src/pru-back.S

   1 /*
   2  * Copyright (c) 2016, Ian Sutton <ian@kremlin.cc>
   3  *
   4  * Permission to use, copy, modify, and/or distribute this software for
   5  * any purpose with or without fee is hereby granted, provided that the
   6  * above copyright notice and this permission notice appear in all
   7  * copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
  10  * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
  11  * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
  12  * AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  13  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  14  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  15  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  16  * PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 .origin 0
  20 .entrypoint START /* used by debugger only */
  21
  22 #define PERIOD 200000
  23 #define DUTY   100000
  24
  25 START:
  26         SET     r30, r30, 14
  27         MOV     r1, PERIOD
  28         MOV     r2, DUTY
  29         SUB     r3, r1, r2
  30         SUB     r2, r2, 4
  31
  32 ON:
  33         SUB     r2, r2, 1
  34         QBNE    ON, r2, 0
  35         CLR     r30, r30, 14
  36
  37 OFF:
  38         SUB     r3, r3, 1
  39         QBNE    OFF, r3, 0
  40         QBA     START
  41
  42
  43 /*STOP:
  44         MOV     R31.b0, PRU0_R31_VEC_VALID | SIGNUM
  45         HALT*/
  46
  47