SWMM5 macros.h Summary

 The macros.h file defines several commonly used macros in the SWMM5 project to simplify and optimize code. These macros are used for error checking, memory management, mathematical operations, and function calls. Here's a breakdown of each section:

Key Macros:

Memory Management:

1. MEMCHECK(x):

   • Checks whether a pointer x is NULL. If x is NULL, it returns 101, otherwise 0. This is useful for checking if memory allocation was successful.

2. FREE(x):

   • Frees a pointer x if it is not NULL, and sets it to NULL afterward. This is a safe way to deallocate memory.

Mathematical Operations:

3. ABS(x):

   • Computes the absolute value of x. If x is negative, it returns -x; otherwise, it returns x.

4. MIN(x, y):

   • Returns the minimum of x and y.

5. MAX(x, y):

   • Returns the maximum of x and y.

6. MOD(x, y):

   • Computes the modulus of x by y (i.e., x % y).

7. LOG10(x):

   • Computes the base-10 logarithm of x. It checks if x is greater than 0.0 before applying log10(), otherwise, it returns x unchanged. This ensures that the logarithm is only calculated for positive values.

8. SQR(x):

   • Computes the square of x (i.e., x * x).

9. SGN(x):

   • Returns the sign of x: -1 for negative x, 1 for positive x, and 0 for x equal to 0.

10. SIGN(x, y):

    • Returns the absolute value of x if y is non-negative, or the negative absolute value of x if y is negative. This macro is useful for computing values that depend on the sign of a second variable.

11. UCHAR(x):

    • Converts a lowercase character x to uppercase if it's a letter between a and z. If x is not a lowercase letter, it returns x unchanged.

12. ARRAY_LENGTH(x):

    • Computes the length of an array x by dividing the total size of the array by the size of its first element. This is useful for determining the number of elements in a statically allocated array.

Error Checking:

13. CALL(x):
    • Executes the function or expression x, but only if ErrorCode is not positive (i.e., ErrorCode is 0 or a negative value). If ErrorCode is positive, it prevents the execution of x. This is useful for error handling, ensuring that subsequent operations are only performed if no errors have occurred.

Summary:

The macros.h file defines a set of utility macros for handling memory, mathematical operations, and error checking. These macros help improve code readability, reduce redundancy, and ensure safe memory management and error handling throughout the SWMM5 project.