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/****************************************************************************
* arch/x86/include/i486/arch.h
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/* This file should never be included directed but, rather,
* only indirectly through nuttx/arch.h
*/
#ifndef __ARCH_X86_INCLUDE_I486_ARCH_H
#define __ARCH_X86_INCLUDE_I486_ARCH_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#ifndef __ASSEMBLY__
# include <stdint.h>
#endif
/****************************************************************************
* Definitions
****************************************************************************/
/* FLAGS bits */
#define X86_FLAGS_CF (1 << 0) /* Bit 0: Carry Flag */
/* Bit 1: Reserved */
#define X86_FLAGS_PF (1 << 2) /* Bit 2: Parity Flag */
/* Bit 3: Reserved */
#define X86_FLAGS_AF (1 << 4) /* Bit 4: Auxillary carry Flag */
/* Bit 5: Reserved */
#define X86_FLAGS_ZF (1 << 6) /* Bit 6: Zero Flag */
#define X86_FLAGS_SF (1 << 7) /* Bit 7: Sign Flag */
#define X86_FLAGS_TF (1 << 8) /* Bit 8: Trap Flag */
#define X86_FLAGS_IF (1 << 9) /* Bit 9: Interrupt Flag */
#define X86_FLAGS_DF (1 << 10) /* Bit 10: Direction Flag */
#define X86_FLAGS_OF (1 << 11) /* Bit 11: Overflow Flag */
#define X86_FLAGS_IOPL_SHIFT (12) /* Bits 12-13: IOPL mask (286+ only)*/
#define X86_FLAGS_IOPL_MASK (3 << X86_FLAGS_IOPL_SHIFT)
#define X86_FLAGS_NT (1 << 14) /* Bit 14: Nested Task */
/* Bit 15: Reserved */
/* EFLAGS bits (Extend the basic FLAGS bit definitions) */
#define X86_EFLAGS_RF (1 << 16) /* Bit 16: Resume Flag (386+ only) */
#define X86_EFLAGS_VM (1 << 17) /* Bit 17: Virtual Mode (386+ only) */
#define X86_EFLAGS_AC (1 << 18) /* Bit 18: Alignment Check (486SX+ only) */
#define X86_EFLAGS_VIF (1 << 19) /* Bit 19: Virtual Interrupt Flag (Pentium+) */
#define X86_EFLAGS_VIP (1 << 20) /* Bit 20: Virtual Interrupt Pending (Pentium+) */
#define X86_EFLAGS_ID (1 << 21) /* Bit 21: CPUID detection flag (Pentium+) */
/****************************************************************************
* Public Types
****************************************************************************/
/* GDT data structures ******************************************************
*
* The Global Descriptor Table or GDT is a data structure used by Intel x86-
* family processors starting with the 80286 in order to define the
* characteristics of the various memory areas used during program execution,
* for example the base address, the size and access privileges like
* executability and writability. These memory areas are called segments in
* Intel terminology.
*/
/* This structure defines one segment */
struct gdt_entry_s
{
uint16_t lowlimit; /* The lower 16 bits of the limit */
uint16_t lowbase; /* The lower 16 bits of the base */
uint8_t midbase; /* The next 8 bits of the base */
uint8_t access; /* Access flags, determine ring segment can be used in */
uint8_t granularity;
uint8_t hibase; /* The last 8 bits of the base */
} __attribute__((packed));
/* This structure refers to the array of GDT entries, and is in the format
* required by the lgdt instruction.
*/
struct gdt_ptr_s
{
uint16_t limit; /* The upper 16 bits of all selector limits */
uint32_t base; /* The address of the first GDT entry */
} __attribute__((packed));
/* IDT data structures ******************************************************
*
* The Interrupt Descriptor Table (IDT) is a data structure used by the x86
* architecture to implement an interrupt vector table. The IDT is used by the
* processor to determine the correct response to interrupts and exceptions.
*/
struct idt_entry_s
{
uint16_t lobase; /* Lower 16-bits of vector address for interrupt */
uint16_t sel; /* Kernel segment selector */
uint8_t zero; /* This must always be zero */
uint8_t flags; /* (See documentation) */
uint16_t hibase; /* Upper 16-bits of vector address for interrupt */
} __attribute__((packed));
/* A struct describing a pointer to an array of interrupt handlers. This is
* in a format suitable for giving to 'lidt'.
*/
struct idt_ptr_s
{
uint16_t limit;
uint32_t base; /* The address of the first GDT entry */
} __attribute__((packed));
/****************************************************************************
* Inline functions
****************************************************************************/
#ifndef __ASSEMBLY__
/* Return stack pointer */
static inline uint32_t up_getsp()
{
uint32_t regval;
asm volatile(
"\tmovl %%esp, %0\n"
: "=rm" (regval)
:
: "memory");
return regval;
}
/* Get segment registers */
static inline uint32_t up_getds()
{
uint32_t regval;
asm volatile(
"\tmov %%ds, %0\n"
: "=rm" (regval)
:
: "memory");
return regval;
}
static inline uint32_t up_getcs()
{
uint32_t regval;
asm volatile(
"\tmov %%cs, %0\n"
: "=rm" (regval)
:
: "memory");
return regval;
}
static inline uint32_t up_getss()
{
uint32_t regval;
asm volatile(
"\tmov %%ss, %0\n"
: "=rm" (regval)
:
: "memory");
return regval;
}
/****************************************************************************
* Public Types
****************************************************************************/
/****************************************************************************
* Public Variables
****************************************************************************/
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
#ifdef __cplusplus
#define EXTERN extern "C"
extern "C" {
#else
#define EXTERN extern
#endif
EXTERN void gdt_flush(uint32_t gdt_addr);
EXTERN void idt_flush(uint32_t idt_addr);
#undef EXTERN
#ifdef __cplusplus
}
#endif
#endif /* __ASSEMBLY__ */
#endif /* __ARCH_X86_INCLUDE_I486_ARCH_H */
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