contrib: replace the GPLv2-or-later license tag

[fw/openocd] / contrib / loaders / flash / nrf5 / nrf5.S

diff --git a/contrib/loaders/flash/nrf5/nrf5.S b/contrib/loaders/flash/nrf5/nrf5.S
index b148e3caf816052f2b58802b23ecaa30c2ba274e..4115b0311e6fc60830107528c8e650d63bab728a 100644 (file)
--- a/contrib/loaders/flash/nrf5/nrf5.S
+++ b/contrib/loaders/flash/nrf5/nrf5.S
@@ -1,24 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
 /***************************************************************************
  *   Copyright (C) 2014 Angus Gratton                                      *
  *   gus@projectgus.com                                                    *
- *                                                                         *
- *   This program is free software; you can redistribute it and/or modify  *
- *   it under the terms of the GNU General Public License as published by  *
- *   the Free Software Foundation; either version 2 of the License, or     *
- *   (at your option) any later version.                                   *
- *                                                                         *
- *   This program is distributed in the hope that it will be useful,       *
- *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
- *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
- *   GNU General Public License for more details.                          *
- *                                                                         *
- *   You should have received a copy of the GNU General Public License     *
- *   along with this program; if not, write to the                         *
- *   Free Software Foundation, Inc.                                        *
  ***************************************************************************/
 
        .text
        .syntax unified
+       .cpu cortex-m0
        .thumb
 
 /*
@@ -27,29 +16,43 @@
  * r1 = buffer start
  * r2 = buffer end
  * r3 = target address
+ * r6 = watchdog refresh value
+ * r7 = watchdog refresh register address
  */
 
        .thumb_func
        .global _start
 _start:
 wait_fifo:
+       // Kick the watchdog
+       str     r6, [r7, #0]
+       // Load write pointer
        ldr     r5, [r1, #0]
+       // Abort if it is NULL
        cmp     r5, #0
        beq.n   exit
+       // Load read pointer
        ldr     r4, [r1, #4]
+       // Continue waiting if it equals the write pointer
        cmp     r4, r5
        beq.n   wait_fifo
+       // Copy one word from buffer to target, and increment pointers
        ldmia   r4!, {r5}
        stmia   r3!, {r5}
+       // If at end of buffer, wrap back to buffer start
        cmp     r4, r2
        bcc.n   no_wrap
        mov     r4, r1
        adds    r4, #8
 no_wrap:
+       // Update read pointer inside the buffer
        str     r4, [r1, #4]
+       // Deduce the word transferred from the byte count
        subs    r0, #4
+       // Start again
        bne.n   wait_fifo
 exit:
+       // Wait for OpenOCD
        bkpt    #0x00
 
        .pool