exectos/xtoskrnl/hl/i686/cpufunc.c

/**
 * PROJECT:         ExectOS
 * COPYRIGHT:       See COPYING.md in the top level directory
 * FILE:            xtoskrnl/hl/i686/cpufunc.c
 * DESCRIPTION:     Routines to provide access to special i686 CPU instructions
 * DEVELOPERS:      Rafal Kupiec <belliash@codingworkshop.eu.org>
 */

#include "xtkmapi.h"


/**
 * Instructs the processor to clear the interrupt flag.
 *
 * @return This routine does not return any value.
 *
 * @since XT 1.0
 */
XTCDECL
VOID
HlClearInterruptFlag()
{
    asm volatile("cli");
}

/**
 * Retrieves a various amount of information about the CPU.
 *
 * @param Registers
 *        Supplies a pointer to the structure containing all the necessary registers and leafs for CPUID.
 *
 * @return TRUE if CPUID function could be executed, FALSE otherwise.
 *
 * @since XT 1.0
 */
XTCDECL
BOOLEAN
HlCpuId(IN OUT PCPUID_REGISTERS Registers)
{
    UINT32 MaxLeaf;

    /* Get highest function ID available */
    asm volatile("cpuid"
                 : "=a" (MaxLeaf)
                 : "a" (Registers->Leaf & 0x80000000)
                 : "rbx", "rcx", "rdx");

    /* Check if CPU supports this command */
    if(Registers->Leaf > MaxLeaf)
    {
        /* Cannot call it, return FALSE */
        return FALSE;
    }

    /* Execute CPUID function */
    asm volatile("cpuid"
                 : "=a" (Registers->Eax),
                 "=b" (Registers->Ebx),
                 "=c" (Registers->Ecx),
                 "=d" (Registers->Edx)
                 : "a" (Registers->Leaf),
                 "c" (Registers->SubLeaf));

    /* Return TRUE */
    return TRUE;
}

/**
 * Halts the central processing unit (CPU).
 *
 * @return This routine does not return any value.
 *
 * @since XT 1.0
 */
XTCDECL
VOID
HlHalt()
{
    while(TRUE)
    {
        asm volatile("hlt");
    }
}

/**
 * Reads the data from the specified I/O port.
 *
 * @param Port
 *        Specifies the port number in the range of 0-0xFFFF.
 *
 * @return The value read from the port.
 *
 * @since XT 1.0
 */
XTCDECL
UCHAR
HlIoPortInByte(IN USHORT Port)
{
    UCHAR Value;
    asm volatile("inb %1, %0"
                 : "=a"(Value)
                 : "Nd"(Port));
    return Value;
}

/**
 * Writes the data to the specified I/O port.
 *
 * @param Port
 *        Specifies the port number in the range of 0-0xFFFF.
 *
 * @param Value
 *        Supplies the value to write.
 *
 * @return This routine does not return any value.
 *
 * @since XT 1.0
 */
XTCDECL
VOID
HlIoPortOutByte(IN USHORT Port,
                IN UCHAR Value)
{
    asm volatile("outb %0, %1"
                 :
                 : "a"(Value),
                 "Nd"(Port));
}

/**
 * Reads the specified CPU control register and returns its value.
 *
 * @param ControlRegister
 *        Supplies a number of a control register which controls the general behavior of a CPU.
 *
 * @return The value stored in the control register.
 *
 * @since XT 1.0
 */
XTCDECL
ULONG_PTR
HlReadControlRegister(IN USHORT ControlRegister)
{
    ULONG_PTR Value;

    /* Read a value from specified CR register */
    switch(ControlRegister)
    {
        case 0:
            /* Read value from CR0 */
            asm volatile("mov %%cr0, %0"
                         : "=r" (Value)
                         :
                         : "memory");
            break;
        case 2:
            /* Read value from CR2 */
            asm volatile("mov %%cr2, %0"
                         : "=r" (Value)
                         :
                         : "memory");
            break;
        case 3:
            /* Read value from CR3 */
            asm volatile("mov %%cr3, %0"
                         : "=r" (Value)
                         :
                         : "memory");
            break;
        case 4:
            /* Read value from CR4 */
            asm volatile("mov %%cr4, %0"
                         : "=r" (Value)
                         :
                         : "memory");
            break;
        default:
            /* Invalid control register set */
            Value = 0;
            break;
    }

    /* Return value read from given CR register */
    return Value;
}

/**
 * Instructs the processor to set the interrupt flag.
 *
 * @return This routine does not return any value.
 *
 * @since XT 1.0
 */
XTCDECL
VOID
HlSetInterruptFlag()
{
    asm volatile("sti");
}

/**
 * Writes a value to the specified CPU control register.
 *
 * @param ControlRegister
 *        Supplies a number of a control register which controls the general behavior of a CPU.
 *
 * @param Value
 *        Suplies a value to write to the CR register.
 *
 * @return This routine does not return any value.
 *
 * @since XT 1.0
 */
XTCDECL
VOID
HlWriteControlRegister(IN USHORT ControlRegister,
                       IN UINT_PTR Value)
{
    /* Write a value into specified control register */
    switch(ControlRegister)
    {
        case 0:
            /* Write value to CR0 */
            asm volatile("mov %0, %%cr0"
                         :
                         : "r"(Value)
                         : "memory");
            break;
        case 2:
            /* Write value to CR2 */
            asm volatile("mov %0, %%cr2"
                         :
                         : "r"(Value)
                         : "memory");
            break;
        case 3:
            /* Write value to CR3 */
            asm volatile("mov %0, %%cr3"
                         :
                         : "r"(Value)
                         : "memory");
            break;
        case 4:
            /* Write value to CR4 */
            asm volatile("mov %0, %%cr4"
                         :
                         : "r"(Value)
                         : "memory");
            break;
    }
}