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[usb] Implement jumpReset in assembly.

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This avoids unwanted stack modifications emited by the compiler.

Change-Id: I2a2a13ee5395b95ed676f6634be86eeb148d55fd
This commit is contained in:
Léa Saviot
2018-04-16 10:33:15 +02:00
committed by LeaNumworks
parent f1849cf17e
commit ee6997a07d
2 changed files with 12 additions and 5 deletions
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16
ion/src/device/device.cpp
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@@ -14,7 +14,6 @@ extern "C" {
#include "swd.h"
#include "usb.h"
#include "bench/bench.h"
#include "set_msp.h"
#define USE_SD_CARD 0
@@ -105,9 +104,18 @@ void coreReset() {
void jumpReset() {
uint32_t * stackPointerAddress = reinterpret_cast<uint32_t *>(0x08000000);
uint32_t * resetHandlerAddress = reinterpret_cast<uint32_t *>(0x08000004);
set_msp(*stackPointerAddress);
void (*ResetHandler)(void) = (void (*)())(*resetHandlerAddress);
ResetHandler();
/* Jump to the reset service routine after having reset the stack pointer.
* Both addresses are fetched from the base of the Flash memory, just like a
* real reset would. These operations should be made at once, otherwise the C
* compiler might emit some instructions that modify the stack inbetween. */
asm volatile (
"msr MSP, %[stackPointer] ; bx %[resetHandler]"
: :
[stackPointer] "r" (*stackPointerAddress),
[resetHandler] "r" (*resetHandlerAddress)
);
}
void init() {

1
ion/src/device/usb/Makefile
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@@ -45,7 +45,6 @@ dfu_objs += ion/src/device/usb/boot.o
dfu_objs += ion/src/device/keyboard.o
dfu_objs += ion/src/device/device.o
dfu_objs += ion/src/device/usb.o
dfu_objs += ion/src/device/set_msp.o
ion/src/device/usb/dfu.elf: LDFLAGS = --gc-sections -T ion/src/device/usb/dfu.ld
ion/src/device/usb/dfu.elf: $(usb_objs) $(dfu_objs)