Flash a LED!

Yesterday, I configured GPIO port C to be able to flash the status LED. I now have two processes yielding to each other. One of them turns on the LED, the other turns it off. Here is one of them. It writes to the GPIO C BSRR (bit set/reset register) to set port C bit 12 high, which turns the LED off.

    .global CM3_proc0
    .thumb_func

CM3_proc0:
    ldr    r1,    =0x40011010 @ PORT C BSRR register.
    mov    r2,    0x00001000  @ Set bit 12.
    str    r2,    [r1]
    mov    r0,    0x1         @ Yield system call.
    svc                       @ Perform the system call.
    mov    r0,    0x800000    @ Delay loop.
loop0:
    sub    r0,    0x1
    cmp    r0,    0x0
    bne    loop0
    b      CM3_proc0