Zilog ZUSBOPTS - Manual (Page 195)

UM017105-0511 Language Extensions
Zilog Developer Studio II – ZNEO™
User Manual
167
Inline Assembly Using the Pragma Directive
The first method uses the #pragma feature of ANSI C with the following syntax:
#pragma asm “ <assembly line> ”
#pragma can be inserted anywhere within the C source file. The contents of
<assembly line> must be legal assembly language syntax. The usual C escape sequences
(such as
\n , \t , and \r ) are properly translated. Currently, the compiler does not process
the <assembly line>. Except for escape sequences, it is passed through the compiler verba-
tim.
Inline Assembly Using the asm Statement
The second method of inserting assembly language uses the asm statement:
asm( “ <assembly line> ” );
The asm statement cannot be within an expression and can be used only within the body of
a function.
The <assembly line> can be any string.The compiler does not check the legality of the
string.
As with the #pragma asm form, the compiler does not process the <assembly line>
except for translating the standard C escape sequences.
The compiler prefixes the name of every global variable name with "_". Global variables
can therefore be accessed in inline assembly by prefixing their name with "_ ". The local
variables and parameters cannot be accessed in inline assembly.
Char and Short Enumerations
The enumeration data type is defined as int as per ANSI C. The C-Compiler provides
language extensions to specify the enumeration data type to be other than int to save
space. The following syntax is provided by the C-Compiler to declare them as char or
short :
enum
{
RED = 0,
YELLOW,
BLUE,
INVALID
} char color;
enum
{
NEW= 0,
OPEN,