 1010 -6 1111 1111 1111 1111 1111 1111 1111 1010
-> 11 1011 -5 1111 1111 1111 1111 1111 1111 1111 1011
12 1100 -4 1111 1111 1111 1111 1111 1111 1111 1100
13 1101 -3 1111 1111 1111 1111 1111 1111 1111 1101
14 1110 -2 1111 1111 1111 1111 1111 1111 1111 1110
15 1111 -1 1111 1111 1111 1111 1111 1111 1111 1111
---------------------------------------------------------
FLOATS
---------------------------------------------------------
https://stackoverflow.com/questions/7644699/how-are-floating-point-numbers-stored-in-memory
1.....................23
8......1
seeeeeeeemmmmmmmmmmmmmmmmmmmmmmm meaning
31 0 bit #
signe
exponent
mantis
1.175494351 * 10^-38 < ... > 3.40282347 * 10^+38
2x10^-1 = 0.2x10^0 = 0.02x10^1 = 0.2
x 00000000 xxxxxxxx xxxxxxxx xxxxxxx special meanings (see bellow)
x 11111111 xxxxxxxx xxxxxxxx xxxxxxx //
x 00000001 xxxxxxxx xxxxxxxx xxxxxxx smallest exponent (-126)
x 01111111 xxxxxxxx xxxxxxxx xxxxxxx 0 is middle exponent (254 / 2 = 127)
x 11111110 xxxxxxxx xxxxxxxx xxxxxxx biggest exponent (+127)
x 00000000 00000000 00000000 0000000 0 (x can still be + or -)
x 11111111 00000000 00000000 0000000 +/- infinity
x 11111111 xxxxxxxx xxxxxxxx xxxxxx1 NaN (at least one non-zero mantissa digit)
x 00000000 xxxxxxxx xxxxxxxx xxxxxx1 denormalized numbers (same for mantissa)
---------------------------------------------------------
CONVERSIONS
---------------------------------------------------------
5.75
```
5 :
5 / 2 = 2 -> 1
2 / 2 = 1 -> 0
1 / 2 = 0 -> 1
75 :
.75 *2^2 = 2,88 ~= 3
(*2^x parce que c le moyen dont fait "bouger" la virgule
en base 2 (*10^x) en base 10)
3 / 2 = 1 -> 1
1 / 2 = 0 -> 1
101.11 = 2^2 + 2^0 + 2^-1 + 2^-2
= 4 + 1 + 0.5 + 0.25
```
0.875
```
.875 * 2^3 = 7 -> 0.111 * 2^3 = 111.0
7 / 2 = 3 -> 1
3 / 2 = 1 -> 1
1 / 1 = 0 -> 1
0.111
```
0.1875
```
-1 1875
0.1875 = 1.875 * 10^-1 = 01 11101010011
0.1875 = 0011
0*2^-1 + 082^-2 + 1*2^-3 + 1*2^-4
0 + 0 + .125 + .0625 = .1875
```
-43.625
```
-101011.101
fixed :
1 101011 101
-
101011
2^5 + 2^3 + 2^1 + 1
32 + 8 + 2 + 1 = 43
101
2^-1 + 2^-3
.5 + .125 = .625
```
-53.5 --> -110101.1
```
[ fixed : ]
1 110101 1
-
110101
2^5 + 2^4 + 2^2 + 1
32 + 16 + 4 + 1 = 53
1
2^-1
.5 = .5
[ float : ]
-1.101011 * 2^5
11.01011 -> 1
110.1011 -> 2
1101.011 -> 3
11010.11 -> 4
110101.1 -> 5
1 101 101011
-
2^2 + 1
4 + 1 = 5
101011
->1101011
```
.85
```
.85 * 2 = 1.7 [1] [.7]
.7 * 2 = 1.4 [1] [.4]
.4 * 2 = 0.8 [0] [.8]
.8 * 2 = 1.6 [1] [.6]
.6 * 2 = 1.2 [1] [.2]
.2 * 2 = 0.4 [0] [.4]
.4 * 2 = 0.8 [0] [.8]
.8 * 2 = 1.6 [1] [.6]
.6 * 2 = 1.2 [1] [.2]
.2 * 2 = 0.4 [0] [.4]
.4 * 2 = 0.8 [0] [.8]
.8 * 2 = 1.6 [1] [.6]
.6 * 2 = 1.2 [1] [.2]
.2 * 2 = 0.4 [0] [.4]
.4 * 2 = 0.8 [0] [.8]
.8 * 2 = 1.6 [1] [.6]
.6 * 2 = 1.2 [1] [.2]
.2 * 2 = 0.4 [0] [.4]
.4 * 2 = 0.8 [0] [.8]
.8 * 2 = 1.6 [1] [.6]
.6 * 2 = 1.2 [1] [.2]
.2 * 2 = 0.4 [0] [.4]
.4 * 2 = 0.8 [0] [.8]
...
-> 11011001100110011001100...
1 1 0 1 1 0 0 1 1 0 0 1 1
2^-1 + 2^-2 + 0 + 2^-4 + 2^-5 + 0 + 0 + 2^-8 + 2^-9 + 0 + 0 + 2^-12 + 2^-13
.5 + .25 + .0625 + .03125 + .00390625 + .001953125 + .000244140625 + .0001220703125
= .8499755859375
.5
.75
.8125
.84375
.84765625
.849609375
.849853515625
.8499755859375
```
.453125
```
.453125 *2 = 0.90625 [o] [.90625]
.90625 *2 = 1.8125 [1] [.8125]
.8125 *2 = 1.625 [1] [.625]
.625 *2 = 1.25 [1] [.25]
.25 *2 = 0.5 [0] [.5]
.5 *2 = 1 [1] []
-> .011101
```
---------------------------------------------------------
REPRESENTATION FLOATS vs INTEGERS
---------------------------------------------------------
```
integer : 1 (1)
floater : 0 01111111 00000000000000000000000 (1)
integer : 1010 (10)
floater : 0 10000010 01000000000000000000000 (10)
integer : 1100100 (100)
floater : 0 10000101 10010000000000000000000 (100)
integer : 1111101000 (1000)
floater : 0 10001000 11110100000000000000000 (1000)
integer : 00000000000000000000000000000010 (2)
floater : 0 10000000 00000000000000000000000 (2)
100010.1 (34.5)
floater : 0 10000100 00010 100000000000000000 (34.5)
100010.100011001100110011 (34.55)
floater : 0 10000100 00010 100011001100110011 (34.55)
1.0001100110011001101 (1.1)
floater : 0 01111111 00011001100110011001101 (1.1)
100010.01 (34.25)
floater : 0 10000100 00010 010000000000000000 (34.25)
10101.0011100001010001111 (21.22)
floater : 0 10000011 0101 0011100001010001111 (21.22)
110.11001100110011001101 (6.8)
floater : 0 10000001 10 110011001100110011010 (6.8)
```
---------------------------------------------------------
FLOATS -> FIXED
---------------------------------------------------------
par multiplications binaires :
```
100010.01 (34.25)
00100010 01000000 (8768)
00000001 00000000 (256)
100010.01000000 34.25
* 1 00000000.00000000 * 256.00
----------------------- --------
100010 01000000.0 8768.00
34.25 * (1 << _frac)
```
par decalage binaire :
```
0 10000100 00010 010000000000000000 (34.25) float
10000100 (132) decaler la virgule de 132 - 127 = 5
100010.01 (34.25) fixe
value = 34.25;
signe = (unsigned int)value;
exponent = ((unsigned int)(value << 1) >> 24) - 127;
fixedd = (unsigned int)(value << 9) >> (32 - exponent - 8);
```

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@@ -26,228 +26,3 @@ private:
#endif
//
// /// DECIMALE VS BINARY //////////////////////////////////////
//
// 11010101
//
// 1*10000000 | (128) | 2^7 | 128 *1 | 0 *2 +1
// 1*1000000 | (64) | 2^6 | + 64 *1 | 1 *2 +1
// 0*100000 | (32) | 2^5 | | 11 *2
// 1*10000 | (16) | 2^4 | + 16 *1 | 110 *2 +1
// 0*1000 | (8) | 2^3 | | 1101 *2
// 1*100 | (4) | 2^2 | + 4 *1 | 11010 *2 +1
// 0*10 | (2) | 2^1 | | 110101 *2
// 1*1 | (1) | 2^0 | + 1 *1 | 1101010 *2 +1
// | ______ |
// | 213 |
// 213
//
// 2*100 |(1100100)| 10^2 | 1100100 *2 | 0 *10 +2
// 1*10 | (1010)| 10^1 | + 1010 *1 | 2 *10 +1
// 3*1 | (1)| 10^0 | + 1 *3 | 21 *10 +3
// | | | ___________ | 213
// | | | 11010101 |
// |
// |
// 1100100 11001000 1 11010010 |
// * 2 + 1010 * 3 + 11 |
// _________ _________ ___ _________ |
// 11001000 11010010 11 11010101 |
//
//
// 213 -> 11010101
//
// 213 -128 = 85 | 213 /2 = 106 r 1
// 85 - 64 = 2 | 106 /2 = 53 r 0
// | 53 /2 = 26 r 1
// 21 - 16 = 5 | 26 /2 = 13 r 0
// | 13 /2 = 6 r 1
// 5 - 4 = 1 | 6 /2 = 3 r 0
// | 3 /2 = 1 r 1
// 1 - 1 = 0 | 1 /2 = 0 r 1
//
// 11010101 -> 213
//
// | 0*2 + 1 = 1
// | 1*2 + 1 = 3
// | 3*2 = 6
// | 6*2 + 1 = 13
// | 13*2 = 26
// | 26*2 + 1 = 53
// | 53*2 = 106
// | 106*2 + 1 = 213
//
//
//
// /// NEGATIVS INTEGERS ///////////////////////////////////////
//
// 5 0101 0 0000 0 0000 0000 0000 0000 0000 0000 0000 0000
// 1010 + 1 1 0001 1 0000 0000 0000 0000 0000 0000 0000 0001
// -5 1011 2 0010 2 0000 0000 0000 0000 0000 0000 0000 0010
// 3 0011 3 0000 0000 0000 0000 0000 0000 0000 0011
// 4 0100 4 0000 0000 0000 0000 0000 0000 0000 0100
// -> 5 0101 5 0000 0000 0000 0000 0000 0000 0000 0101
// 6 0110 6 0000 0000 0000 0000 0000 0000 0000 0110
// 7 0111 7 0000 0000 0000 0000 0000 0000 0000 0111
// ...
// 0111 1111 1111 1111 1111 1111 1111 1111 MAXINT
// 1000 0000 0000 0000 0000 0000 0000 0000 MININT
// ...
// 8 1000 -8 1111 1111 1111 1111 1111 1111 1111 1000
// 9 1001 -7 1111 1111 1111 1111 1111 1111 1111 1001
// 10 1010 -6 1111 1111 1111 1111 1111 1111 1111 1010
// -> 11 1011 -5 1111 1111 1111 1111 1111 1111 1111 1011
// 12 1100 -4 1111 1111 1111 1111 1111 1111 1111 1100
// 13 1101 -3 1111 1111 1111 1111 1111 1111 1111 1101
// 14 1110 -2 1111 1111 1111 1111 1111 1111 1111 1110
// 15 1111 -1 1111 1111 1111 1111 1111 1111 1111 1111
//
//
// /// FLOATS VS FIXED /////////////////////////////////////////
//
// 1.....................23
// 8......1
// seeeeeeeemmmmmmmmmmmmmmmmmmmmmmm meaning
// 31 0 bit #
//
// 2x10^-1 = 0.2x10^0 = 0.02x10^1 = 0.2
//
//
// -------------------------
//
// 5.75
//
// 5 :
// 5 / 2 = 2 -> 1
// 2 / 2 = 1 -> 0
// 1 / 2 = 0 -> 1
// 75 :
// .75 *2^2 = 2,88 ~= 3
// (*2^x parce que c le moyen dont fait "bouger" la virgule
// en base 2 (*10^x) en base 10)
// 3 / 2 = 1 -> 1
// 1 / 2 = 0 -> 1
// 101.11 = 2^2 + 2^0 + 2^-1 + 2^-2
// = 4 + 1 + 0.5 + 0.25
//
// -------------------------
//
// 0.875
//
// .875 * 2^3 = 7 -> 0.111 * 2^3 = 111.0
// 7 / 2 = 3 -> 1
// 3 / 2 = 1 -> 1
// 1 / 1 = 0 -> 1
// 0.111
//
// -------------------------
//
// 0.1875
// -1 1875
// 0.1875 = 1.875 * 10^-1 = 01 11101010011
// 0.1875 = 0011
// 0*2^-1 + 082^-2 + 1*2^-3 + 1*2^-4
// 0 + 0 + .125 + .0625 = .1875
//
//
// -------------------------
//
// -43.625
//
// -101011.101
// fixed :
// 1 101011 101
// -
// 101011
// 2^5 + 2^3 + 2^1 + 1
// 32 + 8 + 2 + 1 = 43
// 101
// 2^-1 + 2^-3
// .5 + .125 = .625
//
//
// -------------------------
//
// -53.5 --> -110101.1
//
// [ fixed : ]
// 1 110101 1
// -
// 110101
// 2^5 + 2^4 + 2^2 + 1
// 32 + 16 + 4 + 1 = 53
// 1
// 2^-1
// .5 = .5
// [ float : ]
// -1.101011 * 2^5
// 11.01011 -> 1
// 110.1011 -> 2
// 1101.011 -> 3
// 11010.11 -> 4
// 110101.1 -> 5
// 1 101 101011
// -
// 2^2 + 1
// 4 + 1 = 5
// 101011
// ->1101011
//
//
// -------------------------
//
// .85
//
// .85 * 2 = 1.7 [1] [.7]
// .7 * 2 = 1.4 [1] [.4]
// .4 * 2 = 0.8 [0] [.8]
// .8 * 2 = 1.6 [1] [.6]
// .6 * 2 = 1.2 [1] [.2]
// .2 * 2 = 0.4 [0] [.4]
// .4 * 2 = 0.8 [0] [.8]
// .8 * 2 = 1.6 [1] [.6]
// .6 * 2 = 1.2 [1] [.2]
// .2 * 2 = 0.4 [0] [.4]
// .4 * 2 = 0.8 [0] [.8]
// .8 * 2 = 1.6 [1] [.6]
// .6 * 2 = 1.2 [1] [.2]
// .2 * 2 = 0.4 [0] [.4]
// .4 * 2 = 0.8 [0] [.8]
// .8 * 2 = 1.6 [1] [.6]
// .6 * 2 = 1.2 [1] [.2]
// .2 * 2 = 0.4 [0] [.4]
// .4 * 2 = 0.8 [0] [.8]
// .8 * 2 = 1.6 [1] [.6]
// .6 * 2 = 1.2 [1] [.2]
// .2 * 2 = 0.4 [0] [.4]
// .4 * 2 = 0.8 [0] [.8]
// ...
// -> 11011001100110011001100...
// 1 1 0 1 1 0 0 1 1 0 0 1 1
// 2^-1 + 2^-2 + 0 + 2^-4 + 2^-5 + 0 + 0 + 2^-8 + 2^-9 + 0 + 0 + 2^-12 + 2^-13
// .5 + .25 + .0625 + .03125 + .00390625 + .001953125 + .000244140625 + .0001220703125
// = .8499755859375
// .5
// .75
// .8125
// .84375
// .84765625
// .849609375
// .849853515625
// .8499755859375
//
//
// -------------------------
//
// .453125
//
// .453125 *2 = 0.90625 [o] [.90625]
// .90625 *2 = 1.8125 [1] [.8125]
// .8125 *2 = 1.625 [1] [.625]
// .625 *2 = 1.25 [1] [.25]
// .25 *2 = 0.5 [0] [.5]
// .5 *2 = 1 [1] []
// -> .011101
//
//

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@@ -1,22 +1,40 @@
#include "Fixed.hpp"
/*
* function to print integers in binary
* functions to print numbers in binary
* for the float, found help from stackoverflow :
* https://stackoverflow.com/questions/474007/floating-point-to-binary-valuec
*/
void printBits(std::string before, unsigned int num)
std::string printBitsInt(int num)
{
int i = 0;
std::cout << before;
for (unsigned int mask = 1U << 31; mask; mask = mask >> 1)
std::cout << " ";
for (unsigned int mask = 1U << (sizeof(int) *8 -1); mask; mask >>= 1)
{
std::cout << ((num & mask) != 0);
i++;
if (i % 8 == 0)
// if (i % 8 == 0 && i < 32)
if (i == 1 || i == 9 || i == 24)
std::cout << ' ';
}
std::cout << "(" << (signed int)num << ")" << '\n';
return "";
}
std::string printBitsFloat(float num)
{
int *p = (int *)&num;
int i = 0;
for (unsigned int mask = 1U << (sizeof(float) *8 -1); mask; mask >>= 1)
{
std::cout << ((*p & mask) != 0);
i++;
if (i == 1 || i == 9)
std::cout << ' ';
}
return "";
}
/*
@@ -37,18 +55,18 @@ int const Fixed::_max = -1U >> (_frac +1);
*/
Fixed::Fixed() : _value(0) {
std::cout << "Default constructor called" << '\n';
// std::cout << "Default constructor called" << '\n';
return;
}
Fixed::Fixed(Fixed const & src) {
std::cout << "Copy constructor called" << '\n';
// std::cout << "Copy constructor called" << '\n';
*this = src;
return;
}
Fixed::~Fixed( void ) {
std::cout << "Destructor called" << '\n';
// std::cout << "Destructor called" << '\n';
return;
}
@@ -57,27 +75,26 @@ Fixed::~Fixed( void ) {
*/
Fixed::Fixed(int integer) {
std::cout << "Int constructor called" << '\n';
// std::cout << "Int constructor called" << '\n';
if (integer < ~this->_max || integer > this->_max)
{
std::cout << "error: integer out of range" << '\n';
return;
}
printBits("integer : ", integer);
std::cout << "integer : " << printBitsInt(integer) << " (" << integer << ")\n";
this->_value = integer << this->_frac;
printBits("integer : ", this->_value);
}
Fixed::Fixed(float const floater) {
std::cout << "Float constructor called" << '\n';
// std::cout << "Float constructor called" << '\n';
if (floater < ~this->_max || floater > this->_max)
{
std::cout << "error: float out of range" << '\n';
return;
}
std::cout << "floater : " << printBitsFloat(floater) << " (" << floater << ")\n";
}
@@ -86,7 +103,7 @@ Fixed::Fixed(float const floater) {
*/
Fixed & Fixed::operator=( Fixed const & rhs ) {
std::cout << "Copy assignment operator called" << '\n';
// std::cout << "Copy assignment operator called" << '\n';
if ( this != &rhs )
this->_value = rhs.getRawBits();
@@ -98,7 +115,7 @@ Fixed & Fixed::operator=( Fixed const & rhs ) {
*/
int Fixed::getRawBits( void ) const {
std::cout << "getRawBits member function called" << '\n';
// std::cout << "getRawBits member function called" << '\n';
return this->_value;
}
@@ -110,3 +127,5 @@ void Fixed::toFloat( void ) const {}
int Fixed::toInt( void ) const {
return 0;
}

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@@ -3,8 +3,7 @@
int main( void ) {
Fixed a( 1 );
Fixed const b( 1.5 );
Fixed a(1105979538);
// Fixed a;
// Fixed const b( 10 );