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-rw-r--r--wirish/usb_serial.cpp67
1 files changed, 33 insertions, 34 deletions
diff --git a/wirish/usb_serial.cpp b/wirish/usb_serial.cpp
index bf2ea4e..af0d710 100644
--- a/wirish/usb_serial.cpp
+++ b/wirish/usb_serial.cpp
@@ -31,6 +31,7 @@
#include <wirish/usb_serial.h>
#include <string.h>
+#include <stdint.h>
#include <libmaple/nvic.h>
#include <libmaple/usb_cdcacm.h>
@@ -199,46 +200,44 @@ static void rxHook(unsigned hook, void *ignored) {
if (usb_cdcacm_data_available() >= 4) {
// The magic reset sequence is "1EAF".
- uint8 cmpBuf[4] = {'1', 'E', 'A', 'F'};
+ static const uint8 magic[4] = {'1', 'E', 'A', 'F'};
uint8 chkBuf[4];
- // Peek at the waiting bytes, looking for reset sequence.
+ // Peek at the waiting bytes, looking for reset sequence,
+ // bailing on mismatch.
usb_cdcacm_peek(chkBuf, 4);
- bool cmpMatch = true;
- for (int i = 0; i < 4; i++) {
- if (chkBuf[i] != cmpBuf[i]) {
- cmpMatch = false;
- break;
+ for (unsigned i = 0; i < sizeof(magic); i++) {
+ if (chkBuf[i] != magic[i]) {
+ return;
}
}
- // Got the magic sequence? Reset, presumably into the bootloader.
- if (cmpMatch) {
- // Return address is wait_reset, but we must set the thumb bit.
- unsigned int target = (unsigned int)wait_reset | 0x1;
- asm volatile("mov r0, %[stack_top] \n\t" // Reset stack
- "mov sp, r0 \n\t"
- "mov r0, #1 \n\t"
- "mov r1, %[target_addr] \n\t"
- "mov r2, %[cpsr] \n\t"
- "push {r2} \n\t" // Fake xPSR
- "push {r1} \n\t" // PC target addr
- "push {r0} \n\t" // Fake LR
- "push {r0} \n\t" // Fake R12
- "push {r0} \n\t" // Fake R3
- "push {r0} \n\t" // Fake R2
- "push {r0} \n\t" // Fake R1
- "push {r0} \n\t" // Fake R0
- "mov lr, %[exc_return] \n\t"
- "bx lr"
- :
- : [stack_top] "r" (STACK_TOP),
- [target_addr] "r" (target),
- [exc_return] "r" (EXC_RETURN),
- [cpsr] "r" (DEFAULT_CPSR)
- : "r0", "r1", "r2");
- /* should never get here */
- }
+ // Got the magic sequence -> reset, presumably into the bootloader.
+ // Return address is wait_reset, but we must set the thumb bit.
+ uintptr_t target = (uintptr_t)wait_reset | 0x1;
+ asm volatile("mov r0, %[stack_top] \n\t" // Reset stack
+ "mov sp, r0 \n\t"
+ "mov r0, #1 \n\t"
+ "mov r1, %[target_addr] \n\t"
+ "mov r2, %[cpsr] \n\t"
+ "push {r2} \n\t" // Fake xPSR
+ "push {r1} \n\t" // PC target addr
+ "push {r0} \n\t" // Fake LR
+ "push {r0} \n\t" // Fake R12
+ "push {r0} \n\t" // Fake R3
+ "push {r0} \n\t" // Fake R2
+ "push {r0} \n\t" // Fake R1
+ "push {r0} \n\t" // Fake R0
+ "mov lr, %[exc_return] \n\t"
+ "bx lr"
+ :
+ : [stack_top] "r" (STACK_TOP),
+ [target_addr] "r" (target),
+ [exc_return] "r" (EXC_RETURN),
+ [cpsr] "r" (DEFAULT_CPSR)
+ : "r0", "r1", "r2");
+ /* Can't happen. */
+ ASSERT_FAULT(0);
}
}
}