MSP430F249: delay with Timers

This is one of those things that everyone seems to need but there are no public examples for. Here's a small/simple one.

It uses Timer A ("TA0" below), but could be changed to use Timer B ("TB0"). I ran this on a G2553 on a Launchpad.

Standard disclaimer: No warranty, no support and all that.

[Edit: Fixed typo]

///
//      tddemo.c
//      Simple delay and clock using Timer A0.
//      Set DEMO=1 to demonstrate.
//      No warranty, no support, and all that.
//
#define DEMO    1                   // Include the main() program below

#include <stdint.h>
#include <msp430.h> 
#define HZ          1000000UL       // Clock is ~1MHz at Reset

//#include "timer.h"                // You'll probably want one of these eventually
extern void timer_init(void);       // You can
extern void timer_wait_ms(uint16_t ms); // put these
extern uint16_t timer_fetch(void);  //        into it

volatile uint16_t timer_ms;
#pragma vector=TIMER0_A0_VECTOR
__interrupt void
timer_isr(void)
{
    ++timer_ms;                     // Clock tick
    LPM0_EXIT;                      // Wake up foreground
    return;
}

void
timer_init(void)
{
    TA0CCR0 = HZ / 1000 - 1;       // 1ms tick
    TA0CCTL0 = CCIE;               // Interrupt up there
    TA0CTL = TASSEL_2 | ID_0 | MC_1 | TACLR; // SMCLK/1, Up mode (,clear)
    return;
}

uint16_t
timer_fetch(void)
{
    return (timer_ms);              // That was easy
}

void
timer_wait_ms(uint16_t ms)
{
    uint16_t start = timer_fetch();
    while (timer_fetch() - start < ms)  // Differencing avoids some races
        LPM0;                           // Wake up every 1ms to look.
    return;
}

#if DEMO
///
//  main()
//
int
main(void)
{
    WDTCTL = WDTPW | WDTHOLD;	// stop watchdog timer
    //  Launchpad P1.0 LED
    P1OUT &= ~BIT0;             // Initially off (active high)
    P1DIR |= BIT0;              // Output
    timer_init();
    __enable_interrupt();

    while (1)
    {
        P1OUT ^= BIT0;          // Toggle LED for show
        timer_wait_ms(500);     // 500ms -> 1Hz blink
    }
    /*NOTREACHED*/
    return 0;
}
#endif  // DEMO