@end example
The type definition of argv is interesting because it defines two new
-types in terms of an existing one. The array argv contains character
-pointers. The type of the array name is a pointer to the type the
-array holds. Thus the type of argv is ptr to ptr to char. The stab
-for argv contains nested type_definitions. Type 21 is ptr to type 2
-(char) and argv (type 20) is ptr to type 21.
+types in terms of an existing one. The ``array'' argv is really a
+pointer, according to C language rules, since it is declared as a
+parameter. Its element type is character pointers. Thus the type of
+argv is ptr to ptr to char. The stab for argv contains nested
+type_definitions. Type 21 is ptr to type 2 (char) and argv (type 20)
+is ptr to type 21.
@node Aggregate Types
@chapter Aggregate Types
@item Symbol Descriptor:
@code{T}
@item Type Descriptor:
-@code{ar}
+@code{a}
@end table
As an example of an array type consider the global variable below.
G is a definition for type (19) as shown by the equals sign after the
type number.
-After the equals sign is a type descriptor, ar, which says that the
-type being defined is an array. Following the type descriptor for an
-array is the type of the index, the lower bound for array indexing
-(always 0 in C), the upper bound for array indexing (in C: one less
-than the length of the array), and the type of the array elements.
+After the equals sign is a type descriptor, a, which says that the type
+being defined is an array. Following the type descriptor for an array
+is the type of the index, a semicolon, and the type of the array elements.
+
+The type of the index is often a range type, expressed as the letter r
+and some parameters. It defines the size of the array. In in the
+example below, the range @code{r1;0;2;} defines an index type which is
+a subrange of type 1 (integer), with a lower bound of 0 and an upper
+bound of 2. This defines the valid range of subscripts of a
+three-element C array.
The array definition above generates the assembly language that
follows.
@example
@exdent <32> N_GSYM - global variable
@exdent .stabs "name:sym_desc(global)type_def(19)=type_desc(array)
-@exdent index_type_ref(int);NIL;high_bound(2);element_type_ref(char)";
+@exdent index_type_ref(range of int from 0 to 2);element_type_ref(char)";
@exdent N_GSYM, NIL, NIL, NIL
32 .stabs "char_vec:G19=ar1;0;2;2",32,0,0,0
struct_bytes
elem_name:type_ref(int),bit_offset,field_bits;
elem_name:type_ref(float),bit_offset,field_bits;
- elem_name:type_def(17)=type_desc(dynamic array) index_type(int);NIL;
- high_bound(7);element_type(char),bit_offset,field_bits;;",
+ elem_name:type_def(17)=type_desc(array)
+ index_type(range of int from 0 to 7);
+ element_type(char),bit_offset,field_bits;;",
N_LSYM,NIL,NIL,NIL
30 .stabs "s_tag:T16=s20s_int:1,0,32;s_float:12,32,32;
This is in turn defined as a pointer to another new type (22).
Type 22 is the vtable itself, which is defined as an array, indexed by
-integers, with a high bound of 1, and elements of type 17. Type 17
-was the vtable record type defined by the boilerplate C++ type
-definitions, as shown earlier.
+a range of integers between 0 and 1, and whose elements are of type
+17. Type 17 was the vtable record type defined by the boilerplate C++
+type definitions, as shown earlier.
The bit offset of the vtable pointer field is 32. The number of bits
in the field are not specified when the field is a vtable pointer.
.stabs "class_name(A):type_def(20)=sym_desc(struct)struct_bytes(8)
field_name(Adat):type_ref(int),bit_offset(0),field_bits(32);
field_name(A virt func ptr):type_def(21)=type_desc(ptr to)type_def(22)=
- sym_desc(array)index_type_ref(int);NIL;elem_type_ref(vtbl elem type);
+ sym_desc(array)index_type_ref(range of int from 0 to 1);
+ elem_type_ref(vtbl elem type),
bit_offset(32);
meth_name(A_virt)::typedef(23)=sym_desc(method)returning(int);
:arg_type(int),protection(public)normal(yes)virtual(yes)
# -> p (value parameter)
-> i (value parameter by reference, indirect access)
-> v (variable parameter by reference)
- -> C ( read-only parameter, conformant array bound)
- -> x (confomant array value parameter)
+ -> C (read-only parameter, conformant array bound)
+ -> x (conformant array value parameter)
-> pP (<<??>>)
-> pF (<<??>>)
-> X (function result variable)
N_LSYM. Sun doc talks about using N_GSYM too.
@item
-@c FIXME: are you sure? The 'a' is usually followed by an 'r' which means
-@c "range type" but that doesn't mean the type descriptor is 'ar'.
-@c A (non-C) array could be indexed by an enum, for example. -kingdon
-GNU C stabs use `ar' as type descriptor when defining arrays vs. just
-`a' in Sun doc.
-
-@item
Stabs describing block scopes, N_LBRAC and N_RBRAC are supposed to
contain the nesting level of the block in the desc field, re Sun doc.
GNU stabs always have 0 in that field.
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