@wummi said:
Hi Chip,
I found a strange behavior with REPEAT <count> WITH <variable> when count is zero.
PUB go () | i
repeat 0 with i
debug(sdec(i))
{ debug output
Cog0 i = 0
Cog0 i = -1
}
I expected debug(sdec(i)) is never executed, but it executes twice.
I believe this behavior is expected. The Spin document indicates that the count value is normally expected to be a number greater than 0.
The WITH form of the REPEAT statement is a smaller/faster version than the REPEAT FROM statement.
v40 2023-09-21 ● New smaller/faster REPEAT form added for iterating a variable from 0 to n-1, where n > 0.
REPEAT n WITH i 'best way to iterate a variable from 0 to n - 1
REPEAT i from 0 to n - 1 'general equivalent, though WITH needs n > 0
Example:
_clkfreq = 200_000_000
PUB go () | i,n
repeat 0 with i
debug("with loop: ",sdec(i))
n := 0
repeat i from 0 to n-1
debug("from loop: ",sdec(i))
Output:
Cog0 with loop: i = 0
Cog0 with loop: i = -1
Cog0 from loop: i = 0
Cog0 from loop: i = -1
A new PNut_v51 has been posted at the top of this thread.
v51 - 2025.04.02 - New POW, LOG2, EXP2, LOG10, EXP10, LOG, and EXP floating-point operators. SIZEOF() can now be used by PASM code to get sizes of structures. Long variables within structures can now be used as method pointers. Ignore-multiple-return-values '_ (number_of_longs)' had a stack bug rendering it useless, so it has been fixed and the syntax has been changed to use brackets, instead: '_ [number_of_longs]'.
Comments
I believe this behavior is expected. The Spin document indicates that the count value is normally expected to be a number greater than 0.
The WITH form of the REPEAT statement is a smaller/faster version than the REPEAT FROM statement.
Example: _clkfreq = 200_000_000 PUB go () | i,n repeat 0 with i debug("with loop: ",sdec(i)) n := 0 repeat i from 0 to n-1 debug("from loop: ",sdec(i)) Output: Cog0 with loop: i = 0 Cog0 with loop: i = -1 Cog0 from loop: i = 0 Cog0 from loop: i = -1OK, i do not now that n must be greater than 0
Undefined is not the same as expected.
A new PNut_v51 has been posted at the top of this thread.
v51 - 2025.04.02 - New POW, LOG2, EXP2, LOG10, EXP10, LOG, and EXP floating-point operators. SIZEOF() can now be used by PASM code to get sizes of structures. Long variables within structures can now be used as method pointers. Ignore-multiple-return-values '_ (number_of_longs)' had a stack bug rendering it useless, so it has been fixed and the syntax has been changed to use brackets, instead: '_ [number_of_longs]'.