apple2_prodos_utils/itoa.comma.h
2017-11-05 22:06:50 -08:00

50 lines
1.6 KiB
C

/**
@param {uint64_t} x - Number to convert to comma delimited string
@param {char*} [output_] - Optional buffer to copy output to
@return {char*} Returns pointer to comma delimited NULL terminated string
@notes Does NOT NULL terminate the output_ string (to allow for string concatenation)
@history
version 9 - Renamed p,e to dst, end
Version 8 - Cleanup notes
Version 7 - cleanup 'x > 9' to 'x > 0'
Version 6 - Add jsdoc
Verison 5 - add optional output, does NOT null terminate output
Version 4 - document hard-coded max string length 32
Version 3 - cleanup '>= 10' to '> 9'
Verison 2 - add 4 buffers
Version 1 - initial implementation
*/
const char*
itoa_comma( uint64_t x, char *output_ = NULL )
{
const int MAX_CHARS = 31; // 2^32 - 1 = 4,294,967,295 = 13 chars
const int NUM_BUFFERS = 4; // 2^64 - 1 = 18,446,744,073,709,551,615 = 26 chars
static char aString[ NUM_BUFFERS ][ MAX_CHARS+1 ];
static uint8_t iString = 0;
char *dst = &aString[ iString ][ MAX_CHARS ];
char *end = dst; // save copy of end pointer
*dst-- = 0;
while( x > 999 )
{
*dst-- = '0' + (x % 10); x /= 10;
*dst-- = '0' + (x % 10); x /= 10;
*dst-- = '0' + (x % 10); x /= 10;
*dst-- = ',';
}
/* */ { *dst-- = '0' + (x % 10); x /= 10; }
if (x > 0) { *dst-- = '0' + (x % 10); x /= 10; }
if (x > 0) { *dst-- = '0' + (x % 10); x /= 10; }
iString++;
iString &= (NUM_BUFFERS-1);
if( output_ )
memcpy( output_, dst+1, end-dst-1 ); // -1 to NOT include NULL terminator
return ++dst;
}