Recent changes to Bitfields

Bitfields modified by Will Pittenger

Will Pittenger — Fri, 14 Feb 2014 05:26:52 -0000

--- v5
+++ v6
@@ -17,7 +17,7 @@
     ~ ' Add this to the end to cause the compiler to pad the bitfield out to use whole words
 ~~~~

-With the first declaration, you access the fields inside it using identifier.field.  However, fields inside MyStruct2 can be access directly.
+With the first declaration, you access the fields inside it using identifier.field.  However, fields inside MyStruct2 can be accessed directly.

 ~~~~
 :::text

Bitfields modified by Will Pittenger

Will Pittenger — Fri, 14 Feb 2014 05:25:43 -0000

--- v4
+++ v5
@@ -1,11 +1,29 @@
-ASIL's version of the old fashioned C bitfield are fairly simple.  A bitfield in ASIL can be a member of any structure, but not a class.  They're a variation of the type-less named structs discussed in [Nested type-less named structs].  However, bitfields don't have an identifier for the bitfield itself.
+ASIL's version of the old fashioned C bitfield are fairly simple.  A bitfield in ASIL can be a member of any structure, but not a class.  They're a variation of the type-less named structs discussed in [Nested type-less named structs].  However, many bitfields don't need an identifier for the bitfield itself.

 Bitfields start with the **[bitfield](keywords-bitfield)** keyword.    Each member is either an unsigned integer or a boolean.  Each field uses the syntax (public|protected|private) var length% \[boolean\] identifier where length% is the number of bits needed for that field.  If the "boolean" portion is present, the field is a boolean.  Otherwise, the field is an unsigned int based on the word type.

 ~~~~
-struct MyStruct
+:::text
+struct MyStruct1
+  bitfield identifier
+    public 1 boolean bMyBool ' A boolean that's just a single bit long
+    public 3 iMyInt ' An unsigned integer 3 bits long
+    ~ ' Add this to the end to cause the compiler to pad the bitfield out to use whole words
+    
+struct MyStruct2
   bitfield
     public 1 boolean bMyBool ' A boolean that's just a single bit long
     public 3 iMyInt ' An unsigned integer 3 bits long
     ~ ' Add this to the end to cause the compiler to pad the bitfield out to use whole words
 ~~~~
+
+With the first declaration, you access the fields inside it using identifier.field.  However, fields inside MyStruct2 can be access directly.
+
+~~~~
+:::text
+var MyStruct1 firstInstance = new MyStruct1
+var MyStruct2 secondInstance = new MyStruct2
+
+firstInstance.identifier.bMyBool = false
+secondInstance.bMyBool = true
+~~~~

Bitfields modified by Will Pittenger

Will Pittenger — Fri, 14 Feb 2014 05:09:57 -0000

--- v3
+++ v4
@@ -1,6 +1,6 @@
 ASIL's version of the old fashioned C bitfield are fairly simple.  A bitfield in ASIL can be a member of any structure, but not a class.  They're a variation of the type-less named structs discussed in [Nested type-less named structs].  However, bitfields don't have an identifier for the bitfield itself.

-Bitfields start with the [**bitfield**] keyword.    Each member is either an unsigned integer or a boolean.  Each field uses the syntax (public|protected|private) var length% \[boolean\] identifier where length% is the number of bits needed for that field.  If the "boolean" portion is present, the field is a boolean.  Otherwise, the field is an unsigned int based on the word type.
+Bitfields start with the **[bitfield](keywords-bitfield)** keyword.    Each member is either an unsigned integer or a boolean.  Each field uses the syntax (public|protected|private) var length% \[boolean\] identifier where length% is the number of bits needed for that field.  If the "boolean" portion is present, the field is a boolean.  Otherwise, the field is an unsigned int based on the word type.

 ~~~~
 struct MyStruct

Discussion for Bitfields page

Will Pittenger — Sun, 09 Feb 2014 11:57:32 -0000

Should bitfields allow signed fields? I could use feedback here. The problem is the number of different ways to represent a signed integer.

Bitfields modified by Will Pittenger

Will Pittenger — Sun, 09 Feb 2014 07:56:22 -0000

--- v2
+++ v3
@@ -1,4 +1,4 @@
-ASIL's version of the old fashioned C bitfield are fairly simple.  A bitfield in ASIL can be a member of any structure, but not a class.  They're a variation of the type-less named structs discussed in [[Nested type-less named structs]].  However, bitfields don't have an identifier for the bitfield itself.
+ASIL's version of the old fashioned C bitfield are fairly simple.  A bitfield in ASIL can be a member of any structure, but not a class.  They're a variation of the type-less named structs discussed in [Nested type-less named structs].  However, bitfields don't have an identifier for the bitfield itself.

 Bitfields start with the [**bitfield**] keyword.    Each member is either an unsigned integer or a boolean.  Each field uses the syntax (public|protected|private) var length% \[boolean\] identifier where length% is the number of bits needed for that field.  If the "boolean" portion is present, the field is a boolean.  Otherwise, the field is an unsigned int based on the word type.

Bitfields modified by Will Pittenger

Will Pittenger — Sun, 09 Feb 2014 07:55:00 -0000

--- v1
+++ v2
@@ -1,4 +1,4 @@
-ASIL's version of the old fashioned C bitfield are fairly simple.  A bitfield in ASIL can be a member of any structure, but not a class.  They're a variation of the type-less named structs discussed in [Type-less named structures].  However, bitfields don't have an identifier for the bitfield itself.
+ASIL's version of the old fashioned C bitfield are fairly simple.  A bitfield in ASIL can be a member of any structure, but not a class.  They're a variation of the type-less named structs discussed in [[Nested type-less named structs]].  However, bitfields don't have an identifier for the bitfield itself.

 Bitfields start with the [**bitfield**] keyword.    Each member is either an unsigned integer or a boolean.  Each field uses the syntax (public|protected|private) var length% \[boolean\] identifier where length% is the number of bits needed for that field.  If the "boolean" portion is present, the field is a boolean.  Otherwise, the field is an unsigned int based on the word type.

Bitfields modified by Will Pittenger

Will Pittenger — Sun, 09 Feb 2014 07:52:58 -0000

ASIL's version of the old fashioned C bitfield are fairly simple. A bitfield in ASIL can be a member of any structure, but not a class. They're a variation of the type-less named structs discussed in [Type-less named structures]. However, bitfields don't have an identifier for the bitfield itself.

Bitfields start with the [bitfield] keyword. Each member is either an unsigned integer or a boolean. Each field uses the syntax (public|protected|private) var length% [boolean] identifier where length% is the number of bits needed for that field. If the "boolean" portion is present, the field is a boolean. Otherwise, the field is an unsigned int based on the word type.

struct MyStruct
  bitfield
    public 1 boolean bMyBool ' A boolean that's just a single bit long
    public 3 iMyInt ' An unsigned integer 3 bits long
    ~ ' Add this to the end to cause the compiler to pad the bitfield out to use whole words