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#include "arch/kernel/main.hpp"
#include "arch/boot/pointers.hpp"
#include "arch/memory/multiboot.hpp"
#include "arch/video/vga/text.hpp"
namespace teachos::arch::kernel
{
auto assert(bool condition) -> void
{
video::vga::text::write("Assert failed", video::vga::text::common_attributes::green_on_black);
while (!condition)
{
// Trick the compiler into thinking the variable is changes at run time,
// to prevent the while loop being optimized away
// See
// https://stackoverflow.com/questions/9495856/how-to-prevent-g-from-optimizing-out-a-loop-controlled-by-a-variable-that-can
// for mroe information.
asm volatile("" : "+g"(condition));
}
}
auto print_mem_info(arch::memory::memory_info * mem_info) -> void
{
video::vga::text::write("Memory info low: ", video::vga::text::common_attributes::green_on_black);
video::vga::text::write_number(mem_info->mem_lower, video::vga::text::common_attributes::green_on_black);
}
auto print_memory_map(arch::memory::memory_map * mminfo) -> void
{
auto expected_entry_size = mminfo->entry_size;
constexpr auto actual_entry_size = sizeof(arch::memory::memory_area);
assert(expected_entry_size == actual_entry_size);
auto remaining_size = mminfo->tag.size - (4 * sizeof(uint32_t));
auto entry_amount = remaining_size / mminfo->entry_size;
auto begin = &mminfo->entries;
auto end = begin + entry_amount;
for (auto entry = begin; entry != end; ++entry)
{
video::vga::text::write("Looping Memory area", video::vga::text::common_attributes::green_on_black);
}
}
auto print_elf_sections(arch::memory::elf_symbols_section * symbol) -> void
{
auto expected_entry_size = symbol->entry_size;
constexpr auto actual_entry_size = sizeof(arch::memory::elf_section_header);
assert(expected_entry_size == actual_entry_size);
auto expected_total_size = symbol->tag.size;
auto actual_total_entry_size = actual_entry_size * symbol->number_of_sections;
constexpr auto actual_total_section_size =
sizeof(arch::memory::elf_symbols_section) - actual_entry_size - sizeof(uint32_t);
auto actual_total_size = actual_total_entry_size + actual_total_section_size;
assert(expected_total_size == actual_total_size);
auto begin = &symbol->sections;
auto end = begin + symbol->number_of_sections;
// TODO: Last value is completly wrong, should show 0 but shows huge value for size of entries in the table of the
// SHT_NULL elf section entry. Memory around value also make no sense and look even worse? But according to api
// value should be zero :(
// assert(begin->is_null());
// TODO: Check if only contains one DYNSYM or SYMTAB but not both!
// TODO: Check if only contains one dynamic section
for (auto section = begin; section != end; ++section)
{
video::vga::text::write("Looping Code section", video::vga::text::common_attributes::green_on_black);
}
}
auto main() -> void
{
using namespace video::vga;
text::clear();
text::cursor(false);
text::write("TeachOS is starting up...", text::common_attributes::green_on_black);
arch::memory::multi_boot_info * multiboot_information_pointer =
(arch::memory::multi_boot_info *)arch::boot::multiboot_information_pointer;
auto multiboot_tag = &(multiboot_information_pointer->tags);
/*
* Loop over the multiboot2 tags to access the information needed.
* Tags are defined in the header file and are padded so that each
* Tag starts at an 8-bytes aligned adress.
*
* The increment part aligns the size to an 8-byte address.
*/
for (auto tag = multiboot_tag; tag->type != arch::memory::multi_boot_tag_type::END;
tag = (arch::memory::multi_boot_tag *)(((uint8_t *)tag) + ((tag->size + 7) & ~7)))
{
switch (tag->type)
{
case arch::memory::multi_boot_tag_type::BASIC_MEMORY_INFO:
print_mem_info((arch::memory::memory_info *)tag);
break;
case arch::memory::multi_boot_tag_type::ELF_SECTIONS:
print_elf_sections((arch::memory::elf_symbols_section *)tag);
break;
case arch::memory::multi_boot_tag_type::MEMORY_MAP:
print_memory_map((arch::memory::memory_map *)tag);
break;
default:
// All other cases are not important and can be ignored
break;
}
}
}
} // namespace teachos::arch::kernel
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