diff options
Diffstat (limited to 'wirish')
| -rw-r--r-- | wirish/usb_serial.cpp | 67 |
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); } } } |