arm_emu.c File Reference

#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include "dbg_msg.h"
#include "arm_emu.h"
#include "jt_arm.h"
#include "jt_instr.h"

Defines

#define OK 1
#define FAIL 0
#define WRONG -1
#define GET_S_BIT(_S_bit_,_INSTR_)
#define GET_VZN_FLAGS
#define GET_C_FLAG
#define GET_VALUE_FROM_CPU_REGISTER(_VAL_, _RN_)
#define THUMB_GET_VALUE_FROM_CPU_LOW_REGISTER(_VAL_, _RN_)
#define THUMB_GET_VALUE_FROM_CPU_HIGH_REGISTER(_VAL_, _RN_)

Functions

static void arm_update_flags (void)
void arm_recalculate_flags_Z_N (uint32_t val)
uint32_t arm_emu_add (uint32_t l_val, uint32_t r_val, int carry_in)
uint32_t arm_emu_sub (uint32_t l_val, uint32_t r_val, int borrow_in)
uint32_t arm_emu_lsl (uint32_t sh_val, uint32_t imm, int fetch_c_flag)
uint32_t arm_emu_lsr (uint32_t sh_val, uint32_t imm, int fetch_c_flag)
uint32_t arm_emu_asr (uint32_t sh_val, uint32_t imm, int fetch_c_flag)
uint32_t arm_emu_ror (uint32_t rot_val, uint32_t imm, int fetch_c_flag, int with_carry)
static int arm_emu_opcode (int opcode, int rd, int rn, uint32_t l_op_val, uint32_t r_op_val, int S_bit)
int arm_step_emu (uint32_t instr)
int thumb_step_emu (uint16_t instr)

Variables

struct armEmuFlags armEmuFlags

Detailed Description

Define Documentation

#define OK 1

Referenced by arm_emu_opcode(), arm_step_emu(), and thumb_step_emu().

#define FAIL 0

Referenced by arm_step_emu(), and thumb_step_emu().

#define WRONG -1

Referenced by arm_emu_opcode().

#define GET_S_BIT	(	_S_bit_,
		_INSTR_		)

Referenced by arm_step_emu().

#define GET_VZN_FLAGS

Referenced by arm_step_emu(), and thumb_step_emu().

#define GET_C_FLAG

Referenced by arm_emu_asr(), arm_emu_lsl(), arm_emu_lsr(), arm_emu_ror(), arm_step_emu(), and thumb_step_emu().

#define GET_VALUE_FROM_CPU_REGISTER	(	_VAL_,
		_RN_		)

Referenced by arm_step_emu().

#define THUMB_GET_VALUE_FROM_CPU_LOW_REGISTER	(	_VAL_,
		_RN_		)

Referenced by thumb_step_emu().

#define THUMB_GET_VALUE_FROM_CPU_HIGH_REGISTER	(	_VAL_,
		_RN_		)

Referenced by thumb_step_emu().

Function Documentation

static void arm_update_flags ( void ) [static]

update all CPSR Flags

Returns:: -

References armEmuFlags::carry, reg_set::CPSR, CPU, CPU_CPSR_FLAG_CARRY, CPU_CPSR_FLAG_NEGATIVE, CPU_CPSR_FLAG_OVERFLOW, CPU_CPSR_FLAG_ZERO, armEmuFlags::negative, armEmuFlags::overflow, and armEmuFlags::zero.

Referenced by arm_emu_opcode(), arm_step_emu(), and thumb_step_emu().

void arm_recalculate_flags_Z_N ( uint32_t val )

recalculate Z and N flags (for CPSR)

Returns:: -

References armEmuFlags::negative, and armEmuFlags::zero.

Referenced by arm_emu_add(), arm_emu_opcode(), arm_emu_sub(), arm_step_emu(), doCmdSequence(), and thumb_step_emu().

uint32_t arm_emu_add	(	uint32_t	l_val,
		uint32_t	r_val,
		int	carry_in
	)

 calculate add: l_val + r_val 
 and recalculate global flags:
 overflow, carry, zero and negative
 2 bit adder
   00   00   00   00
 + 00   01   10   11
 = 00   01   10   11

   01   01   01   01
 + 00   01   10   11
 = 01   10v  11  c00

   10   10   10   10
 + 00   01   10   11
 = 10   11  c00v c01v

   11   11   11   11
 + 00   01   10   11
 = 11  c00  c01v c10

Parameters:

	l_val	:= left 32 bit value
	r_val	:= right 32 bit value
	carry_in	flag (0 or 1)

Returns:: result of l_val + r_val

References arm_recalculate_flags_Z_N(), armEmuFlags::carry, armEmuFlags::negative, and armEmuFlags::overflow.

Referenced by arm_emu_opcode(), doCmdSequence(), and thumb_step_emu().

uint32_t arm_emu_sub	(	uint32_t	l_val,
		uint32_t	r_val,
		int	borrow_in
	)

calculate sub: l_val - r_val and recalculate global flags: overflow, carry, zero and negative 2 bit subtracter 00 00 00 00

00 01 10 11 = 00 b11 b10v b01

01 01 01 01

00 01 10 11 = 01 00 b11v b10v

10 10 10 10

00 01 10 11 = 10 01v 00 b11

11 11 11 11

00 01 10 11 = 11 10 01 00

Parameters:

	l_val	:= left 32 bit value
	r_val	:= right 32 bit value
	borrow_in	flag (0 or 1)

Returns:: result of l_val - r_val

References arm_recalculate_flags_Z_N(), armEmuFlags::carry, armEmuFlags::negative, and armEmuFlags::overflow.

Referenced by arm_emu_opcode(), doCmdSequence(), and thumb_step_emu().

uint32_t arm_emu_lsl	(	uint32_t	sh_val,
		uint32_t	imm,
		int	fetch_c_flag
	)

logical shift left

Parameters:

	sh_val	value to be shifted
	imm	number of bit to shift
	fetch_c_flag	fetch previous carry flag from CPSR (if needed)

Returns:: = sh_val << imm

References armEmuFlags::carry, and GET_C_FLAG.

Referenced by arm_step_emu(), doCmdSequence(), and thumb_step_emu().

uint32_t arm_emu_lsr	(	uint32_t	sh_val,
		uint32_t	imm,
		int	fetch_c_flag
	)

logical shift right

Parameters:

	sh_val	value to be shifted
	imm	number of bit to shift
	fetch_c_flag	fetch previous carry flag from CPSR (if needed)

Returns:: = sh_val >> imm

References armEmuFlags::carry, and GET_C_FLAG.

Referenced by arm_step_emu(), doCmdSequence(), and thumb_step_emu().

uint32_t arm_emu_asr	(	uint32_t	sh_val,
		uint32_t	imm,
		int	fetch_c_flag
	)

arithmetic shift right

Parameters:

	sh_val	value to be shifted
	imm	number of bit to shift
	fetch_c_flag	fetch previous carry flag from CPSR (if needed)

Returns:: = sh_val >> imm

References armEmuFlags::carry, and GET_C_FLAG.

Referenced by arm_step_emu(), and thumb_step_emu().

uint32_t arm_emu_ror	(	uint32_t	rot_val,
		uint32_t	imm,
		int	fetch_c_flag,
		int	with_carry
	)

rotate right

Parameters:

	rot_val	value to be rotated
	imm	number of bit to rotate
	fetch_c_flag	fetch previous carry flag from CPSR (if needed)
	with_carry	imm == 32 use carry bit as bit 33 and rotate one position

Returns:: rotated value

References armEmuFlags::carry, and GET_C_FLAG.

Referenced by arm_step_emu(), doCmdSequence(), and thumb_step_emu().

static int arm_emu_opcode	(	int	opcode,
		int	rd,
		int	rn,
		uint32_t	l_op_val,
		uint32_t	r_op_val,
		int	S_bit
	)			`[static]`

ARM Opcode data processing

Parameters:

	opcode	one of the 15-ARM opcodes (AND,OR,ADD,SUB..)
	rd	number of the destination register
	rn
	l_op_val
	r_op_val
	S_bit	if S Bit set then update CPSR

Return values:

	0	OK
	-1	WRONG

References arm_emu_add(), arm_emu_sub(), arm_recalculate_flags_Z_N(), arm_update_flags(), armEmuFlags::carry, CPU, OK, reg_set::Regs::r, reg_set::regs, and WRONG.

Referenced by arm_step_emu().

int arm_step_emu ( uint32_t instr )

Try to emulate an ARM-instruction step. Only a small subset is supported.

Parameters:

instr

32-bit ARM instruction

Return values:

	1	OK if CPU changed
	0	FAIL if failed to change CPU

References arm_emu_asr(), arm_emu_lsl(), arm_emu_lsr(), arm_emu_opcode(), arm_emu_ror(), arm_recalculate_flags_Z_N(), arm_update_flags(), armEmuFlags::carry, CPU, FAIL, GET_C_FLAG, GET_S_BIT, GET_VALUE_FROM_CPU_REGISTER, GET_VZN_FLAGS, jt_arm_condition_pass(), armEmuFlags::negative, OK, reg_set::Regs::r, reg_set::regs, and armEmuFlags::zero.

Referenced by gdb_action_step(), and jtag_test().

int thumb_step_emu ( uint16_t instr )

Try to emulate an THUMB-instruction step. Only a small subset is supported. Some instructions are like bl and bx are already handled.

Parameters:

instr

16-bit THUMB instruction

Return values:

	1	OK if emulation succeed and CPU register changed
	0	FAIL if faild to change CPU

References arm_emu_add(), arm_emu_asr(), arm_emu_lsl(), arm_emu_lsr(), arm_emu_ror(), arm_emu_sub(), arm_recalculate_flags_Z_N(), arm_update_flags(), armEmuFlags::carry, CPU, FAIL, GET_C_FLAG, GET_VZN_FLAGS, jt_arm_condition_pass(), OK, reg_set::Regs::r, reg_set::regs, THUMB_GET_VALUE_FROM_CPU_HIGH_REGISTER, and THUMB_GET_VALUE_FROM_CPU_LOW_REGISTER.

Referenced by gdb_action_step(), jtag_arm9_Step(), and jtag_test().

Variable Documentation

struct armEmuFlags armEmuFlags