Add set_ratio in systick

Author: cla7aye15I4nd

examples/mcu/stm32f4_hack_lock.py

@@ -27,7 +27,11 @@ def crack(passwd):
     ql = Qiling(["../../examples/rootfs/mcu/stm32f407/backdoorlock.hex"],                    
                         archtype="cortex_m", profile="stm32f407", verbose=QL_VERBOSE.OFF)
 
+    ql.hw.create('spi2')
+    ql.hw.create('gpioe')
+    ql.hw.create('gpiof')
     ql.hw.create('usart1')
+    ql.hw.create('rcc')
 
     ql.hw.show_info()
 
@@ -40,7 +44,8 @@ def crack(passwd):
 
     ql.hw.usart1.send(passwd.encode() + b'\r')
 
-    ql.run(count=300000, end=0x8003225)
+    ql.hw.systick.set_ratio(100)
+    ql.run(count=1000000, end=0x8003225)
     if ql.arch.get_pc() == 0x8003225:
         print('Success, the passwd is', passwd)
     else:

qiling/hw/timer/cm4_systick.py

@@ -26,7 +26,10 @@ def __init__(self, ql, label):
         )        
 
         # Maybe we will want to customize the timer speed in the future
-        self.RATIO = 1        
+        self.ratio = 1
+
+    def set_ratio(self, ratio):
+        self.ratio = ratio
 
     def step(self):
         if not self.systick.CTRL & SYSTICK_CTRL.ENABLE:
@@ -39,7 +42,7 @@ def step(self):
             if self.systick.CTRL & SYSTICK_CTRL.TICKINT:
                 self.ql.hw.nvic.set_pending(IRQ.SYSTICK)
         else:
-            self.systick.VAL -= self.RATIO
+            self.systick.VAL -= self.ratio
 
     def read(self, offset: int, size: int) -> int:       
         self.ql.log.debug(f'[{self.label.upper()}] [R] {self.find_field(offset, size):10s}')