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-rw-r--r--Makefile2
-rw-r--r--clock.c13
-rw-r--r--heap.c38
-rw-r--r--include/heap.h11
-rw-r--r--include/task.h10
-rw-r--r--link.ld12
-rw-r--r--main.c36
-rw-r--r--startup_stm32l476xx.s2
-rw-r--r--stm32l4xx_it.c14
-rw-r--r--task.c108
10 files changed, 224 insertions, 22 deletions
diff --git a/Makefile b/Makefile
index 4a7a22c..48175ff 100644
--- a/Makefile
+++ b/Makefile
@@ -6,6 +6,8 @@ all:
arm-none-eabi-gcc $(CFLAGS) system_stm32l4xx.c -c -o out/system_stm32l4xx.o
arm-none-eabi-gcc $(CFLAGS) stm32l4xx_it.c -c -o out/stm32l4xx_it.o
arm-none-eabi-gcc $(CFLAGS) clock.c -c -o out/clock.o
+ arm-none-eabi-gcc $(CFLAGS) heap.c -c -o out/heap.o
+ arm-none-eabi-gcc $(CFLAGS) task.c -c -o out/task.o
arm-none-eabi-gcc $(CFLAGS) main.c -c -o out/main.o
arm-none-eabi-gcc $(CFLAGS) -T link.ld out/*.o -o out/main.elf
arm-none-eabi-objcopy -O ihex out/main.elf main.hex
diff --git a/clock.c b/clock.c
index 8041cb2..ab92386 100644
--- a/clock.c
+++ b/clock.c
@@ -45,15 +45,18 @@ void delay(uint32_t count)
while (ticks < target);
}
-void PendSV_Handler(void) {
-}
-
+__attribute__ ((naked))
void SysTick_Handler(void)
{
+ uint32_t lr;
+ asm("mov %0, lr" : "=r" (lr));
+
// just keep counting
ticks++;
- if (!(ticks % 500))
- SCB->ICSR |= SCB_ICSR_PENDSVSET_Msk;
+ if (!(ticks % 10))
+ SCB->ICSR |= SCB_ICSR_PENDSVSET_Msk;
+
+ asm("mov lr, %0; bx lr" :: "r" (lr));
}
diff --git a/heap.c b/heap.c
new file mode 100644
index 0000000..0433a1f
--- /dev/null
+++ b/heap.c
@@ -0,0 +1,38 @@
+#include <heap.h>
+#include <stm32l476xx.h>
+
+#define RAM_END 0x20018000
+
+//extern void *end;
+//extern uint32_t _total_ram;
+static uint32_t offset = 0;
+
+__attribute__ ((section(".data")))
+uint8_t heap[8192];
+void *end = heap;
+
+void heap_init(void)
+{
+ // what to do...
+}
+
+uint32_t heap_available(void)
+{
+ return 0;// return _total_ram - offset;
+}
+
+void *hmalloc(uint32_t size)
+{
+ void *alloc = end + offset;
+ offset += size;
+ return alloc;
+}
+
+void *hcalloc(uint32_t count, uint32_t size)
+{
+ uint32_t total = count * size;
+ void *alloc = hmalloc(total);
+ for (uint32_t i = 0; i < total; i++)
+ ((uint8_t *)alloc)[i] = 0;
+ return alloc;
+}
diff --git a/include/heap.h b/include/heap.h
new file mode 100644
index 0000000..e04b15e
--- /dev/null
+++ b/include/heap.h
@@ -0,0 +1,11 @@
+#ifndef HEAP_H_
+#define HEAP_H_
+
+#include <stdint.h>
+
+uint32_t heap_available(void);
+
+void *hmalloc(uint32_t size);
+void *hcalloc(uint32_t count, uint32_t size);
+
+#endif // HEAP_H_
diff --git a/include/task.h b/include/task.h
new file mode 100644
index 0000000..c57b2c0
--- /dev/null
+++ b/include/task.h
@@ -0,0 +1,10 @@
+#ifndef TASK_H_
+#define TASK_H_
+
+#include <stdint.h>
+
+void task_init(void (*init)(void));
+
+void task_start(void (*task)(void), uint16_t stackSize);
+
+#endif // TASK_H_
diff --git a/link.ld b/link.ld
index e24ff34..8877898 100644
--- a/link.ld
+++ b/link.ld
@@ -34,15 +34,15 @@ ENTRY(Reset_Handler)
/* Highest address of the user mode stack */
_estack = 0x20018000; /* end of RAM */
-/* Generate a link error if heap and stack don't fit into RAM */
-_Min_Heap_Size = 0x200;; /* required amount of heap */
-_Min_Stack_Size = 0x400;; /* required amount of stack */
+
+_Min_Stack_Size = 0x0400; /* 1k min. stack */
+_Min_Heap_Size = 0x0400; /* 1k min. heap */
/* Specify the memory areas */
MEMORY
{
-FLASH (rx) : ORIGIN = 0x8000000, LENGTH = 1024K
-RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 96K
+ FLASH (rx) : ORIGIN = 0x8000000, LENGTH = 1024K
+ RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 96K
}
/* Define output sections */
@@ -166,4 +166,4 @@ SECTIONS
.ARM.attributes 0 : { *(.ARM.attributes) }
}
-
+_total_ram = _estack - _end;
diff --git a/main.c b/main.c
index e640a6b..9a95465 100644
--- a/main.c
+++ b/main.c
@@ -1,21 +1,26 @@
#include <stm32l476xx.h>
#include <clock.h>
+#include <heap.h>
+#include <task.h>
/**
* Accomplishments:
* - GPIO in/out
* - got to 80MHz clock
+ * - basic heap
+ * - multitask, can exit
*/
void pulse(uint8_t byte);
+void kmain(void);
int main(void)
{
+ asm("cpsid i");
+
// prepare flash latency for 40MHz operation
FLASH->ACR &= ~(FLASH_ACR_LATENCY);
- FLASH->ACR |= FLASH_ACR_LATENCY_2WS;
-
- clock_init();
+ FLASH->ACR |= FLASH_ACR_LATENCY_4WS;
RCC->AHB2ENR |= RCC_AHB2ENR_GPIOAEN; // A clk enable
GPIOA->MODER &= ~(GPIO_MODER_MODE5 | GPIO_MODER_MODE6); // A5 -> output, A0 input
@@ -24,16 +29,37 @@ int main(void)
GPIOA->PUPDR |= GPIO_PUPDR_PUPD5_0 | GPIO_PUPDR_PUPD6_0; // pulldown for button (1)
//if (GPIOA->IDR & 0x01)
+ clock_init();
+ task_init(kmain);
+
+ while (1);
+}
+
+void task(void);
+void kmain(void)
+{
+ asm("cpsie i");
+
+ task_start(task, 1024);
while (1) {
+ GPIOA->BSRR |= 1 << 6;
delay(500);
- GPIOA->BSRR |= 1 << 5;
GPIOA->BRR |= 1 << 6;
delay(500);
- GPIOA->BSRR |= 1 << 6;
+ }
+}
+
+void task(void)
+{
+ while (1) {
+ GPIOA->BSRR |= 1 << 5;
+ delay(200);
GPIOA->BRR |= 1 << 5;
+ delay(200);
}
}
+
void _exit(int code)
{ for (;;); }
diff --git a/startup_stm32l476xx.s b/startup_stm32l476xx.s
index b93d40a..57b11cb 100644
--- a/startup_stm32l476xx.s
+++ b/startup_stm32l476xx.s
@@ -62,7 +62,7 @@ defined in linker script */
/* end address for the .bss section. defined in linker script */
.word _ebss
-.equ BootRAM, 0xF1E0F85F
+//.equ BootRAM, 0xF1E0F85F
/**
* @brief This is the code that gets called when the processor first
* starts execution following a reset event. Only the absolutely
diff --git a/stm32l4xx_it.c b/stm32l4xx_it.c
index c3bd859..dc6dc16 100644
--- a/stm32l4xx_it.c
+++ b/stm32l4xx_it.c
@@ -1,25 +1,29 @@
-#include <stdint.h>
+#include <stm32l476xx.h>
void NMI_Handler(void) {}
void HardFault_Handler(void)
{
- while (1);
+ GPIOA->BSRR |= (1 << 5) | (1 << 6);
+ while (1);
}
void MemManage_Handler(void)
{
- while (1);
+ GPIOA->BSRR |= (1 << 5) | (1 << 6);
+ while (1);
}
void BusFault_Handler(void)
{
- while (1);
+ GPIOA->BSRR |= (1 << 5) | (1 << 6);
+ while (1);
}
void UsageFault_Handler(void)
{
- while (1);
+ GPIOA->BSRR |= (1 << 5) | (1 << 6);
+ while (1);
}
void SVC_Handler(void) {}
diff --git a/task.c b/task.c
new file mode 100644
index 0000000..b77d4f5
--- /dev/null
+++ b/task.c
@@ -0,0 +1,108 @@
+#include <task.h>
+#include <heap.h>
+#include <stm32l476xx.h>
+
+typedef struct {
+ uint32_t *sp;
+ uint8_t use;
+ uint32_t *stack;
+ void (*code)(void);
+} task_t;
+
+#define MAX_TASKS 4
+
+static task_t tasks[MAX_TASKS];
+static int next_idx = 0;
+
+void task_init(void (*init)(void))
+{
+ for (int i = 0; i < MAX_TASKS; i++)
+ tasks[i].use = 0;
+
+ task_start(init, 1024);
+ asm("\
+ msr psp, %0; \
+ mrs r0, control; \
+ orr r0, r0, #2; \
+ msr control, r0; \
+ isb; \
+ " :: "r" (tasks[0].sp));
+
+ init();
+
+ // force switch to tasking, call pendsv
+ //SCB->ICSR |= SCB_ICSR_PENDSVSET_Msk;
+}
+
+extern void _exit(int);
+void task_exit(void)
+{
+ // TODO free stack?
+ asm("cpsid i"); // hope to catch next_idx
+ tasks[next_idx].use = 0;
+ asm("cpsie i");
+ while (1); // bye
+ //_exit(0);
+}
+
+void task_start(void (*task)(void), uint16_t stackSize)
+{
+ asm("cpsid i"); // just to be safe
+
+ for (int i = 0; i < MAX_TASKS; i++) {
+ if (tasks[i].use == 0) {
+ tasks[i].stack = hmalloc(stackSize);
+ tasks[i].sp = tasks[i].stack + stackSize - 16;
+ tasks[i].sp[13] = (uint32_t)task_exit;
+ tasks[i].sp[14] = (uint32_t)task;
+ tasks[i].sp[15] = 0x01000000;
+ tasks[i].use = 1;
+ tasks[i].code = task;
+ asm("cpsie i");
+ return;
+ }
+ }
+
+ // TODO handle error
+}
+
+__attribute__ ((naked))
+void PendSV_Handler(void)
+{
+ // save state
+ //stmdb r0!, {r4-r11};
+ asm("\
+ cpsid i; \
+ isb; \
+ dsb; \
+ mrs r0, psp; \
+ stmdb r0!, {r4-r11}; \
+ mov %0, r0; \
+ " : "=r" (tasks[next_idx].sp));
+
+ // find next task (round-robin style)
+ do {
+ if (++next_idx == MAX_TASKS) {
+ next_idx = 0;
+ break; // task 0 better exist
+ }
+ } while (tasks[next_idx].use == 0);
+
+ // restore
+ //ldmia r0!, {r4-r11};
+ asm("\
+ mov r0, %0; \
+ ldmia r0!, {r4-r11}; \
+ msr psp, r0; \
+ isb; \
+ dsb; \
+ " :: "r" (tasks[next_idx].sp));
+
+ // end
+ asm("\
+ mov r0, #0xFFFFFFFD; \
+ cpsie i; \
+ bx r0; \
+ ");
+}
+
generated by cgit v1.2.3 (git 2.39.1) at 2025-06-28 05:57:55 +0000