1# Bitwise Operation<a name="EN-US_TOPIC_0000001078588212"></a> 2 3- [Basic Concepts](#section1990715203418) 4- [Available APIs](#section848334511411) 5- [Development Example](#section67569495514) 6 - [Example Description](#section33551554391) 7 - [Verification](#section8931859194) 8 9 10## Basic Concepts<a name="section1990715203418"></a> 11 12A bitwise operation operates on a binary number at the level of its individual bits. For example, a variable can be set as a program PSW \(PSW\), and each bit \(flag bit\) in the PSW can have a self-defined meaning. 13 14## Available APIs<a name="section848334511411"></a> 15 16The system provides operations for setting the flag bit to **1** or **0**, changing the flag bit content, and obtaining the most significant bit and least significant bit of the flag bit 1 in a PSW. You can also perform bitwise operations on system registers. The following table describes the APIs available for the bitwise operation module. For more details about the APIs, see the API reference. 17 18**Table 1** Bitwise operation module APIs 19 20<a name="table148791521769"></a> 21<table><thead align="left"><tr id="row13880624615"><th class="cellrowborder" valign="top" width="16.89168916891689%" id="mcps1.2.4.1.1"><p id="p1587119571763"><a name="p1587119571763"></a><a name="p1587119571763"></a>Category</p> 22</th> 23<th class="cellrowborder" valign="top" width="35.54355435543554%" id="mcps1.2.4.1.2"><p id="p38714577610"><a name="p38714577610"></a><a name="p38714577610"></a>API</p> 24</th> 25<th class="cellrowborder" valign="top" width="47.56475647564757%" id="mcps1.2.4.1.3"><p id="p108711657563"><a name="p108711657563"></a><a name="p108711657563"></a>Description</p> 26</th> 27</tr> 28</thead> 29<tbody><tr id="row18801722069"><td class="cellrowborder" rowspan="2" valign="top" width="16.89168916891689%" headers="mcps1.2.4.1.1 "><p id="p108717579612"><a name="p108717579612"></a><a name="p108717579612"></a>Setting the flag bit to <strong id="b129301229122320"><a name="b129301229122320"></a><a name="b129301229122320"></a>1</strong> or <strong id="b1899463182312"><a name="b1899463182312"></a><a name="b1899463182312"></a>0</strong></p> 30</td> 31<td class="cellrowborder" valign="top" width="35.54355435543554%" headers="mcps1.2.4.1.2 "><p id="p88717574616"><a name="p88717574616"></a><a name="p88717574616"></a>LOS_BitmapSet</p> 32</td> 33<td class="cellrowborder" valign="top" width="47.56475647564757%" headers="mcps1.2.4.1.3 "><p id="p16871957668"><a name="p16871957668"></a><a name="p16871957668"></a>Sets a flag bit of a PSW to <strong id="b1283195411179"><a name="b1283195411179"></a><a name="b1283195411179"></a>1</strong>.</p> 34</td> 35</tr> 36<tr id="row38805219612"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p68713574610"><a name="p68713574610"></a><a name="p68713574610"></a>LOS_BitmapClr</p> 37</td> 38<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p14871155718618"><a name="p14871155718618"></a><a name="p14871155718618"></a>Sets a flag bit of a PSW to <strong id="b15267438112312"><a name="b15267438112312"></a><a name="b15267438112312"></a>0</strong>.</p> 39</td> 40</tr> 41<tr id="row16880112663"><td class="cellrowborder" rowspan="2" valign="top" width="16.89168916891689%" headers="mcps1.2.4.1.1 "><p id="p158710579615"><a name="p158710579615"></a><a name="p158710579615"></a>Obtaining the bit whose flag bit is <strong id="b58742415239"><a name="b58742415239"></a><a name="b58742415239"></a>1</strong></p> 42</td> 43<td class="cellrowborder" valign="top" width="35.54355435543554%" headers="mcps1.2.4.1.2 "><p id="p1787145718612"><a name="p1787145718612"></a><a name="p1787145718612"></a>LOS_HighBitGet</p> 44</td> 45<td class="cellrowborder" valign="top" width="47.56475647564757%" headers="mcps1.2.4.1.3 "><p id="p168713571468"><a name="p168713571468"></a><a name="p168713571468"></a>Obtains the most significant bit of <strong id="b485014714235"><a name="b485014714235"></a><a name="b485014714235"></a>1</strong> in the PSW.</p> 46</td> 47</tr> 48<tr id="row138803219613"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p15871957467"><a name="p15871957467"></a><a name="p15871957467"></a>LOS_LowBitGet</p> 49</td> 50<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p148719571569"><a name="p148719571569"></a><a name="p148719571569"></a>Obtains the least significant bit of <strong id="b9907125542319"><a name="b9907125542319"></a><a name="b9907125542319"></a>1</strong> in the PSW.</p> 51</td> 52</tr> 53<tr id="row0880182168"><td class="cellrowborder" rowspan="3" valign="top" width="16.89168916891689%" headers="mcps1.2.4.1.1 "><p id="p10871957265"><a name="p10871957265"></a><a name="p10871957265"></a>Operating continuous bits</p> 54</td> 55<td class="cellrowborder" valign="top" width="35.54355435543554%" headers="mcps1.2.4.1.2 "><p id="p787185717616"><a name="p787185717616"></a><a name="p787185717616"></a>LOS_BitmapSetNBits</p> 56</td> 57<td class="cellrowborder" valign="top" width="47.56475647564757%" headers="mcps1.2.4.1.3 "><p id="p10871135714613"><a name="p10871135714613"></a><a name="p10871135714613"></a>Sets the continuous flag bits of a PSW to <strong id="b145631313234"><a name="b145631313234"></a><a name="b145631313234"></a>1</strong>.</p> 58</td> 59</tr> 60<tr id="row12881728619"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p18710575615"><a name="p18710575615"></a><a name="p18710575615"></a>LOS_BitmapClrNBits</p> 61</td> 62<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p1387145711610"><a name="p1387145711610"></a><a name="p1387145711610"></a>Sets the continuous flag bits of a PSW to <strong id="b185031722103115"><a name="b185031722103115"></a><a name="b185031722103115"></a>0</strong>.</p> 63</td> 64</tr> 65<tr id="row4881192262"><td class="cellrowborder" valign="top" headers="mcps1.2.4.1.1 "><p id="p1987155714611"><a name="p1987155714611"></a><a name="p1987155714611"></a>LOS_BitmapFfz</p> 66</td> 67<td class="cellrowborder" valign="top" headers="mcps1.2.4.1.2 "><p id="p187115571369"><a name="p187115571369"></a><a name="p187115571369"></a>Obtains the first 0 bit starting from the least significant bit (LSB).</p> 68</td> 69</tr> 70</tbody> 71</table> 72 73## Development Example<a name="section67569495514"></a> 74 75### Example Description<a name="section33551554391"></a> 76 77This example implements the following: 78 791. Set a flag bit to **1**. 802. Obtain the most significant bit of flag bit 1. 813. Set a flag bit to **0**. 824. Obtains the least significant bit of the flag bit 1. 83 84``` 85#include "los_bitmap.h" 86#include "los_printf.h" 87 88static UINT32 BitSample(VOID) 89{ 90 UINT32 flag = 0x10101010; 91 UINT16 pos; 92 93 PRINTK("\nBitmap Sample!\n"); 94 PRINTK("The flag is 0x%8x\n", flag); 95 96 pos = 8; 97 LOS_BitmapSet(&flag, pos); 98 PRINTK("LOS_BitmapSet:\t pos : %d, the flag is 0x%0+8x\n", pos, flag); 99 100 pos = LOS_HighBitGet(flag); 101 PRINTK("LOS_HighBitGet:\t The highest one bit is %d, the flag is 0x%0+8x\n", pos, flag); 102 103 LOS_BitmapClr(&flag, pos); 104 PRINTK("LOS_BitmapClr:\t pos : %d, the flag is 0x%0+8x\n", pos, flag); 105 106 pos = LOS_LowBitGet(flag); 107 PRINTK("LOS_LowBitGet:\t The lowest one bit is %d, the flag is 0x%0+8x\n\n", pos, flag); 108 109 return LOS_OK; 110} 111``` 112 113### Verification<a name="section8931859194"></a> 114 115The development is successful if the return result is as follows: 116 117``` 118Bitmap Sample! 119The flag is 0x10101010 120LOS_BitmapSet: pos : 8, the flag is 0x10101110 121LOS_HighBitGet:The highest one bit is 28, the flag is 0x10101110 122LOS_BitmapClr: pos : 28, the flag is 0x00101110 123LOS_LowBitGet: The lowest one bit is 4, the flag is 0x00101110 124``` 125 126