[NOTE] Porting C code to Red System

Red/System and C have roughly analogous functionality although they have very different syntax. Here are some notes about porting C/C++ to Red/System.

Types

C/C++	Red/System	Notes
char	byte!	The signedness of a C++ char can be signed or unsigned - the assumption here is signed but it varies by target system. A Red/System byte! is unsigned.
unsigned char	byte!
signed char	N/A
short int	N/A	No corresponding type in Red/System.
unsigned short int	N/A
(signed) int	integer!	In C/C++, int can be 16-bit on some old platforms (e.g DOS / Windows 3.1) 1
unsigned int	N/A	No unsigned integer! in Red/System yet.
(signed) long int	integer! or N/A	In C/C++ this is data model dependent, can be 32-bit or 64-bit 1
unsigned long int	integer! or N/A	In C/C++ this is data model dependent, can be 32-bit or 64-bit 1
(signed) long long int	N/A
unsigned long long int	N/A
size_t	N/A
float	float32!
double	float!
long double	N/A
bool	logic!

^[1] See the next section to for a discussion on data models.

Data model

The four common data models in C++ are:

• LP32 - int is 16-bit, long and pointers are 32-bit. This is an uncommon model, a throw-back to DOS / Windows 3.1
• ILP32 - int, long and pointers are 32-bit. Used by Win32, Linux, OS X
• LLP64 - int and long are 32-bit, long long and pointers are 64-bit. Used by Win64
• LP64 - int is 32-bit, long / long long and pointers are 64-bit. Used by Linux, OS X

stdint.h / cstdint

C provides a <stdint.h> header that provides unambigious typedefs with length and signedess, e.g. uint32_t. The equivalent in C++ is <cstdlib>.

C/C++	Red/System
int8_t	N/A
uint8_t	byte!
int16_t	N/A
uint16_t	N/A
uint32_t	N/A
int32_t	integer!
int64_t	N/A
uint64_t	N/A

Pointer

C/C++	Red/System
int *	int-ptr! or pointer! [integer!]
char *	byte-ptr! or pointer! [byte!] or c-string!
float *	float32-ptr! or pointer! [float32!]
double *	float-ptr! or pointer! [float!]
void *	int-ptr! or byte-ptr!

Arrays

An array is a fixed size list of elements. Only literal arrays are supported in Red/System.

E.g to create a 100 element array of double values in C++:

// Stack
int values[100];
// Heap
double *values = new double[100];
delete []values;
// Data segment
static int values[] = {1, 2, 3, 4}

And in Red/System:

// Stack
values: system/stack/allocate 100    ;@@ No need to 
// Heap
values: as float-ptr! allocate 100 * size? float!
free as byte-ptr! values
// Data segment
values: [1 2 3 4]

Example: Convert GUID to R/S array.

const IID IID_IWinHttpRequest =
{
  0x06f29373,
  0x5c5a,
  0x4b54,
  {0xb0, 0x25, 0x6e, 0xf1, 0xbf, 0x8a, 0xbf, 0x0e}
};

Convert it to Red/System.

IID_IWinHttpRequest: [06F29373h 4B545C5Ah F16E25B0h 0EBF8ABFh]