bsb1/boot/multiboot/data.cc

#include "boot/multiboot/data.h"

/*! \brief Multiboot Information Structure according to Specification
 * \see [Multiboot Specification]{@ref multiboot}
 */
struct multiboot_info {
  /*! \brief Helper Structure
   */
  struct Array {
    uint32_t size;  ///< Length
    uint32_t addr;  ///< Begin (physical address)
  } __attribute__((packed));

  enum Flag : uint32_t {
    Memory = 1 << 0,   ///< is there basic lower/upper memory information?
    BootDev = 1 << 1,  ///< is there a boot device set?
    CmdLine = 1 << 2,  ///< is the command-line defined?
    Modules = 1 << 3,  ///< are there modules to do something with?
    /* These next two are mutually exclusive */
    SymbolTable = 1 << 4,    ///< is there an a.out symbol table loaded?
    SectionHeader = 1 << 5,  ///< is there an ELF section header table?

    MemoryMap = 1 << 6,       ///< is there a full memory map?
    DriveInfo = 1 << 7,       ///< Is there drive info?
    ConfigTable = 1 << 8,     ///< Is there a config table?
    BootLoaderName = 1 << 9,  ///< Is there a boot loader name?
    ApmTable = 1 << 10,       ///< Is there a APM table?

    // Is there video information?
    VbeInfo = 1 << 11,         ///< Vesa bios extension
    FramebufferInfo = 1 << 12  ///< Framebuffer
  } flags;

  /*! \brief Available memory retrieved from BIOS
   */
  struct {
    uint32_t lower;  ///< Amount of memory below 1 MiB in kilobytes
    uint32_t upper;  ///< Amount of memory above 1 MiB in kilobytes
  } mem __attribute__((packed));
  uint32_t boot_device;  ///< "root" partition
  uint32_t cmdline;      ///< Kernel command line
  Array mods;            ///< List of boot modules
  union {
    /*! \brief Symbol table for kernel in a.out format
     */
    struct {
      uint32_t tabsize;
      uint32_t strsize;
      uint32_t addr;
      uint32_t reserved;
    } aout_symbol_table __attribute__((packed));

    /*! \brief Section header table for kernel in ELF
     */
    struct {
      uint32_t num;    ///< Number of entries
      uint32_t size;   ///< Size per entry
      uint32_t addr;   ///< Start of the header table
      uint32_t shndx;  ///< String table index
    } elf_section_header_table __attribute__((packed));
  };

  struct Array mmap;          ///< Memory Map
  struct Array drives;        ///< Drive Information
  uint32_t config_table;      ///< ROM configuration table
  uint32_t boot_loader_name;  ///< Boot Loader Name
  uint32_t apm_table;         ///< APM table

  struct Multiboot::VBE vbe;                  ///< VBE Information
  struct Multiboot::Framebuffer framebuffer;  ///< Framebuffer information

  /*! \brief Check if setting is available
   * \param flag Flag to check
   * \return `true` if available
   */
  bool has(enum Flag flag) const { return (flags & flag) != 0; }
} __attribute__((packed));
assert_size(multiboot_info, 116);

/*! \brief The pointer to the multiboot structures will be assigned in the
 * assembler startup code (multiboot.inc)
 */
struct multiboot_info *multiboot_addr = 0;

namespace Multiboot {
Module *getModule(unsigned i) {
  if (multiboot_addr != nullptr &&
      multiboot_addr->has(multiboot_info::Flag::Modules) &&
      i < multiboot_addr->mods.size) {
    return i + reinterpret_cast<Module *>(
                   static_cast<uintptr_t>(multiboot_addr->mods.addr));
  } else {
    return nullptr;
  }
}

unsigned getModuleCount() { return multiboot_addr->mods.size; }

void *Memory::getStartAddress() const {
  if (sizeof(void *) == 4 && (addr >> 32) != 0) {
    return reinterpret_cast<void *>(addr & 0xffffffff);
  } else {
    return reinterpret_cast<void *>(static_cast<uintptr_t>(addr));
  }
}

void *Memory::getEndAddress() const {
  uint64_t end = addr + len;
  if (sizeof(void *) == 4 && (end >> 32) != 0) {
    return reinterpret_cast<void *>(addr & 0xffffffff);
  } else {
    return reinterpret_cast<void *>(static_cast<uintptr_t>(end));
  }
}

bool Memory::isAvailable() const { return type == AVAILABLE; }

Memory *Memory::getNext() const {
  if (multiboot_addr != nullptr &&
      multiboot_addr->has(multiboot_info::Flag::MemoryMap)) {
    uintptr_t next = reinterpret_cast<uintptr_t>(this) + size + sizeof(size);
    if (next < multiboot_addr->mmap.addr + multiboot_addr->mmap.size) {
      return reinterpret_cast<Memory *>(next);
    }
  }
  return nullptr;
}

Memory *getMemoryMap() {
  if (multiboot_addr != nullptr &&
      multiboot_addr->has(multiboot_info::Flag::MemoryMap) &&
      multiboot_addr->mmap.size > 0) {
    return reinterpret_cast<Memory *>(
        static_cast<uintptr_t>(multiboot_addr->mmap.addr));
  } else {
    return nullptr;
  }
}

char *getCommandLine() {
  return reinterpret_cast<char *>(
      static_cast<uintptr_t>(multiboot_addr->cmdline));
}

char *getBootLoader() {
  return reinterpret_cast<char *>(
      static_cast<uintptr_t>(multiboot_addr->boot_loader_name));
}

VBE *getVesaBiosExtensionInfo() {
  if (multiboot_addr != nullptr &&
      multiboot_addr->has(multiboot_info::Flag::VbeInfo)) {
    return &(multiboot_addr->vbe);
  } else {
    return nullptr;
  }
}

Framebuffer *getFramebufferInfo() {
  if (multiboot_addr != nullptr &&
      multiboot_addr->has(multiboot_info::Flag::FramebufferInfo)) {
    return &(multiboot_addr->framebuffer);
  } else {
    return nullptr;
  }
}
}  // namespace Multiboot