Merge remote branch 'upstream/master'

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diff --git a/libmaple/exc.S b/libmaple/exc.S
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+/* *****************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 Perry Hung.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ * ****************************************************************************/
+
+# On an exception, push a fake stack thread mode stack frame and redirect
+# thread execution to a thread mode error handler
+
+# From RM008:
+# The SP is decremented by eight words by the completion of the stack push.
+# Figure 5-1 shows the contents of the stack after an exception pre-empts the
+# current program flow.
+#
+# Old SP--> <previous>
+#           xPSR
+#           PC
+#           LR
+#           r12
+#           r3
+#           r2
+#           r1
+#    SP-->  r0
+
+.text
+.globl HardFaultException
+.thumb_func
+HardFaultException:
+   ldr r0, CPSR_MASK           @ Set default CPSR
+   push {r0}
+   ldr r0, TARGET_PC           @ Set target pc
+   push {r0}
+   sub sp, sp, #24             @ its not like i even care
+   ldr r0, EXC_RETURN          @ Return to thread mode
+   mov lr, r0
+   bx lr                       @ Exception exit
+
+ .align 4
+ CPSR_MASK:  .word 0x61000000
+ EXC_RETURN: .word 0xFFFFFFF9
+ TARGET_PC:  .word throb
+
+