Determining which flags are set from a hexadecimal input

2013 2 11
2 个回答
回答已采纳
4 次查看（30 天）

0 个投票

Hi,
I'm currently looking into writing a program which reads a hexadecimal input, and then tells me which flags are set depending on what the hex input is.
For e.g. input - hex = 0062
output - 'Byte 0 bit 1 is set' therefore parameter x - 'Byte 1 bit 0 is set' therefore parameter y - 'Byte 1 bit 3 is set' therefore parameter z
Could anyone assist in what the best way would be to program this code?
Thanks

请先登录，再回答此问题。

 采纳的回答

Thorsten
Thorsten 2013-2-11

0 个投票

function flags = which_bit_set(hex_str)
x = dec2bin(hex2dec('hex_str'));
for i = 1:length(x)
disp(['Bit ' int2str(i)])
if x(length(x) - i + 1) == '0'
disp(' not');
end
disp('set')
end

8 个评论
显示 6更早的评论 隐藏 6更早的评论

Darren
Darren 2013-2-27
Thanks Thorsten. How would you get this code to display a different word for each bit rather than every bit saying either set or not set?
i.e. bit 0 says either follow or not follow, bit 1 says either used or not used, bit 2 says ready or not ready etc?
Walter Roberson
Walter Roberson 2013-2-27
parmname = {'set', 'used', 'ready', ...};
[...]
disp(parmname{i})
Darren
Darren 2013-2-28
Where in the code to i enter those lines? I have tried the following:
function [ flags ] = which_bit_set(hex_str)
%UNTITLED3 Summary of this function goes here
% Detailed explanation goes here
x = dec2bin(hex2dec(hex_str));
for i = 0:7
disp(['Bit ' int2str(i)])
parmname = ['set', 'used', 'ready', 'past', 'help', 'seen', 'one', 'two'];
if x(7 - i + 1) == '0'
disp(parmname{i});
end
disp('set')
end
However, this keeps producing errors!
Walter Roberson
Walter Roberson 2013-2-28
function [ flags ] = which_bit_set(hex_str)
%UNTITLED3 Summary of this function goes here
% Detailed explanation goes here
parmname = {'set', 'used', 'ready', 'past', 'help', 'seen', 'one', 'two'}; %curly brackets!!
x = dec2bin(hex2dec(hex_str));
for i = 0:7
disp(['Bit ' int2str(i)])
if x(7 - i + 1) == '0'
disp('not')
end
disp(parmname{i});
end
Darren
Darren 2013-2-28
that code gives the following error:
Subscript indices must either be real positive integers or logicals.
Error in which_bit_set (line 13) disp(parmname{i});
Darren
Darren 2013-2-28
编辑：Darren 2013-2-28
Thanks Walter that error has fixed however the following error has occured:
Error in which_bit_set (line 4) parmname = {'set', 'used', 'ready', 'past', 'help', 'seen', 'one', 'two'}; %curly brackets!!
Output argument "flags" (and maybe others) not assigned during call to "C:\Documents\MATLAB\which_bit_set.m>which_bit_set".
Walter Roberson
Walter Roberson 2013-2-28
Adapt:
is_it_on = 'not ';
flags{i+1} = ['Bit ', int2str(i), is_it_on, parmname{i+1}]);

请先登录，再进行评论。

更多回答（1 个）

Jan
Jan 2013-2-11
编辑：Jan 2013-2-11

0 个投票

Perhaps this helps:
Str = '0062';
Num = sscanf(Str, '%.2x'); % Or is it '%2x'? Or HEX2DEC()
for iByte = 1:2
Byte = Num(iByte);
for iBit = 0:7
value = bitget(Byte, iBit);
fprintf('Byte %d Bit %d: %d', iByte, iBit, value);
end
end
This does not hit the "therefore parameter x" part, but I do not understand this expression.

类别

在 帮助中心 和 File Exchange 中查找有关 Just for fun 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by