Getting precise timings out of RS-232 output

For uninteresting reasons I need very regular 58Hz pulses coming out of an RS-232 Tx line: the time between each pulse should be as close to 1/58s as possible. I produce each pulse by writing an \xFF byte to the device. The start bit is the only active-voltage bit being sent, and that produces my pulse. I wrote this obvious C program: #include <stdio.h> #include <stdlib.h> #include <stdbool.h>…