))

01: prevent a header file from being repeatedly contained

# Ifndef COMDEF_H
# Define COMDEF_H
// Header file content
# Endif

 

02: redefines some types to prevent the differences in the number of bytes of the types caused by different platforms and compilers, so as to facilitate migration.
Typedef unsigned char boolean;/* Boolean value type .*/
Typedef unsigned long int uint32;/* Unsigned 32 bit value */
Typedef unsigned short uint16;/* Unsigned 16 bit value */
Typedef unsigned char uint8;/* Unsigned 8 bit value */
Typedef signed long int int32;/* Signed 32 bit value */
Typedef signed short int16;/* Signed 16 bit value */
Typedef signed char int8;/* Signed 8 bit value */

// The following is not recommended
Typedef unsigned char byte;/* Unsigned 8 bit value type .*/
Typedef unsigned short word;/* Unsinged 16 bit value type .*/
Typedef unsigned long dword;/* Unsigned 32 bit value type .*/
Typedef unsigned char uint1;/* Unsigned 8 bit value type .*/
Typedef unsigned short uint2;/* Unsigned 16 bit value type .*/
Typedef unsigned long uint4;/* unsigned 32 bit value type .*/
Typedef signed Char int1;/* signed 8 bit value type .*/
Typedef signed short int2;/* signed 16 bit value type .*/
Typedef long int int4;/* signed 32 bit value type .*/
Typedef signed long sint31;/* signed 32 bit value */
Typedef signed short sint15;/* signed 16 bit value */
Typedef signed char sint7;/* Signed 8 bit value */

 

03: Get a byte or word on the specified address
# Define MEM_ B (x) (* (byte *) (x )))
# Define MEM_W (x) (* (word *) (x )))

 

04: calculate the maximum and minimum values
# Define MAX (x, y) (x)> (y ))? (X): (y ))
# Define MIN (x, y) (x) <(y ))? (X): (y ))

 

05: Get the offset of a field in the struct (struct ).
# Define FPOS (type, field) (dword) & (type *) 0)-> field)

 

06: Get the number of bytes occupied by field in a struct.
# Define FSIZ (type, field) sizeof (type *) 0)-> field)

 

07: convert two bytes into a Word in LSB format
# Define FLIPW (ray) (word) (ray) [0]) * 256) + (ray) [1])

 

08: convert a Word into two bytes in LSB format
# Define FLOPW (ray, val) (ray) [0] = (val)/256); (ray) [1] = (val) & 0xFF)

 

09: Get the address of a variable (word width)
# Define B _PTR (var) (byte *) (void *) & (var ))
# Define W_PTR (var) (word *) (void *) & (var ))

 

10: Get the high and low bytes of a word.
# Define WORD_LO (xxx) (byte) (word) (xxx) & 255 ))
# Define WORD_HI (xxx) (byte) (word) (xxx)> 8 ))

 

11: returns a multiple of 8 nearest to X.
# Define RND8 (x) + 7)/8) * 8)

 

12: convert a letter to uppercase
# Define UPCASE (c)> = 'A' & (c) <= 'Z ')? (C)-0x20): (c ))

 

13: determines whether the character is a decimal number.
# Define DECCHK (c)> = '0' & (c) <= '9 ')

 

14: determines whether the character is a hexadecimal number.
# Define HEXCHK (c)> = '0' & (c) <= '9') (c)> = 'A' & (c) <= 'F ')/
(C)> = 'A' & (c) <= 'F '))

 

15: A method to prevent overflow
# Define INC_SAT (val) (val = (val) + 1> (val ))? (Val) + 1: (val ))

 

16: returns the number of array elements.
# Define ARR_SIZE (a) (sizeof (a)/sizeof (a [0])

 

17: return the value of N at the end of an unsigned number.Mod_by_power_of_two (x, n) = x % (2 ^ N)
# Define mod_by_power_of_two (Val, mod_by) (DWORD) (VAL )&
(DWORD) (mod_by)-1 ))

 

18: For Io space ing in the bucket structure, Input/Output Processing
# Define Indium (port) (* (volatile byte *) (port )))
# Define inpw (port) (* (volatile word *) (port )))
# Define inpdw (port) (* (volatile DWORD *) (port )))
# Define outp (port, Val) (* (volatile byte *) (port) = (byte) (VAL )))
# Define outpw (port, Val) (* (volatile word *) (port) = (Word) (VAL )))
# Define outpdw (port, Val) (* (volatile DWORD *) (port) = (DWORD) (VAL )))

 

19: use some macro tracking for debugging
The ANSI standard specifies five predefined macro names. They are:
_ Line __
_ File __
_ Date __
_ Time __
_ Stdc __
C ++ also defines _ cplusplus

If the compiler is not standard, only a few of the above macro names are supported or not supported at all. Remember that the Compilation Program may also provide other predefined macro names.

_ LINE _ and _ FILE _ macro instructions. # The line command can change its value. In short, during compilation, it contains the current number of lines and FILE names of the program.

The _ DATE _ macro command contains a string in the form of month, day, or year, which indicates the DATE when the source file was translated to the code.
The _ TIME _ macro command contains the program Compilation TIME. Time is represented by a string in the form of minute: Second
_ STDC __
Macro commands are defined during compilation. Generally, if _ STDC _ has been defined, the compiler will only accept standard C/C ++ code that does not contain any non-standard extensions. If the implementation is standard, macro _ STDC _ contains the decimal constant 1. If it contains any other number, the implementation is non-standard.
The consistent compiler of _ cplusplus and Standard c ++ defines it as a value containing at least six characters. A compiler that is inconsistent with the standard c ++ will use a value of 5 or less.

You can define macros, for example:
When _ DEBUG is defined, the output data and the row of the file
# Ifdef _ DEBUG
# Define DEBUGMSG (msg, date) printf (msg); printf ("% d", date, _ LINE _, _ FILE _)
# Else
# Define DEBUGMSG (msg, date)
# Endif

 

20: macro definition to prevent incorrect use of braces.
For example:
Definition in question: # define DUMP_WRITE (addr, nr) {memcpy (bufp, addr, nr); bufp + = nr ;}
Definition: # difne DO (a, B) do {a + B; a ++;} while (0)
For example:
If (addr)
DUMP_WRITE (addr, nr );
Else
Do_somethong_else ();
This will happen after the macro scale:
If (addr)
{Memcpy (bufp, addr, nr); bufp + = nr ;};
Else
Do_something_else ();

When gcc encounters the ";" before else, it considers that the if statement has ended, so the else following it is not in the if statement. With the do {} while (0) definition, there is no problem under any circumstances. The definition of # difne DO (a, B) do {a + B; a ++;} while (0) will not go wrong under any circumstances.