From 6df3f203b8884b2bf5410062f4c51cfdffe7aea9 Mon Sep 17 00:00:00 2001
From: ngiddings <nathang567@gmail.com>
Date: Mon, 19 Apr 2021 06:51:48 -0500
Subject: [PATCH] Added source file for syscalls

---
 include/syscalls.h |  9 +++++
 src/Makefile.am    |  2 +-
 src/syscalls.c     | 83 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 include/syscalls.h
 create mode 100644 src/syscalls.c

diff --git a/include/syscalls.h b/include/syscalls.h
new file mode 100644
index 0000000..e2aafa3
--- /dev/null
+++ b/include/syscalls.h
@@ -0,0 +1,9 @@
+#pragma once
+
+#include "kernel.h"
+
+size_t test_syscall(struct kernel_t *kernel, size_t arg1, size_t arg2, size_t arg3);
+
+size_t mmap(struct kernel_t *kernel, size_t location, size_t length, size_t flags);
+
+size_t munmap(struct kernel_t *kernel, size_t location, size_t length, size_t arg3);
diff --git a/src/Makefile.am b/src/Makefile.am
index 8f5c591..90ff4d9 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,5 +1,5 @@
 noinst_PROGRAMS = quark-kernel
-quark_kernel_SOURCES = kernel.c memorymap.c pageallocator.c priorityqueue.c stdio.c string.c elf.c resource.c allocator.c
+quark_kernel_SOURCES = kernel.c memorymap.c pageallocator.c priorityqueue.c stdio.c string.c elf.c resource.c allocator.c syscalls.c
 quark_kernel_LDADD = -lgcc
 quark_kernel_CFLAGS = -I$(top_srcdir)/include -ffreestanding -mgeneral-regs-only -O0 -Wall -ggdb
 quark_kernel_LDFLAGS = -nostdlib
diff --git a/src/syscalls.c b/src/syscalls.c
new file mode 100644
index 0000000..687e4f2
--- /dev/null
+++ b/src/syscalls.c
@@ -0,0 +1,83 @@
+#include "syscalls.h"
+#include "kernel.h"
+#include "mmgr.h"
+#include "stdio.h"
+#include "types/status.h"
+
+size_t test_syscall(struct kernel_t *kernel, size_t arg1, size_t arg2, size_t arg3)
+{
+    printf("%s", (char*)arg1);
+    return 17;
+}
+
+size_t mmap(struct kernel_t *kernel, size_t location, size_t length, size_t flags)
+{
+    if(location % page_size != 0 || length % page_size != 0)
+    {
+        return S_INVALID_ARGUMENT;
+    }
+    else if(location == NULL)
+    {
+        return S_NULL_POINTER;
+    }
+    for(size_t i = 0; i < length; i += page_size)
+    {
+        if(page_type((void*)(location + i)) != PAGE_NOT_PRESENT)
+        {
+            return S_EXISTS;
+        }
+    }
+    size_t n = 0;
+    int status = S_OK;
+    while(n < length && status == S_OK)
+    {
+        physaddr_t frame = reserve_page(kernel->page_stack);
+        status = frame % page_size;
+        if(status == S_OK)
+        {
+            status = map_page(kernel->page_stack, (void*)(location + n), frame, PAGE_USERMODE | PAGE_RW);
+            if(status != S_OK && free_page(kernel->page_stack, frame) != S_OK)
+            {
+                panic("critical error reached during mmap.");
+            }
+            n += page_size;
+        }
+        else
+        {
+            break;
+        }
+    }
+    if(status != S_OK && munmap(kernel, location, page_size, NULL) != S_OK)
+    {
+        panic("critical error reached during mmap.");
+    }
+    return status;
+}
+
+size_t munmap(struct kernel_t *kernel, size_t location, size_t length, size_t arg3)
+{
+    if(location % page_size != 0 || length % page_size != 0)
+    {
+        return S_INVALID_ARGUMENT;
+    }
+    else if(location == 0)
+    {
+        return S_NULL_POINTER;
+    }
+    size_t n = 0;
+    int status = S_OK;
+    while(n < length && status == S_OK)
+    {
+        enum page_type_t type = page_type((void*)(location + n));
+        physaddr_t frame;
+        if(type != PAGE_NOT_PRESENT)
+        {
+            frame = unmap_page((void*)(location + n));
+        }
+        if(type == PAGE_ANON)
+        {
+            status = free_page(kernel->page_stack, frame);
+        }
+    }
+    return status;
+}