initial commit

.gitignore

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+*.o
+*.elf
+*.bin

Makefile

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+debug:
+	openocd -f interface/stlink.cfg -f target/stm32f4x.cfg
+
+all:
+	arm-none-eabi-gcc -x assembler-with-cpp -c -O0 -mcpu=cortex-m0 -mthumb -Wall core.S -o core.o
+	arm-none-eabi-gcc core.o -mcpu=cortex-m0 -mthumb -Wall -nostdlib -lgcc -T./linker.ld -o main.elf
+	arm-none-eabi-objcopy -O binary main.elf main.bin

core.S

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+.syntax unified
+.cpu cortex-m0
+.fpu softvfp
+.thumb
+
+.global vtable
+.global reset_handler
+
+.type vtable, %object
+vtable:
+    .word _estack
+    .word reset_handler
+.size vtable, .-vtable
+
+.type reset_handler, %function
+reset_handler:
+  LDR  r0, =_estack
+  MOV  sp, r0
+
+  LDR  r7, =0xDEADBEEF
+  MOVS r0, #0
+  main_loop:
+    ADDS r0, r0, #1
+    B    main_loop
+.size reset_handler, .-reset_handler

linker.ld

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+_estack = 0x20001000;
+
+MEMORY
+{
+    FLASH ( rx )      : ORIGIN = 0x08000000, LENGTH = 1024K
+    RAM ( rxw )       : ORIGIN = 0x20000000, LENGTH = 256K
+}