Its syntax is:. Everything written before END will be part of the string "str" with whitespaces and newlines preserved. Let's see an example on this:. You can see that the. In Perl, strings and numbers are seamlessly converted into each other depending on the context in which they are used. An example will make it clear. And this is what I was trying to say that in Perl, strings and numbers are converted into each other according to the requirement.
It means that int Let's see an example for the same. There are many others in Perl. You know how to print something on the screen. In the next chapter, you will learn to take input from the keyboard. Swapping means interchanging the values of two variables. So, let's see how it is done. Suppose you have a variable having a value of 3. It means that you can print only 3. Let's first see an example:.
Prev Next. New Questions Write a program to check if the elements of an array are the same or not. No, it's not. It's a number, and the OP really does want to convert it to binary. Binary is a text representation of a number just like decimal, octal and hexadecimal. It's a number, You were responding to my assertion that the integer was already in binary and could be printed in different bases with printf. Yes, an integer is a number but that doesn't mean it is not stored as binary in memory.
According to perlnumber an integer is represented in Perl as a native integer according to the C compiler used to build Perl. Maybe I have assumed Perl is more like C than it really is. I was referring to how it is stored in memory and that you can use printf to display the value in other bases or even in binary. Back to Seekers of Perl Wisdom. Comment on convert to binary number. Replies are listed 'Best First'. PerlMonks lovingly hand-crafted by Tim Vroom. PerlMonks somehow became entangled with The Perl Foundation.
Is your data what you think it is? Need Help?? Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question: Hi all. Comment on convert to binary number Replies are listed 'Best First'. Is your number an integer?
Is it stored in a file, in a perl variable, the perl code, or other? Do you want to address individual bits in the result, or do you want to display it on your screen? Write it to a file? Or other? You probably have already received the right answer.
To get the permissions, I just have to know and use the right bit masks. In this case, I specify them in octal, which corresponds to the representation I use for chmod and mkdir either in Perl or on the command line :. Can you tell which one does what just by looking at them? The bitwise OR operator, , returns the bits set in either or both operand.
If a position in either argument has the bit set, the result has that bit set. I often use these to combine values, and you may have already been using them with operators such as sysopen and flock. Those built-ins take an argument that constrains or allows their action, and I build up those values by OR-ing values.
Each of the values specifies a setting. The result is the combination of all of the settings. The third argument to sysopen is its mode. If I knew the bit values for the mode settings, I could use them directly, but they might vary from system to system. I use the values from Fcntl instead. For file locking, I OR the settings I want to get the right effect. The Fcntl module supplies the values as constants. By OR-ing those constants, I form the right bit pattern to send to flock :.
Although I simply exited the program in this example, I might want to sleep for a bit and try again, or do something else until I can get the lock. That is, that bit can only be set in one of the arguments for it to be set in the result:. It turns out that they differ in exactly one bit.
I want to see the bit patterns that led to this. How do I get that value? First, I get the values for the upper- and lowercase versions of the letter P :. The lowercase characters in ASCII have the same bit values except for the bit 5, putting all the lowercase characters 32 positions above the uppercase ones:. The bit-shift operators do not wrap values to the other end, although I could write my own subroutine to do that.
The length of my values depends on my particular architecture, just as I discussed earlier. I use the bit-shift operator with the return value from system , which is two bytes or whatever the libc version of wait returns. I simply shift everything to the right eight positions. I have to know the proper masks:. Bit vectors can save memory by using a single scalar to hold many values. I can use a long string of bits to store the values instead of using an array of scalars.
Even the empty scalar takes up some memory; I have to pay for that scalar overhead with every scalar I create. Using Devel::Size , I can look at the size of a scalar:. On my MacBook running Perl 5. The output shows me that Perl has already set up some infrastructure to handle the scalar value:. Even with nothing in it, the scalar variable has a reference count and the scalar flags. Now, imagine an array of several hundred or thousand scalar values, each with their own scalar overhead.
If I have enough data and another way to store it and then access it, I can save a lot of memory by avoiding the Perl variable overhead. The easiest thing I can do is use a long string where each character or other number of characters represents an element. Instead of storing the sequence as an array of scalars each holding one character or even objects representing that base , I store them as sequential characters in a single string where I only get the scalar overhead once:.
I can then access the string with substr , which I give a starting position and a length:. Of course, I can hide these operations behind functions, or I can even make an object out of the string and call methods on it to get or change the parts I want. I can shove several different types into a string and pull them out again. A bit vector does the same thing as the single string or the packed string.
In one scalar value, it stores several values. The built-in vec function treats a string as a bit vector. It divides the string into elements according to the bit size I specify, although that number has to be a power of two. I can use any string that I like. In this example I use 8 for the bit size, which corresponds to single-byte characters:.
I can also start from scratch to build up the string. The vec function is an lvalue so I can assign to it. As with other things in Perl, the first element has the index 0. When using vec on a string, Perl treats it as a byte string, tossing away any other encoding that the string may have had. That is, vec can operate on any string, but it turns it into a byte string.
I can use vec to extract part of the string without affecting the UTF8 flag. Finally, once I change the string through vec , Perl treats it as a simple series of bytes. When I change the initial H to a W , Perl forgets all about the encoding. If I want to keep the string value, I should do something else:. The actual storage gets a bit tricky, so making a change and then inspecting the scalar I use to store everything, it may seem like the wrong thing is happening.
Perl actually stores the bit vector as a string, so on inspection, I most likely see a lot of nonsense:. With eight bits per element, Perl uses one byte for each element. The first element in the bit vector is the first byte, the second is the second byte, and so on. The first part of my program creates a string I can recognize, and I see the characters in the order I added them:. The second part of the program is different. I set the bit size to 4 and add several numbers to it.
If I use one, two, or four bits per element, Perl still treats the string as bytes, but then orders the bits in a little-endian fashion. The proper order of the elements is A, B, C, D, but vec starts with the lower part of each byte, which is to the right, and fills the byte up towards the left before moving to the next byte:.
I wrote a little program to illustrate the ordering of the elements. If I really need to see the bit vector in ones and zeros, I can use unpack with the b format. This orders the bits in the way I would naturally expect, instead of the tricky order I showed when using a bit length less than 8 with vec :. Instead of using a whole character eight bits to store each one of those as I did previously, I can use just two bits. In this example, I turn a character string into a bit vector that is only 3 bytes long:.
I give vec three arguments: the bit vector, the number of the element, and the width in bits of each element. I use the value that vec returns to look up the base symbol in the hash, which maps both ways:. I could get more fancy by using four bits per element and using each bit to represent a base. He represents each puzzle row with nine bits, one for each square, and turns on a bit when that square has a value.
A row might look like:. For each of the 9 rows in the puzzle, he adds another 9 bits, ending up with a bit string 81 bits long for all of the squares. Once any square has a value, he can eliminate all of the other solutions that also have a value in that square. Perl does its own sprintf formatting: it emulates the C function sprintf 3 , but doesn't use it except for floating-point numbers, and even then only standard modifiers are allowed. Non-standard extensions in your local sprintf 3 are therefore unavailable from Perl.
Unlike printf , sprintf does not do what you probably mean when you pass it an array as your first argument. The array is given scalar context, and instead of using the 0th element of the array as the format, Perl will use the count of elements in the array as the format, which is almost never useful. Perl's sprintf permits the following universally-known conversions:. Finally, for backward and we do mean "backward" compatibility, Perl permits these unnecessary but widely-supported conversions:.
In other words, 1. In order, these are:. By default sprintf will format the next unused argument in the list, but this allows you to take the arguments out of order:. This flag tells Perl to interpret the supplied string as a vector of integers, one for each character in the string. Perl applies the format to each integer in turn, then joins the resulting strings with a separator a dot. This can be useful for displaying ordinal values of characters in arbitrary strings:. Arguments are usually formatted to be only as wide as required to display the given value.
You can specify a precision for numeric conversions or a maximum width for string conversions by specifying a. For floating-point formats except g and G , this specifies how many places right of the decimal point to show the default being 6. For example:. For "g" and "G", this specifies the maximum number of significant digits to show; for example:. For integer conversions, specifying a precision implies that the output of the number itself should be zero-padded to this width, where the 0 flag is ignored:.
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Comment on convert to binary number Replies are listed 'Best First'. Is your number an integer? Is it stored in a file, in a perl variable, the perl code, or other? Do you want to address individual bits in the result, or do you want to display it on your screen? Write it to a file? Or other? You probably have already received the right answer. All you have to do is choose the one that guessed the right answers to these questions. That may not be easy. I suggest that you tell us what you want to accomplish.
It probably can be done without your conversion at all. If it is required, we will be able to give you the answer that best fits your real needs. Well, it is normally a binary number already, but not if it's embedded in something that Perl will treat as a string.
For example an IP address expressed with 3 dot delimiters between four numbers and you want to convert the whole thing to one binary number. But yes, lookup pack in perldoc as choroba suggests. One world, one people. It is already a binary number. It's electrons caught in little bits of silicon, pretending to be bits, pretending to be numbers.
I was surprised by your statement "No, it's not. Some notes below your chosen depth have not been shown here. Log In? How do I use this? Other CB clients. The St. Little endian Intel, least significant byte first and big endian Motorola, most significant byte first byte order are supported. This option controls the type that enumeration constants will have in data structures returned by the unpack method.
If you have the following definitions:. Enumeration constants are returned as plain integers. This is fast, but may be not very useful. It is also the default. Enumeration constants are returned as strings. This will create a string constant for every unpacked enumeration constant and thus consumes more time and memory. However, the result may be more useful. Enumeration constants are returned as double typed scalars. If evaluated in string context, the enumeration constant will be a string, if evaluated in numeric context, the enumeration constant will be an integer.
This option allows you to selectively deactivate certain keywords in the C parser. If you do. But if you parse this with an ANSI compiler, it will be a syntax error. To parse the above code correctly, you have to disable the void keyword in the Convert::Binary::C parser:.
By default, the Convert::Binary::C parser will recognize the keywords inline and restrict. If your compiler doesn't have these new keywords, it usually doesn't matter. Only if you're using the keywords as identifiers, like in. This option allows you to add new keywords to the parser. These new keywords can either be mapped to existing tokens or simply ignored. The first one obviously is a synonym for signed , while the second one is only a marker for a language extension.
Instead of utilizing the preprocessor, you'll have to create mappings for the new keywords directly in the parser using KeywordMap. This could be done with the following code:. You can specify any valid identifier as hash key, and either a valid C keyword or undef as hash value. Having configured the object that way, you could parse even. Note that KeywordMap and DisabledKeywords perfectly work together. Use this boolean option if you want characters to be unsigned if specified without an explicit signed or unsigned type specifier.
By default, characters are signed. Use this boolean option if you want bitfields to be unsigned if specified without an explicit signed or unsigned type specifier. By default, bitfields are signed. Use this boolean option if you want warnings to be issued during the parsing of source code. Currently, warnings are only reported by the preprocessor, so don't expect the output to cover everything.
By default, warnings are turned off and only errors will be reported. However, even these errors are turned off if you run without the -w flag. If this is enabled which is the default , you can use variable length argument lists in your preprocessor macros. When set to undef , the macro will not be defined. Use this option to set the include path for the internal preprocessor.
The option value is a reference to an array of strings, each string holding a directory that should be searched for includes. Use this option to define symbols in the preprocessor. The option value is, again, a reference to an array of strings. Each string can be either just a symbol or an assignment to a symbol. This is completely equivalent to what the -D option does for most preprocessors.
Use this option to make assertions in the preprocessor. If you don't know what assertions are, don't be concerned, since they're deprecated anyway. They are, however, used in some system's include files. The value is an array reference, just like for the macro definitions. Only the way the assertions are defined is a bit different and mimics the way they are defined with the assert directive:.
When using unpack on compounds and iterating over the returned hash, the order of the compound members is generally not preserved due to the nature of hash tables. It is not even guaranteed that the order is the same between different runs of the same program.
This can be very annoying if you simply use to dump your data structures and the compound members always show up in a different order. By setting OrderMembers to a non-zero value, all hashes returned by unpack are tied to a class that preserves the order of the hash keys. This way, all compound members will be returned in the correct order just as they are defined in your C code.
If more than one of these modules is installed, Convert::Binary::C will use them in that order of preference. When using this option, you should keep in mind that tied hashes are significantly slower and consume more memory than ordinary hashes, even when the class they're tied to is implemented efficiently. So don't turn this option on if you don't have to. Use this option to specify and configure a bitfield layouting engine.
You can choose an engine by passing its name to the Engine option, like:. It does not handle packed bitfields yet. This engine implements the behaviour of Microsoft's cl compiler. It should be fairly complete and can handle packed bitfields. This engine is only used for testing the bitfield infrastructure in Convert::Binary::C. There's usually no reason to use it. You can reconfigure all options even after you have parsed some code.
The changes will be applied to the already parsed definitions. This works as long as array lengths are not affected by the changes. If you have Alignment and IntSize set to 4 and parse code like this. If you reconfigure the alignment to 1 now, the size of foo is now 5 instead of 8. While the alignment is adjusted correctly, the number of elements in array zap will still be 16 and will not be changed to Parses a string of valid C code. All enumeration, compound and type definitions are extracted.
On success, the method returns a reference to its object. Parses a C source file. The state of the preprocessor is also saved, so you may also use defines from a previous parse. This works only as long as the preprocessor is not reset. See "Preprocessor configuration" for details. When you're parsing C source files instead of C header files, note that local definitions are ignored.
This means that type definitions hidden within functions will not be recognized by Convert::Binary::C. This is necessary because different functions even different blocks within the same function can define types with the same name:. The above is a valid piece of C code, but it's not possible for Convert::Binary::C to distinguish between the different definitions of enum digit , as they're only defined locally within the corresponding block. You can use this method if you want to parse some entirely different code, but with the same configuration.
The above code is technically equivalent Mostly. Actually, using sourcify and parse might alter the order of the parsed data, which would make methods such as compound return the definitions in a different order. If you need to know if a definition for a certain type name exists, use this method.
You pass it the name of an enum, struct, union or typedef, and it will return a non-empty string being either "enum" , "struct" , "union" , or "typedef" if there's a definition for the type in question, an empty string if there's no such definition, or undef if the name is completely unknown. If the type can be interpreted as a basic type, "basic" will be returned. If you pass in a TYPE , the output will be slightly different. If the specified member exists, the def method will return "member".
If the member doesn't exist, or if the type cannot have members, the empty string will be returned. Again, if the name of the type is completely unknown, undef will be returned. This may be useful if you want to check if a certain member exists within a compound, for example. So, if def returns a non-empty string, you can safely use any other method with that type's name or with that member expression.
Concerning arrays, note that the index into an array doesn't need to be within the bounds of the array's definition, just like in C. In the above example, quad and quad[-3] are valid members of the quad array, even though it is declared to have only four elements. You could however force interpretation as an enum, struct or union by putting "enum" , "struct" or "union" in front of the type's name.
You can use the defined method to find out if a certain macro is defined, just like you would use the defined operator of the preprocessor. For example, the following code. You have to keep in mind that this works only as long as the preprocessor is not reset. Use this method to pack a complex data structure into a binary string according to a type definition that has been previously parsed.
DATA must be a scalar matching the type definition. C structures and unions are represented by references to Perl hashes, C arrays by references to Perl arrays. Elements not defined in the Perl data structure will be set to zero in the packed byte string. If you pass undef as or simply omit the second parameter, the whole string will be initialized with zero bytes.
On success, the packed byte string is returned. If TYPE refers to a compound object, you may pack any member of that compound object. Simply add a member expression to the type name, just as you would access the member in C:. If called in a void context, pack will directly modify the string you passed as the third argument.
Otherwise, a copy of the string is created, and pack will modify and return the copy, so the original string will remain unchanged. The 3-argument version may be useful if you want to change only a few members of a complex data structure without having to unpack everything, change the members, and then pack again which could waste lots of memory and CPU cycles.
So, instead of doing something like. Besides this code being a lot shorter and perhaps even more readable , it can be significantly faster if you're dealing with really big data blocks. If the length of the input string is less than the size required by the type, the string or its copy is extended and the extended part is initialized to zero.
If the length is more than the size required by the type, the string is kept at that length, and also a copy would be an exact copy of that string. Use this method to unpack a binary string and create an arbitrarily complex Perl data structure based on a previously parsed type definition. On failure, e. On success, a reference to a complex Perl data structure is returned, which can directly be dumped using the Data::Dumper module:.
If TYPE refers to a compound object, you may unpack any member of that compound object. The initializer method can be used retrieve an initializer string for a certain TYPE. This can be useful if you have to initialize only a couple of members in a huge compound type or if you simply want to generate initializers automatically.
You could directly put that into a C program, although it probably isn't very useful yet. It becomes more useful if you actually specify how you want to initialize the type:. As only the first member of a union can be initialized, choice. You will not be warned about the fact that you probably tried to initialize a member other than the first. This is considered a feature, because it allows you to use unpack to generate the initializer data:. Since unpack unpacks all union members, you would otherwise have to delete all but the first one previous to feeding it into initializer.
Also, stuff is ignored, because it actually isn't a member of data. You won't be warned about that either. This method will return the size of a C type in bytes. If it cannot find the type, it will throw an exception. If the type defines some kind of compound object, you may ask for the size of a member of that compound object:.
This method will return the type of a C member. While this only makes sense for compound types, it's legal to also use it for non-compound types. The typeof method can be used on any valid member , even on arrays or unnamed types. If the type is a bitfield, the type name is followed by a colon and the number of bits. Given the above C code has been parsed, calls to typeof would return the following values:. You can use offsetof just like the C macro of same denominator. The first iteration simply shows that the offset of zap.
You may additionally specify a member for the type passed as the first argument, as shown in the second iteration. The offset suffix is also supported by offsetof , so the third iteration will correctly print The last iteration demonstrates that even out-of-bounds array indices are handled correctly, just as they are handled in C.
You can think of member as being the reverse of the offsetof method. However, as this is more complex, there's no equivalent to member in the C language. Usually this method is used if you want to retrieve the name of the member that is located at a specific offset of a previously parsed type.
The output of the first iteration is obvious. The member zap. In the second iteration, the offset points into a region of padding bytes and thus no member of week can be named. Instead of a member name the offset relative to zap is appended. In the third iteration, the offset points to zap.
However, zap. The last iteration causes an exception because the offset of 99 is not valid for struct test since the size of struct test is only You might argue that this is inconsistent, since offsetof can also handle out-of-bounds array members.
But as soon as you have more than one level of array nesting, there's an infinite number of out-of-bounds members for a single given offset, so it would be impossible to return a list of all members. Like offsetof , member also works on array types:. While the behaviour for struct s is quite obvious, the behaviour for union s is rather tricky.
As a single offset usually references more than one member of a union, there are certain rules that the algorithm uses for determining the best member. If no member is referenced without an offset, the first non-compound member that is referenced with an offset will be returned. The Type column shows the result of the typeof method when passing the corresponding member.
It's like having a stack of all the union members and looking through the stack for the shiniest piece you can see. The beginning of a member denoted by uppercase letters is always shinier than the rest of a member, while padding regions denoted by dashes aren't shiny at all. If you look through that stack from top to bottom, you'll end up at the parenthesized members.
Alternatively, if you're not only interested in the best member, you can call member in list context, which makes it return all members referenced by the given offset. The first member returned is always the best member. The other members are sorted according to the rules given above.
This means that members referenced without an offset are followed by members referenced with an offset. Padding regions will be at the end. The tag method can be used to tag properties to a TYPE. It's a bit like having configure for individual types. Note that while you can tag whole types as well as compound members, it is not possible to tag array members, i. To see if a tag is attached to a type or to get the value of a tag, pass only the type and tag name to tag :. To see which tags are attached to a type, pass only the type.
The tag method will now return a hash reference containing all tags attached to the type:. If called as a 'set' method, it will return a reference to its object, allowing you to chain together consecutive method calls. Note that when a compound is inlined, tags attached to the inlined compound are ignored, for example:. As you can see from the above output, tags attached to members of inlined compounds header. The Format tag allows you to control the way binary data is converted by pack and unpack.
If you tag it as String , it will be treated like a null-terminated C string, i. This is useful if you cannot use flexible array members in your source code. You can also tag an array to have a fixed size different from the one it was originally declared with.
If the array is a member of a compound, you can also tag it with to have a size corresponding to the value of another member in that compound. Finally, you can specify a subroutine that is called when the size of the array needs to be determined. By default, and if the array is a compound member, that subroutine will be passed a reference to the hash storing the data for the compound. You can also instruct Convert::Binary::C to pass additional arguments to the subroutine by passing an array reference instead of the subroutine reference.
This array contains the subroutine reference as well as a list of arguments. It is possible to define certain special arguments using the arg method. Hooks are called whenever a certain TYPE is packed or unpacked. Hooks are currently considered an experimental feature. SUB is a reference to a subroutine that usually takes one input argument, processes it and returns one output argument. Alternatively, you can pass a custom list of arguments to the hook by using an array reference instead of SUB that holds the subroutine reference in the first element and the arguments to be passed to the subroutine as the other elements.
This way, you can even pass special arguments to the hook using the arg method. As long as you don't explicitly overwrite a previously registered hook, it won't be modified or removed by registering other hooks for the same TYPE. To remove only a single hook, pass undef as SUB instead of a subroutine reference:. Use the untag method to remove one, more, or all tags from a type. If you don't pass any tag names, all tags attached to the type will be removed.
Otherwise only the listed tags will be removed. Creates placeholders for special arguments to be passed to hooks or other subroutines. These arguments are currently:. A reference to the calling Convert::Binary::C object. This may be useful if you need to work with the object inside the subroutine. Note that not all arguments may be supported depending on the context of the subroutine.
In scalar context, the method returns a hash reference. Each key is the name of a file. The values are again hash references, each of which holds the size, modification time mtime , and change time ctime of the file at the moment it was parsed. In list context, the method returns the names of all files that have been parsed, i. Returns a string that holds the C source code necessary to represent all parsed C data structures.
The purpose of the sourcify method is to enable some kind of platform-independent caching. The C code generated by sourcify can be parsed by any standard C compiler, as well as of course by the Convert::Binary::C parser. However, the code may be significantly shorter than the code that has originally been parsed.
When parsing a typical header file, it's easily possible that you need to open dozens of other files that are included from that file, and end up parsing several hundred kilobytes of C code. Since most of it is usually preprocessor directives, function prototypes and comments, the sourcify function strips this down to a few kilobytes.
Saving the sourcify string and parsing it next time instead of the original code may be a lot faster. The sourcify method takes a hash reference as an optional argument. It can be used to tweak the method's output. The following options can be configured. Turns preprocessor context information on or off. If this is turned on, sourcify will insert line preprocessor directives in its output.
So in the above example. Note that "[buffer]" refers to the here-doc buffer when using parse. Turn this on if you want all the defined macros to be part of the source code output. Given the example code above. The macro definitions always appear at the end of the source code. The order of the macro definitions is undefined. The following methods can be used to retrieve information about the definitions that have been parsed.
The examples given in the description for enum , compound and typedef all assume this piece of C code has been parsed:. Returns a list of identifiers of all defined enumeration objects. Enumeration objects don't necessarily have an identifier, so something like. Also, enumerations that are not defined within the source code - like in. The only way to retrieve a list of all enumeration identifiers is to use the enum method without additional arguments.
You can get a list of all enumeration objects that have an identifier by using. Returns a list of references to hashes containing detailed information about all enumerations that have been parsed. If a list of enumeration identifiers is passed to the method, the returned list will only contain hash references for those enumerations. The enumeration identifiers may optionally be prefixed by enum. If an enumeration identifier cannot be found, the returned list will contain an undefined value at that position.
In scalar context, the number of enumerations will be returned as long as the number of arguments to the method call is not 1. In the latter case, a hash reference holding information for the enumeration will be returned. This is the filename followed by the line number in parentheses. One useful application may be to create a hash table that holds all enumerators of all defined enumerations:.
Returns a list of identifiers of all structs and unions compound data structures that are defined in the parsed source code. Like enumerations, compounds don't need to have an identifier, nor do they need to be defined. Again, the only way to retrieve information about all struct and union objects is to use the compound method and don't pass it any arguments. If you should need a list of all struct and union identifiers, you can use:.
Returns a list of references to hashes containing detailed information about all compounds structs and unions that have been parsed. The identifiers may optionally be prefixed by struct or union , which limits the search to the specified kind of compound. If an identifier cannot be found, the returned list will contain an undefined value at that position. In scalar context, the number of compounds will be returned as long as the number of arguments to the method call is not 1.
In the latter case, a hash reference holding information for the compound will be returned. The list returned by the compound method looks similar to this:. This may be a string or a reference to a hash describing the type.
It may be useful to have separate lists for structs and unions. One way to retrieve such lists would be to use. However, you should use the struct and union methods, which is a lot simpler:. Returns a list of all defined struct identifiers. Returns a list of all defined union identifiers. Returns a list of all defined typedef identifiers. Typedefs that do not specify a type that you could actually work with will not be returned.
Returns a list of references to hashes containing detailed information about all typedefs that have been parsed. If a list of typedef identifiers is passed to the method, the returned list will only contain hash references for those typedefs. In scalar context, the number of typedefs will be returned as long as the number of arguments to the method call is not 1. In the latter case, a hash reference holding information for the typedef will be returned. The list returned by the typedef method looks similar to this:.
See enum and compound for a description on how to interpret this hash. If a list of macro names is passed to the method, the returned list will only contain the definitions for those macros. For undefined macros, undef will be returned. The feature function returns 1 if the feature is enabled, 0 if the feature is disabled, and undef if the feature is unknown.
Currently the only features that can be checked are ieeefp and debug. Returns the value of a property of the native system that Convert::Binary::C was built on. The following properties can be queried:. You can also call native without arguments, in which case it will return a reference to a hash with all properties, like:.
The contents of that hash are suitable for passing them to the configure method. Like perl itself, Convert::Binary::C can be compiled with debugging support that can then be selectively enabled at runtime. You can specify whether you like to build Convert::Binary::C with debugging support or not by explicitly giving an argument to Makefile.
The default will depend on how your perl binary was built. Once you have built Convert::Binary::C with debugging support, you can use the following syntax to enable debug output. Instead of. However, I don't recommend to enable all debug output, because that can be a fairly large amount. Instead of saying all , you can pass a string that consists of one or more of the following characters:.
So the following might give you a brief overview of what's going on inside Convert::Binary::C:. By default, all debug output is written to stderr. You can, however, redirect the debug output to a file with the debugfile option:. If the file cannot be opened, you'll receive a warning and the output will go the stderr way again.
If Convert::Binary::C is built without debugging support, passing the debug or debugfile options will cause a warning to be issued. The corresponding environment variables will simply be ignored. Setting this variable to a non-zero value will globally turn on hash key ordering for compound members. Have a look at the OrderMembers option for details. Setting the variable to the name of a perl module will additionally use this module instead of the predefined modules for member ordering to tie the hashes to.
If Convert::Binary::C is built with debugging support, you can use this variable to specify the debugging options. If Convert::Binary::C is built with debugging support, you can use this variable to redirect the debug output to a file. This variable is intended purely for development. Setting it to a non-zero value disables the Convert::Binary::C parser, which means that no information is collected from the file or code that is parsed.
However, the preprocessor will run, which is useful for benchmarking the preprocessor. Flexible array members are a feature introduced with ISO-C It's a common problem that you have a variable length data field at the end of a structure, for example an array of characters at the end of a message struct. ISO-C99 allows you to write this as:.
The advantage is that you clearly indicate that the size of the appended data is variable, and that the data member doesn't contribute to the size of the message structure. When packing or unpacking data, Convert::Binary::C deals with flexible array members as if their length was adjustable.
For example, unpack will adapt the length of the array depending on the input string:. You can also alter the length of an array using the Dimension tag. When using Convert::Binary::C to handle floating point values, you have to be aware of some limitations. You're usually safe if all your platforms are using the IEEE floating point format. During the Convert::Binary::C build process, the ieeefp feature will automatically be enabled if the host is using IEEE floating point.
You can check for this feature at runtime using the feature function:. When IEEE floating point support is enabled, the module can also handle floating point values of a different byteorder. If your host platform is not using IEEE floating point, the ieeefp feature will be disabled. Convert::Binary::C then will be more restrictive, refusing to handle any non-native floating point values. However, Convert::Binary::C cannot detect the floating point format used by your target platform.
It can only try to prevent problems in obvious cases. If you know your target platform has a completely different floating point format, don't use floating point conversion at all. Whenever Convert::Binary::C detects that it cannot properly do floating point value conversion, it will issue a warning and will not attempt to convert the floating point value.
Bitfield support in Convert::Binary::C is currently in an experimental state. You are encouraged to test it, but you should not blindly rely on its results. You are also encouraged to supply layouting algorithms for compilers whose bitfield implementation is not handled correctly at the moment. Even better that the plain algorithm is of course a patch that adds a new bitfield layouting engine.
While bitfields may not be handled correctly by the conversion routines yet, they are always parsed correctly. This means that you can reliably use the declarator fields as returned by the struct or typedef methods. Given the following source. If you wish to derive a new class from Convert::Binary::C, this is relatively easy. The XS data is stored in a read-only hash value for the key that is the empty string. So it is safe to use any non-empty hash key when deriving your own class.
In addition, Convert::Binary::C does quite a lot of checks to detect corruption in the object hash. If you store private data in the hash, you should override the clone method and provide the necessary code to clone your private data. Most of the time when you're really looking for Convert::Binary::C you'll actually end up finding one of the following modules. Some of them have different goals, so it's probably worth pointing out the differences. Like Convert::Binary::C, this module aims at doing conversion from and to binary data based on C types.
However, its configurability is very limited compared to Convert::Binary::C. Also, it does not parse all C code correctly. It's slower than Convert::Binary::C, doesn't have a preprocessor. On the plus side, it's written in pure Perl. This module doesn't allow you to reuse your C source code. One main goal of Convert::Binary::C was to avoid code duplication or, even worse, having to maintain different representations of your data structures.
This module has a special purpose. Alexis Denis for making me improve externally and simplify internally floating point support. He can also be blamed indirectly for the initializer method, as I need it in my effort to support bitfields some day. Michael J. James Roskind, as his C parser was a great starting point to fix all the problems I had with my original parser based only on the ANSI ruleset.
I'm sure there are still lots of bugs in the code for this module. Some features in Convert::Binary::C are marked as experimental. This has most probably one of the following reasons:. The feature does not behave in exactly the way that I wish it did, possibly due to some limitations in the current design of the module. The feature hasn't been tested enough and may completely fail to produce the expected results. I hope to fix most issues with these experimental features someday, but this may mean that I have to change the way they currently work in a way that's not backwards compatible.
So if any of these features is useful to you, you can use it, but you should be aware that the behaviour or the interface may change in future releases of this module. Copyright c Marcus Holland-Moritz. All rights reserved. The ucpp library is c Thomas Pornin. See ccconfig , perl , perldata , perlop , perlvar , Data::Dumper and Scalar::Util. For more information on module installation, please visit the detailed CPAN module installation guide.
Background and History In late I wrote a real-time debugging interface for an embedded medical device that allowed me to send out data from that device over its integrated Ethernet adapter. All in all, this little module seemed to make my task a bit easier, but it was far from being what I was thinking of: A module that could directly use the source I've been coding for the embedded device without any modifications.
About this document This document describes how to use Convert::Binary::C. For example, perldoc perl will show you Perl's main manpage. To look up a specific Perl function, use perldoc -f : perldoc -f map gives you more information about the map function. You can also search the FAQ using perldoc -q : perldoc -q array will give you everything you ever wanted to know about Perl arrays. Why use Convert::Binary::C? Next, you need to create a new Convert::Binary::C object.
Configuring the object To configure a Convert::Binary::C object, you can either call the configure method or directly pass the configuration options to the constructor. Automatic configuration using ccconfig As there are over 20 different configuration options, setting all of them correctly can be a lengthy and tedious task. Standard Types These are trivial. Basic Types Basic types, or atomic types, are int or char , for example.
Member Expressions This is by far the most complex part, depending on the complexity of your data structures. Offsets Members returned by the member method have an optional offset suffix to indicate that the given offset doesn't point to the start of that member. The Format Tag One of the tags currently available is the Format tag.