From 68c483e3c9c382779d2580598fb0f90a9f55d2ab Mon Sep 17 00:00:00 2001
From: Perry Hung <iperry@gmail.com>
Date: Sun, 27 Feb 2011 17:26:19 -0500
Subject: Set NONEBASETHRDENA on exception.

---
 libmaple/exc.S  | 40 +++++++++++++++++++++++++---------------
 libmaple/util.c | 50 ++++++++++++++++++++++++++++++++------------------
 libmaple/util.h |  1 +
 3 files changed, 58 insertions(+), 33 deletions(-)

(limited to 'libmaple')

diff --git a/libmaple/exc.S b/libmaple/exc.S
index d01e3d5..823bbc5 100644
--- a/libmaple/exc.S
+++ b/libmaple/exc.S
@@ -48,40 +48,50 @@
 .globl __exc_busfault
 .globl __exc_usagefault
 
-/* TODO: Fix this up. */
+.code 16
 .thumb_func
 __exc_nmi:
     mov r0, #1
+    b __default_exc
 
 .thumb_func
 __exc_hardfault:
     mov r0, #2
+    b __default_exc
 
 .thumb_func
 __exc_memmanage:
     mov r0, #3
+    b __default_exc
 
 .thumb_func
 __exc_busfault:
     mov r0, #4
+    b __default_exc
 
 .thumb_func
 __exc_usagefault:
     mov r0, #5
+    b __default_exc
 
-__default:
-   ldr r1, CPSR_MASK           @ Set default CPSR
-   push {r1}
-   ldr r1, TARGET_PC           @ Set target pc
-   push {r1}
-   sub sp, sp, #24             @ Don't care
-   ldr r1, EXC_RETURN          @ Return to thread mode
-   mov lr, r1
-   bx lr                       @ Exception exit
-
- .align 4
- CPSR_MASK:  .word 0x61000000
- EXC_RETURN: .word 0xFFFFFFF9
- TARGET_PC:  .word throb
+.thumb_func
+__default_exc:
+    ldr r2, NVIC_CCR            @ Enabling returning to thread mode from an
+    mov r1 ,#1                  @ exception. See flag NONEBASETHRDENA.
+    str r1, [r2]
+    cpsid i                     @ Disable global interrupts
+    ldr r1, CPSR_MASK           @ Set default CPSR
+    push {r1}
+    ldr r1, TARGET_PC           @ Set target pc
+    push {r1}
+    sub sp, sp, #24             @ Don't care
+    ldr r1, EXC_RETURN          @ Return to thread mode
+    mov lr, r1
+    bx lr                       @ Exception exit
 
+.align 4
+CPSR_MASK:  .word 0x61000000
+EXC_RETURN: .word 0xFFFFFFF9
+TARGET_PC:  .word __error
+NVIC_CCR:   .word 0xE000ED14    @ NVIC configuration control register
 
diff --git a/libmaple/util.c b/libmaple/util.c
index 481cd60..3408a2e 100644
--- a/libmaple/util.c
+++ b/libmaple/util.c
@@ -49,14 +49,14 @@
 #define HAVE_ERROR_LED
 #endif
 
-/* Error assert + fade */
-void _fail(const char* file, int line, const char* exp) {
-    int32  slope   = 1;
-    uint32 CC      = 0x0000;
-    uint32 TOP_CNT = 0x02FF;
-    uint32 i       = 0;
-
-    /* Turn off interrupts */
+/**
+ * @brief Disables all peripheral interrupts except USB and fades the
+ * error LED.
+ *
+ * Called from exc.S with global interrupts disabled.
+ */
+void __error(void) {
+    /* Turn off peripheral interrupts */
     nvic_irq_disable_all();
 
     /* Turn off timers  */
@@ -68,6 +68,24 @@ void _fail(const char* file, int line, const char* exp) {
     /* Turn off all usarts */
     usart_disable_all();
 
+    /* Turn the USB interrupt back on so the bootloader keeps on functioning */
+    nvic_irq_enable(NVIC_INT_USBHP);
+    nvic_irq_enable(NVIC_INT_USBLP);
+
+    /* Reenable global interrupts */
+    nvic_globalirq_enable();
+    throb();
+}
+
+/**
+ * @brief Prints an error message on a uart upon a failed assertion
+ *      and error throbs.
+ * @param file Source file of failed assertion
+ * @param line Source line of failed assertion
+ * @param exp String representation of failed assertion
+ * @sideeffect Turns of all peripheral interrupts except USB.
+ */
+void _fail(const char* file, int line, const char* exp) {
     /* Initialize the error usart */
     gpio_set_mode(ERROR_TX_PORT, ERROR_TX_PIN, GPIO_MODE_AF_OUTPUT_PP);
     usart_init(ERROR_USART_NUM, ERROR_USART_BAUD);
@@ -82,19 +100,15 @@ void _fail(const char* file, int line, const char* exp) {
     usart_putc(ERROR_USART_NUM, '\n');
     usart_putc(ERROR_USART_NUM, '\r');
 
-#ifdef HAVE_ERROR_LED
-    /* Turn on the error LED */
-    gpio_set_mode(ERROR_LED_PORT, ERROR_LED_PIN, GPIO_MODE_OUTPUT_PP);
-#endif
-
-    /* Turn the USB interrupt back on so the bootloader keeps on functioning */
-    nvic_irq_enable(NVIC_INT_USBHP);
-    nvic_irq_enable(NVIC_INT_USBLP);
-
     /* Error fade */
-    throb();
+    __error();
 }
 
+
+/**
+ * @brief Fades the error LED on and off
+ * @sideeffect Sets output push-pull on ERROR_LED_PIN.
+ */
 void throb(void) {
 #ifdef HAVE_ERROR_LED
     int32  slope   = 1;
diff --git a/libmaple/util.h b/libmaple/util.h
index 28ce970..fb524c2 100644
--- a/libmaple/util.h
+++ b/libmaple/util.h
@@ -79,6 +79,7 @@ extern "C"{
 #define __write(reg, value)      (*(volatile uint32*)(reg) = (value))
 
 #define IS_POWER_OF_TWO(v)  (v && !(v & (v - 1)))
+void __error(void);
 void _fail(const char*, int, const char*);
 void throb(void);
 
-- 
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