Delay Routine: Fully-portable C89 if possible

CBFalconer wrote:
> David Brown wrote:
> ... snip ...
>> I don't know what you mean by this.  If I want the smallest type
>> that holds 16-bit signed integers, I use a sint16_t - that's
>> portable, and gives me exactly what I want.
> 
> There is no such thing as a 'sint16_t', except as a non-standard
> extension in some system or other.  The following extracts are from
> N869.
> 
>   7.8  Format conversion of integer types <inttypes.h>
> 
>   [#1]  The header <inttypes.h> includes the header <stdint.h>
>   and extends it with additional facilities provided by hosted
>   implementations.
> 
>   [#2]  It  declares  four  functions  for  converting numeric
>   character strings to greatest-width integers and,  for  each
>   type declared in <stdint.h>, it defines corresponding macros
>   for  conversion  specifiers  for  use  with  the   formatted
>   input/output functions.170)
> 
>   Forward references:  integer types <stdint.h> (7.18).
> 
> and
> 
>   7.18.1.1  Exact-width integer types
> 
>   [#1] The typedef name intN_t  designates  a  signed  integer |
>   type  with  width  N.  Thus, int8_t denotes a signed integer |
>   type with a width of exactly 8 bits.
> 
>   [#2] The typedef name uintN_t designates an unsigned integer |
>   type  with  width  N.   Thus,  uint24_t  denotes an unsigned |
>   integer type with a width of exactly 24 bits.                |
> 
>   [#3]   These   types   are   optional.    However,   if   an |
>   implementation  provides integer types with widths of 8, 16, |
>   32, or 64 bits, it shall define  the  corresponding  typedef |
>   names.
> 
> Notice the above paragraph 3, stating these types are _optional_. 
> Also note that all this is not present in the C90 (or C95)
> standard.
> 
> However the thing that is universally known, and not optional, is
> that an int (and a short int) has a minimum size of 16 bits, and
> that a long has a minimum size of 32 bits.  If a compiler fails to
> meet these values it is non-compliant, and does not deserve to be
> called a C compiler.
> 

The "sint16_t" was a typo - it should of course be "int16_t".

For a C99 compiler, "int16_t" is *not* optional unless there are no 
16-bit integer types available on the implementation.  Thus int16_t is 
standard and portable on modern compilers (many non-C99 compilers 
provide "cheap" C99 features, such as // comments and <stdint.h>).

You are perfectly correct in saying that a compiler whose "int" is less 
that 16-bit does not implement the C language correctly (never mind any 
of the standards).  However, the fact remains that in the embedded 
market there are "C" compilers that target 8-bit cpus, have 8-bit ints 
(at least as an option), and are useful and productive tools despite not 
technically being "C".