First commit

.gitignore

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+bin/
+obj/
+.swp
+

Makefile

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+.POSIX:
+CCX=arm-none-eabi-g++
+CCFLAGS=-c -Wall -fno-stack-protector -ffreestanding -march=armv7-a -nostdlib -Iinclude -g
+
+C_HDR=$(wildcard include/*.h)
+C_SRC=$(wildcard src/*.cpp)
+C_OBJ=$(patsubst src/%.cpp, obj/c_%.o, $(C_SRC))
+
+A_SRC=$(wildcard src/*.s)
+A_OBJ=$(patsubst src/%.s, obj/s_%.o, $(A_SRC))
+
+.PHONY: all environ clean
+
+all: environ bin/kernel.elf
+
+environ:
+	mkdir -p bin
+	mkdir -p obj
+
+bin/kernel.elf: environ $(A_OBJ) $(C_OBJ)
+	arm-none-eabi-ld --nmagic -nostdlib -T src/linker.ld -o bin/kernel.elf obj/*.o
+	# maybe -msomearch
+
+obj/s_%.o: src/%.s
+	$(CCX) $(CCFLAGS) -o $@ $<
+
+obj/c_%.o: src/%.cpp $(C_HDR)
+	$(CCX) $(CCFLAGS) -o $@ $<
+
+clean:
+	rm -f bin/*
+	rm -f obj/*
+

dbg/qemu.sh

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+#!/bin/bash
+
+qemu-system-arm -M virt -cpu cortex-a15 -nographic -kernel bin/kernel.elf -s -S
+

src/kernel.cpp

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+extern "C" int f(int a) {
+	return a + 1;
+}

src/kernel.s

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+.extern f
+
+.text
+my_string:
+    .string "HELLO WORLD!\r\n\r\n"
+    .quad 0x00
+    .quad 0x5a
+
+.align 4
+.global _start
+_start:
+    /* does nothing special */
+	mov r13, #0x8000
+
+    mov r1, #16
+
+1:
+    ldr r0, =my_string
+    bl printk
+    sub r1, #1
+    cmp r1, #0
+    b 1b
+
+lup:
+    b lup
+
+
+.global printk
+printk:
+    stmfd r13!, {r0, r1, r2, r3, r4, r14}
+
+    /* disable UART interrupts */
+    mov r2, #0x8004
+    movt r2, #0x01c2
+
+    ldr r1, [r2]
+    and r1, #0xfffffffc
+    str r1, [r2]
+
+    /* mask interrupts in CPU */
+    cpsid if
+
+    /* TBR */
+    mov r2, #0x8000
+    movt r2, #0x01c2
+
+1:
+    ldr r1, [r0]
+    add r0, #4
+
+    mov r4, #4
+2:
+    and r3, r1, #0xff
+    mov r1, r1, lsr#8
+    cmp r3, #0
+    beq 3f
+    str r3, [r2]
+    sub r4, #1
+    cmp r4, #0
+    bne 2b
+    b 1b
+3:
+
+    ldmfd r13!, {r0, r1, r2, r3, r4, r15}
+

src/linker.ld

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+ENTRY(_start)
+
+SECTIONS
+{
+	. = 0x10000;
+	.text : {
+		*(.text)
+	}
+	.data : ALIGN(0x1000) {
+		*(.data)
+	}
+	.bss : ALIGN(0x1000) {
+		*(.bss)
+	}
+}