X-Git-Url: https://gitweb.factorcode.org/gitweb.cgi?p=factor.git;a=blobdiff_plain;f=basis%2Falien%2Fc-types%2Fc-types-docs.factor;h=c425d290edcc173bbcc4ec40f40e5f58043899aa;hp=390477dcac738a4646efd5089002544f04c95339;hb=98e31346d3ddd0f54d622e6ec489bdb48e090355;hpb=0836e79e6654fc48a81d089d783cc2a623535316 diff --git a/basis/alien/c-types/c-types-docs.factor b/basis/alien/c-types/c-types-docs.factor old mode 100755 new mode 100644 index 390477dcac..c425d290ed --- a/basis/alien/c-types/c-types-docs.factor +++ b/basis/alien/c-types/c-types-docs.factor @@ -1,79 +1,38 @@ -USING: alien alien.complex help.syntax help.markup libc kernel.private -byte-arrays strings hashtables alien.syntax alien.strings sequences -io.encodings.string debugger destructors vocabs.loader -classes.struct ; -QUALIFIED: math +USING: alien alien.syntax byte-arrays classes.struct help.markup +help.syntax kernel math sequences ; IN: alien.c-types -HELP: byte-length -{ $values { "seq" "A byte array or float array" } { "n" "a non-negative integer" } } -{ $contract "Outputs the size of the byte array, struct, or specialized array data in bytes." } ; - HELP: heap-size -{ $values { "type" string } { "size" math:integer } } +{ $values { "name" c-type-name } { "size" math:integer } } { $description "Outputs the number of bytes needed for a heap-allocated value of this C type." } { $examples - "On a 32-bit system, you will get the following output:" - { $unchecked-example "USE: alien\n\"void*\" heap-size ." "4" } + { $example "USING: alien alien.c-types prettyprint ;\nint heap-size ." "4" } } { $errors "Throws a " { $link no-c-type } " error if the type does not exist." } ; -HELP: stack-size -{ $values { "type" string } { "size" math:integer } } -{ $description "Outputs the number of bytes to reserve on the C stack by a value of this C type. In most cases this is equal to " { $link heap-size } ", except on some platforms where C structs are passed by invisible reference, in which case a C struct type only uses as much space as a pointer on the C stack." } -{ $errors "Throws a " { $link no-c-type } " error if the type does not exist." } ; - HELP: -{ $values { "type" hashtable } } +{ $values { "c-type" c-type } } { $description "Creates a prototypical C type. User code should use higher-level facilities to define C types; see " { $link "c-data" } "." } ; HELP: no-c-type -{ $values { "type" string } } +{ $values { "name" c-type-name } } { $description "Throws a " { $link no-c-type } " error." } -{ $error-description "Thrown by " { $link c-type } " if a given string does not name a C type. When thrown during compile time, indicates a typo in an " { $link alien-invoke } " or " { $link alien-callback } " form." } ; - -HELP: c-types -{ $var-description "Global variable holding a hashtable mapping C type names to C types. Use the " { $link c-type } " word to look up C types." } ; +{ $error-description "Thrown by " { $link c-type } " if a given word is not a C type." } ; -HELP: c-type -{ $values { "name" string } { "type" hashtable } } +HELP: lookup-c-type +{ $values { "name" c-type-name } { "c-type" c-type } } { $description "Looks up a C type by name." } -{ $errors "Throws a " { $link no-c-type } " error if the type does not exist." } ; +{ $errors "Throws a " { $link no-c-type } " error if the type does not exist, or the word is not a C type." } ; -HELP: c-getter -{ $values { "name" string } { "quot" { $quotation "( c-ptr n -- obj )" } } } -{ $description "Outputs a quotation which reads values of this C type from a C structure." } +HELP: alien-value +{ $values { "c-ptr" c-ptr } { "offset" integer } { "c-type" c-type-name } { "value" object } } +{ $description "Loads a value at a byte offset from a base C pointer." } { $errors "Throws a " { $link no-c-type } " error if the type does not exist." } ; -HELP: c-setter -{ $values { "name" string } { "quot" { $quotation "( obj c-ptr n -- )" } } } -{ $description "Outputs a quotation which writes values of this C type to a C structure." } -{ $errors "Throws an error if the type does not exist." } ; - -HELP: box-parameter -{ $values { "n" math:integer } { "ctype" string } } -{ $description "Generates code for converting a C value stored at offset " { $snippet "n" } " from the top of the stack into a Factor object to be pushed on the data stack." } -{ $notes "This is an internal word used by the compiler when compiling callbacks." } ; - -HELP: box-return -{ $values { "ctype" string } } -{ $description "Generates code for converting a C value stored in return registers into a Factor object to be pushed on the data stack." } -{ $notes "This is an internal word used by the compiler when compiling alien calls." } ; - -HELP: unbox-return -{ $values { "ctype" string } } -{ $description "Generates code for converting a Factor value on the data stack into a C value to be stored in the return registers." } -{ $notes "This is an internal word used by the compiler when compiling callbacks." } ; - -HELP: define-deref -{ $values { "name" "a word name" } } -{ $description "Defines a word " { $snippet "*name" } " with stack effect " { $snippet "( c-ptr -- value )" } " for reading a value with C type " { $snippet "name" } " stored at an alien pointer." } -{ $notes "This is an internal word called when defining C types, there is no need to call it on your own." } ; - -HELP: define-out -{ $values { "name" "a word name" } } -{ $description "Defines a word " { $snippet "<" { $emphasis "name" } ">" } " with stack effect " { $snippet "( value -- array )" } ". This word allocates a byte array large enough to hold a value with C type " { $snippet "name" } ", and writes the value at the top of the stack to the array." } -{ $notes "This is an internal word called when defining C types, there is no need to call it on your own." } ; +HELP: set-alien-value +{ $values { "value" object } { "c-ptr" c-ptr } { "offset" integer } { "c-type" c-type-name } } +{ $description "Stores a value at a byte offset from a base C pointer." } +{ $errors "Throws a " { $link no-c-type } " error if the type does not exist." } ; HELP: char { $description "This C type represents a one-byte signed integer type. Input values will be converted to " { $link math:integer } "s and truncated to eight bits; output values will be returned as " { $link math:fixnum } "s." } ; @@ -89,27 +48,44 @@ HELP: uint { $description "This C type represents a four-byte unsigned integer type. Input values will be converted to " { $link math:integer } "s and truncated to 32 bits; output values will be returned as " { $link math:integer } "s." } ; HELP: long { $description "This C type represents a four- or eight-byte signed integer type. On Windows and on 32-bit Unix platforms, it will be four bytes. On 64-bit Unix platforms, it will be eight bytes. Input values will be converted to " { $link math:integer } "s and truncated to 32 or 64 bits; output values will be returned as " { $link math:integer } "s." } ; +HELP: intptr_t +{ $description "This C type represents a signed integer type large enough to hold any pointer value; that is, on 32-bit platforms, it will be four bytes, and on 64-bit platforms, it will be eight bytes. Input values will be converted to " { $link math:integer } "s and truncated to 32 or 64 bits; output values will be returned as " { $link math:integer } "s." } ; HELP: ulong { $description "This C type represents a four- or eight-byte unsigned integer type. On Windows and on 32-bit Unix platforms, it will be four bytes. On 64-bit Unix platforms, it will be eight bytes. Input values will be converted to " { $link math:integer } "s and truncated to 32 or 64 bits; output values will be returned as " { $link math:integer } "s." } ; +HELP: uintptr_t +{ $description "This C type represents an unsigned integer type large enough to hold any pointer value; that is, on 32-bit platforms, it will be four bytes, and on 64-bit platforms, it will be eight bytes. Input values will be converted to " { $link math:integer } "s and truncated to 32 or 64 bits; output values will be returned as " { $link math:integer } "s." } ; +HELP: ptrdiff_t +{ $description "This C type represents a signed integer type large enough to hold the distance between two pointer values; that is, on 32-bit platforms, it will be four bytes, and on 64-bit platforms, it will be eight bytes. Input values will be converted to " { $link math:integer } "s and truncated to 32 or 64 bits; output values will be returned as " { $link math:integer } "s." } ; +HELP: size_t +{ $description "This C type represents unsigned size values of the size expected by the platform's standard C library (usually four bytes on a 32-bit platform, and eight on a 64-bit platform). Input values will be converted to " { $link math:integer } "s and truncated to the appropriate size; output values will be returned as " { $link math:integer } "s." } ; HELP: longlong { $description "This C type represents an eight-byte signed integer type. Input values will be converted to " { $link math:integer } "s and truncated to 64 bits; output values will be returned as " { $link math:integer } "s." } ; HELP: ulonglong { $description "This C type represents an eight-byte unsigned integer type. Input values will be converted to " { $link math:integer } "s and truncated to 64 bits; output values will be returned as " { $link math:integer } "s." } ; HELP: void -{ $description "This symbol is not a valid C type, but it can be used as the return type for a " { $link POSTPONE: FUNCTION: } " or " { $link POSTPONE: CALLBACK: } " definition, or an " { $link alien-invoke } " or " { $link alien-callback } " call." } ; +{ $description "This symbol is not a valid C type, but it can be used as the return type for a " { $link POSTPONE: FUNCTION: } " or " { $link POSTPONE: CALLBACK: } " definition or for an " { $link alien-invoke } " or " { $link alien-callback } " call." } ; HELP: void* -{ $description "This C type represents a pointer to C memory. " { $link byte-array } " and " { $link alien } " values can be passed as inputs, but see " { $link "byte-arrays-gc" } " for notes about passing byte arrays into C functions. Output values are returned as " { $link alien } "s." } ; -HELP: char* +{ $description "This C type represents a generic pointer to C memory. See " { $link pointer } " for information on pointer C types." } ; +HELP: c-string { $description "This C type represents a pointer to a C string. See " { $link "c-strings" } " for details about using strings with the FFI." } ; HELP: float { $description "This C type represents a single-precision IEEE 754 floating-point type. Input values will be converted to Factor " { $link math:float } "s and demoted to single-precision; output values will be returned as Factor " { $link math:float } "s." } ; HELP: double { $description "This C type represents a double-precision IEEE 754 floating-point type. Input values will be converted to Factor " { $link math:float } "s; output values will be returned as Factor " { $link math:float } "s." } ; -HELP: complex-float -{ $description "This C type represents a single-precision IEEE 754 floating-point complex type. Input values will be converted from Factor " { $link math:complex } " objects into a single-precision complex float type; output values will be returned as Factor " { $link math:complex } " objects." } ; -HELP: complex-double -{ $description "This C type represents a double-precision IEEE 754 floating-point complex type. Input values will be converted from Factor " { $link math:complex } " objects into a double-precision complex float type; output values will be returned as Factor " { $link math:complex } " objects." } ; +HELP: pointer: +{ $syntax "pointer: c-type" } +{ $description "Constructs a " { $link pointer } " C type." } ; + +HELP: pointer +{ $class-description "Represents a pointer C type. The " { $snippet "to" } " slot contains the C type being pointed to. Both " { $link byte-array } " and " { $link alien } " values can be provided as pointer function inputs, but see " { $link "byte-arrays-gc" } " for notes about passing byte arrays into C functions. Objects with methods on " { $link >c-ptr } ", such as structs and specialized arrays, may also be used as pointer inputs." +$nl +"Pointer output values are represented in Factor as " { $link alien } "s. If the pointed-to type is a struct, the alien will automatically be wrapped in a struct object if it is not null." +$nl +"In " { $link POSTPONE: TYPEDEF: } ", " { $link POSTPONE: FUNCTION: } ", " { $link POSTPONE: CALLBACK: } ", and " { $link POSTPONE: STRUCT: } " definitions, pointer types can be created by suffixing " { $snippet "*" } " to a C type name. Outside of FFI definitions, a pointer C type can be created using the " { $link POSTPONE: pointer: } " syntax word:" +{ $unchecked-example "FUNCTION: int* foo ( char* bar )" } +{ $unchecked-example ": foo ( bar -- int* ) + pointer: int f \"foo\" { pointer: char } f alien-invoke ;" } } ; ARTICLE: "byte-arrays-gc" "Byte arrays and the garbage collector" "The Factor garbage collector can move byte arrays around, and it is only safe to pass byte arrays to C functions if the garbage collector will not run while C code still has a reference to the data." @@ -124,45 +100,10 @@ $nl "If this condition is not satisfied, " { $link "malloc" } " must be used instead." { $warning "Failure to comply with these requirements can lead to crashes, data corruption, and security exploits." } ; -ARTICLE: "c-out-params" "Output parameters in C" -"A frequently-occurring idiom in C code is the \"out parameter\". If a C function returns more than one value, the caller passes pointers of the correct type, and the C function writes its return values to those locations." -$nl -"Each numerical C type, together with " { $snippet "void*" } ", has an associated " { $emphasis "out parameter constructor" } " word which takes a Factor object as input, constructs a byte array of the correct size, and converts the Factor object to a C value stored into the byte array:" -{ $subsection } -{ $subsection } -{ $subsection } -{ $subsection } -{ $subsection } -{ $subsection } -{ $subsection } -{ $subsection } -{ $subsection } -{ $subsection } -{ $subsection } -{ $subsection } -{ $subsection } -"You call the out parameter constructor with the required initial value, then pass the byte array to the C function, which receives a pointer to the start of the byte array's data area. The C function then returns, leaving the result in the byte array; you read it back using the next set of words:" -{ $subsection *char } -{ $subsection *uchar } -{ $subsection *short } -{ $subsection *ushort } -{ $subsection *int } -{ $subsection *uint } -{ $subsection *long } -{ $subsection *ulong } -{ $subsection *longlong } -{ $subsection *ulonglong } -{ $subsection *float } -{ $subsection *double } -{ $subsection *void* } -"Note that while structure and union types do not get these words defined for them, there is no loss of generality since " { $link } " and " { $link *void* } " may be used." ; - -ARTICLE: "c-types-specs" "C type specifiers" -"C types are identified by special words, and type names occur as parameters to the " { $link alien-invoke } ", " { $link alien-indirect } " and " { $link alien-callback } " words. New C types can be defined by the words " { $link POSTPONE: STRUCT: } ", " { $link POSTPONE: UNION-STRUCT: } ", " { $link POSTPONE: CALLBACK: } ", and " { $link POSTPONE: TYPEDEF: } "." -$nl -"The following numerical types are available; a " { $snippet "u" } " prefix denotes an unsigned type:" +ARTICLE: "c-types.primitives" "Primitive C types" +"The following numerical types are defined in the " { $vocab-link "alien.c-types" } " vocabulary; a " { $snippet "u" } " prefix denotes an unsigned type:" { $table - { "C type" "Notes" } + { { $strong "C type" } { $strong "Notes" } } { { $link char } "always 1 byte" } { { $link uchar } { } } { { $link short } "always 2 bytes" } @@ -175,15 +116,66 @@ $nl { { $link ulonglong } { } } { { $link float } { "single-precision float (not the same as Factor's " { $link math:float } " class!)" } } { { $link double } { "double-precision float (the same format as Factor's " { $link math:float } " objects)" } } - { { $link complex-float } { "C99 or Fortran " { $snippet "complex float" } " type, converted to and from Factor " { $link math:complex } " values" } } - { { $link complex-double } { "C99 or Fortran " { $snippet "complex double" } " type, converted to and from Factor " { $link math:complex } " values" } } } -"When making alien calls, Factor numbers are converted to and from the above types in a canonical way. Converting a Factor number to a C value may result in a loss of precision." +"C99 complex number types are defined in the " { $vocab-link "alien.complex" } " vocabulary." $nl -"Pointer types are specified by suffixing a C type with " { $snippet "*" } ", for example " { $snippet "float*" } ". One special case is " { $link void* } ", which denotes a generic pointer; " { $link void } " by itself is not a valid C type specifier. With the exception of strings (see " { $link "c-strings" } "), all pointer types are identical to " { $snippet "void*" } " as far as the C library interface is concerned." +"When making alien calls, Factor numbers are converted to and from the above types in a canonical way. Converting a Factor number to a C value may result in a loss of precision." ; + +ARTICLE: "c-types.pointers" "Pointer and array types" +"Pointer types are specified by suffixing a C type with " { $snippet "*" } ", for example " { $snippet "float*" } ". One special case is " { $link void* } ", which denotes a generic pointer; " { $link void } " by itself is not a valid C type specifier. This syntax constructs a " { $link pointer } " object to represent the C type." $nl "Fixed-size array types are supported; the syntax consists of a C type name followed by dimension sizes in brackets; the following denotes a 3 by 4 array of integers:" { $code "int[3][4]" } -"Fixed-size arrays differ from pointers in that they are allocated inside structures and unions; however when used as function parameters they behave exactly like pointers and thus the dimensions only serve as documentation." +"Fixed-size arrays differ from pointers in that they are allocated inside structures and unions; however, when used as function parameters, they behave exactly like pointers with the dimensions only serving as documentation." ; + +ARTICLE: "c-types.ambiguity" "Word name clashes with C types" +"Note that some of the C type word names clash with commonly-used Factor words:" +{ $list + { { $link float } " clashes with the " { $link math:float } " word in the " { $vocab-link "math" } " vocabulary" } +} +"If you use the wrong vocabulary, you will see a " { $link no-c-type } " error. For example, the following is " { $strong "not" } " valid, and will raise an error because the " { $link math:float } " word from the " { $vocab-link "math" } " vocabulary is not a C type:" +{ $code + "USING: alien.syntax math prettyprint ;" + "FUNCTION: float magic_number ( )" + "magic_number 3.0 + ." +} +"The following won't work either; now the problem is that there are two vocabularies in the search path that define a word named " { $snippet "float" } ":" +{ $code + "USING: alien.c-types alien.syntax math prettyprint ;" + "FUNCTION: float magic_number ( )" + "magic_number 3.0 + ." +} +"The correct solution is to use one of " { $link POSTPONE: FROM: } ", " { $link POSTPONE: QUALIFIED: } " or " { $link POSTPONE: QUALIFIED-WITH: } " to disambiguate word lookup:" +{ $code + "USING: alien.syntax math prettyprint ;" + "QUALIFIED-WITH: alien.c-types c" + "FUNCTION: c:float magic_number ( )" + "magic_number 3.0 + ." +} +"See " { $link "word-search-semantics" } " for details." ; + +ARTICLE: "c-types.structs" "Struct and union types" +"Struct and union types are identified by their class word. See " { $link "classes.struct" } "." ; + +ARTICLE: "c-types-specs" "C type specifiers" +"C types are identified by special words. Type names occur as parameters to the " { $link alien-invoke } ", " { $link alien-indirect } " and " { $link alien-callback } " words." $nl -"Structure and union types are specified by the name of the structure or union." ; +"Defining new C types:" +{ $subsections + POSTPONE: STRUCT: + POSTPONE: UNION-STRUCT: + POSTPONE: CALLBACK: + POSTPONE: TYPEDEF: +} +"Getting the c-type of a class:" +{ $subsections lookup-c-type } +{ $heading "Related articles" } +{ $subsections + "c-types.primitives" + "c-types.pointers" + "c-types.ambiguity" + "c-types.structs" +} +; + +ABOUT: "c-types-specs"