C allows a structure or union variable to have the same name as the type name, but MASM does not. The H2INC /Zu option prevents the structure name from matching a variable or instance by prefixing every MASM structure name with @tag_.H2INC translates C structures and unions into their MASM equivalents. H2INC modifies the C structure or union definition to account for differences from MASM structure and union definitions. This list describes these modifications.
C allows a structure or union variable to have the same name as the type name, but MASM does not. The H2INC /Zu option prevents the structure name from matching a variable or instance by prefixing every MASM structure name with @tag_.
If a C structure or union definition does not have a name, H2INC supplies one for the MASM conversion. These generated structure names take the form @tag_n, where n is an integer that starts at zero and is incremented for each structure name H2INC generates.
If the /Zn option is specified, H2INC inserts the given string between the underscore and the number in the generated structure names. This eliminates name conflicts with other H2INC-generated include files.
H2INC adds the alignment value to the converted structure definition.
The following examples show how these rules are applied when converting structures. (Union conversions are not shown; they are handled identically.) These examples assume that the C header file defines an alignment value of 2. (See Section 5.2.1, “Declaring Structure and Union Types,” for information on alignment values.)
The following named C structure definition
struct file_info
{
unsigned char file_addr;
unsigned int file_size;
};
is converted to the following MASM form. Except for explicitly specifying the alignment value, the conversion is direct:
file_info STRUCT 2t
file_addr BYTE ?
file_size WORD ?
file_info ENDS
If the same C structure definition is converted using the /Zu option, the @tag_ prefix is added to the structure's name so that the name does not duplicate the name of a structure component:
@tag_file_info STRUCT 2t
file_addr BYTE ?
file_size WORD ?
@tag_file_info ENDS
If the original C structure definition is modified to be an unnamed-type declaration of a specific instance (myfile)
struct
{
unsigned char file_addr;
unsigned int file_size;
} myfile ;
its MASM conversion looks like the following example. (The specific integer added to the @tag_ prefix is determined by the sequence in which H2INC creates tag names.)
@tag_7 STRUCT 2t
file_addr BYTE ?
file_size WORD ?
@tag_7 ENDS
EXTERNDEF C myfile:@tag_7
Nested structures may have as many levels as desired; they are not limited to one level. Nested structures are “unnested” (expanded) in the correct hierarchical sequence, as shown with the C structure and H2INC-generated code in this example.
/* C code: */
struct phone
{
int areacode;
long number;
};
struct person
{
char name[30];
char sex;
int age;
int weight;
struct phone;
} Jim;
; H2INC generated code:
phone STRUCT 2t
areacode SWORD ?
number SDWORD ?
phone ENDS
person STRUCT 2t
name SBYTE 30t DUP (?)
sex SBYTE ?
age SWORD ?
weight SWORD ?
STRUCT
areacode SWORD ?
number SDWORD ?
ENDS
person ENDS
EXTERNDEF C Jim:person
See Section 5.2 for information on MASM structures and unions.