implementation of interrupts, SysTick exception

[cortex-from-scratch] / ivt.c

diff --git a/ivt.c b/ivt.c
index fadf533..ba617ef 100644 (file)
--- a/ivt.c
+++ b/ivt.c
@@ -4,82 +4,49 @@
 #include <stm32.h>
 #include <mmap.h>
 
-/* TIMER, TODO: move to timer.c */
-
-
+/* 
+ * Vector table, each entry contains an interrupt
+ * service routine:  * 
+ *
+ * interrupt vector 1-15: processor exceptions
+ * interrupt vector 16-32: irq0 - irq ..
+ * */
 
-/* Interrupt vector can contain 16 exceptions and up to 256 interrupts
- * In this code we use 16 exceptions and 36 interrupts  
- * (note: this should be aligned to the vector table size) 
- * Offsets of each entry is:  0x0, 0x80, 0x100, 0x180 .. */
+uint32_t ivt[32];
 
-/* interrupt vector 1-15: processor exceptions
- * interrupt vector 16-43: irq0 - irq .. */
-uint32_t ivt[43];
 
-/* * base is location of interrupt service request
- * */
 void ivt_set_gate(unsigned char num, void * isr(), short pri) {
 
        ivt[num] = (uint32_t) isr;
-       // TODO priority
+       *NVIC_ISER0 = (1 << ((uint32_t)(num) & 0x1F));
+       /* Priorities */
 }
 
-// test Interrupt service routine
-void * test_ISR() {
-       uart_puts("PING!");
+
+/* Dummy interrupt */
+void * dummy_isr() {
+
 }
 
 /* Initialize interrupt vector  */
-
 void ivt_init() {
 
        /* clear entiry IVT, in SRAM location for SRAM + .data (in .bss section) */
-       memset(&ivt, 0, (sizeof(uint32_t) * 44));
+       memset(&ivt, 0, (sizeof(uint32_t) * 87));
 
        // stack top is loaded from the first entry table on boot/reset
        // don't need to relocate or init this here
-
-       // copy old vectors 
        extern void * reset,  * nmi, * hardfault;
-       //extern uint32_t reset, nmi, hardfault;
-       //ivt[1] = &reset;
-       //ivt[2] = &nmi;
-       //ivt[3] = &hardfault;
-
-       ivt_set_gate(1, test_ISR, 0);
-       ivt_set_gate(2, test_ISR, 0);
-       ivt_set_gate(3, test_ISR, 0);
-       ivt_set_gate(15, test_ISR ,0);
-
-       // enable all interrupts
-       
-       *SYSCTRL_RCGC1 = *SYSCTRL_RCGC1 | 0x00010000;
-
-       // TODO systimer 
-       // ivt[15]
-       *NVIC_EN0 = *NVIC_EN0 | 0x00008003;
-//     *NVIC_EN1 = (volatile uint32_t) 0xFFFFFFFF; // TODO not all registers
-
-       // priority levels are 0 by default (only executable by kernel)
-       
-       /* disable all interrupts
-        * MOV R0, #1 ; disable all
-        * MSR PRIMASK, R0 
-        * MOV R0, #0 ; allow all
-        * MSR PRIMASK, R0 */
 
-       
-       
-       /* relocate the vector table to (S)RAM 
-        * vector table starts at 0x0. since the address 0x0 point to bootcode, it is on ROM or FLASH. 
-        * the value cannot be changed during runtime. however, the vector table can be
-        * relocated to other memory locations in the code or RAM later on
-        *
-        * we can do this by setting a register in the NVIC called
-        * the vector table offset register (address 0xE000ED08).  */
+       ivt_set_gate(1, dummy_isr, 0);
+       ivt_set_gate(2, dummy_isr, 0);
+       ivt_set_gate(3, dummy_isr, 0);
 
+       /* the vector table starts at 0x0. Since the address 0x0 point to 
+        * bootcode, it is on ROM or FLASH. The vector table can be
+        * relocated to other memory locations. We can do this by setting 
+        * a register in the NVIC called the vector table offset register */
 
-       *NVIC_VECTTBL = (volatile unsigned long) &ivt; 
+       *SCB_VTOR = (volatile uint32_t) &ivt; 
 
 }