From 6587c8498ffe2a50bc9c8eb6d490e9d874678bfc Mon Sep 17 00:00:00 2001
From: Matte23 <matteo@underdesk.net>
Date: Sat, 2 Nov 2024 19:07:52 +0100
Subject: [PATCH] Add base code

---
 .gdbinit       |  2 ++
 .gitignore     | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++
 Makefile       | 44 ++++++++++++++++++++++++++++++++++++++++
 libc/library.c | 10 +++++++++
 libc/library.h |  1 +
 linker.ld      | 15 ++++++++++++++
 os/Makefile    | 22 ++++++++++++++++++++
 os/alloc.c     | 14 +++++++++++++
 os/alloc.h     |  4 ++++
 os/main.c      | 17 ++++++++++++++++
 10 files changed, 184 insertions(+)
 create mode 100644 .gdbinit
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 libc/library.c
 create mode 100644 libc/library.h
 create mode 100644 linker.ld
 create mode 100644 os/Makefile
 create mode 100644 os/alloc.c
 create mode 100644 os/alloc.h
 create mode 100644 os/main.c

diff --git a/.gdbinit b/.gdbinit
new file mode 100644
index 0000000..ea0b84e
--- /dev/null
+++ b/.gdbinit
@@ -0,0 +1,2 @@
+target remote :1234
+b main
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..9d6796a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,55 @@
+# Prerequisites
+*.d
+
+# Object files
+*.o
+*.ko
+*.obj
+*.elf
+
+# Linker output
+*.ilk
+*.map
+*.exp
+
+# Precompiled Headers
+*.gch
+*.pch
+
+# Libraries
+*.lib
+*.a
+*.la
+*.lo
+
+# Shared objects (inc. Windows DLLs)
+*.dll
+*.so
+*.so.*
+*.dylib
+
+# Executables
+*.exe
+*.out
+*.app
+*.i*86
+*.x86_64
+*.hex
+
+# Debug files
+*.dSYM/
+*.su
+*.idb
+*.pdb
+
+# Kernel Module Compile Results
+*.mod*
+*.cmd
+.tmp_versions/
+modules.order
+Module.symvers
+Mkfile.old
+dkms.conf
+
+# GDB
+.gdb_history
\ No newline at end of file
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..36b9686
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,44 @@
+CC = arm-none-eabi-gcc
+AS = arm-none-eabi-as
+LD = arm-none-eabi-ld
+CPU = -mcpu=cortex-m4
+THUMB = -mthumb
+
+LDFLAGS = -T linker.ld
+CFLAGS = $(CPU) $(THUMB)
+
+QEMU = qemu-system-arm
+BOARD = netduino2
+
+# Output file
+TARGET = main.elf
+# Source files
+SRCS = os/main.c os/process.c os/scheduler.c os/alloc.c tasks/library.c tasks/tasks.c
+# Object files
+OBJS = $(SRCS:.c=.o)
+
+debug: CFLAGS += -g
+debug: all
+
+run: debug
+	$(QEMU) -M $(BOARD) -nographic -kernel $(TARGET)
+
+gdb: debug
+	$(QEMU) -M $(BOARD) -nographic -kernel $(TARGET) -s -S
+
+# Default target to build the ELF file
+all: $(TARGET)
+
+$(TARGET): $(OBJS) startup.o
+	$(LD) $(LDFLAGS) startup.o $(OBJS) -o $(TARGET)
+
+startup.o: startup.s
+	$(AS) $(CPU) -g startup.s -o startup.o
+
+# Rule to compile source files into object files
+%.o: %.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+clean:
+	rm -f *.elf *.o *.i
+	rm -f os/*.o tasks/*.o
diff --git a/libc/library.c b/libc/library.c
new file mode 100644
index 0000000..c37f1ee
--- /dev/null
+++ b/libc/library.c
@@ -0,0 +1,10 @@
+#include "library.h"
+
+volatile unsigned int *const USART1_PTR = (unsigned int *)0x40011004;
+
+void puts(const char *s) {
+    while(*s != '\0') { /* Loop until end of string */
+        *USART1_PTR= (unsigned int)(*s); /* Transmit char */
+        s++; /* Next char */
+    }
+}
diff --git a/libc/library.h b/libc/library.h
new file mode 100644
index 0000000..3aa8f9b
--- /dev/null
+++ b/libc/library.h
@@ -0,0 +1 @@
+void puts(const char *s);
diff --git a/linker.ld b/linker.ld
new file mode 100644
index 0000000..8b92698
--- /dev/null
+++ b/linker.ld
@@ -0,0 +1,15 @@
+ENTRY(_start)
+
+SECTIONS
+{
+    /* text section (code)*/
+    .text : { *(.text*) }
+    /* data section, initialized variables */
+    .data : { *(.data) }
+    ram_start = 0x20000000;
+    /* bss section, uninitialized variables */
+    .bss : { *(.bss*) }
+    /* stack section */
+    /* The stack is placed at the end of the RAM */
+    stack_top = 0x2001ffff;
+}
diff --git a/os/Makefile b/os/Makefile
new file mode 100644
index 0000000..642f902
--- /dev/null
+++ b/os/Makefile
@@ -0,0 +1,22 @@
+CC = arm-none-eabi-gcc
+AS = arm-none-eabi-as
+LD = arm-none-eabi-ld
+CPU = -mcpu=cortex-m4
+THUMB = -mthumb
+
+LDFLAGS = -T linker.ld
+CFLAGS = -c $(CPU) $(THUMB) -g
+
+all: main.o process.o scheduler.o
+
+main.o: main.c
+	$(CC) $(CFLAGS) main.c -o main.o
+
+scheduler.o: scheduler.c
+	$(CC) $(CFLAGS) scheduler.c -o scheduler.o
+
+process.o: process.c
+	$(CC) $(CFLAGS) process.c -o process.o
+
+clean:
+	rm -f *.elf *.o *.i
diff --git a/os/alloc.c b/os/alloc.c
new file mode 100644
index 0000000..c2af1b5
--- /dev/null
+++ b/os/alloc.c
@@ -0,0 +1,14 @@
+#include "alloc.h"
+#include "stdint.h"
+
+void* *first_mem_avail = (void*) 0x20000000;
+
+void init_allocator() {
+    *first_mem_avail = (void*) 0x20000000 +sizeof(void*);
+}
+
+void* malloc(size_t size) {
+    void* block = *first_mem_avail;
+    *first_mem_avail += size;
+    return block;
+}
diff --git a/os/alloc.h b/os/alloc.h
new file mode 100644
index 0000000..bfe4861
--- /dev/null
+++ b/os/alloc.h
@@ -0,0 +1,4 @@
+#include <stddef.h>
+
+void init_allocator();
+void* malloc (size_t size);
diff --git a/os/main.c b/os/main.c
new file mode 100644
index 0000000..7d19c5e
--- /dev/null
+++ b/os/main.c
@@ -0,0 +1,17 @@
+#include "process.h"
+#include "scheduler.h"
+#include "alloc.h"
+
+extern int task1(void);
+extern int task2(void);
+
+int main(void) {
+    init_allocator();
+    ProcessTable *ptable;
+    create_process_table(&ptable);
+
+    create_process(ptable, task1);
+    create_process(ptable, task2);
+
+    run(ptable);
+}