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disasm.cpp
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disasm.cpp
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#include <cstdio>
#include <cstring>
#include "disasm.h"
#include "memio.h"
uint32_t nameRegister( uint32_t r, char *outputBuffer )
{
outputBuffer[0] = 0;
if( r > 31 )
{
return 1;
}
if( r == 0 )
{
strcpy( outputBuffer, "zero" );
}
else if( r == 1 )
{
strcpy( outputBuffer, "ra" );
}
else if( r == 2 )
{
strcpy( outputBuffer, "sp" );
}
else if( r == 3 )
{
strcpy( outputBuffer, "gp" );
}
else if( r == 4 )
{
strcpy( outputBuffer, "tp" );
}
else if( ( r > 4 ) && ( r < 8 ) )
{
sprintf( outputBuffer, "t%d", r - 5 );
}
else if( r == 8 )
{
strcpy( outputBuffer, "s0" );
}
else if( r == 9 )
{
strcpy( outputBuffer, "s1" );
}
else if( ( r > 9 ) && ( r < 18 ) )
{
sprintf( outputBuffer, "a%d", r - 10 );
}
else if( ( r > 17 ) && ( r < 28 ) )
{
sprintf( outputBuffer, "s%d", r - 16 );
}
else if( r > 27 )
{
sprintf( outputBuffer, "t%d", r - 25 );
}
return 0;
}
static uint32_t decodeIStypeImm( uint32_t imm, char *outputBuffer )
{
int16_t extImm;
outputBuffer[0] = 0;
if( imm & 0b100000000000 )
{
extImm = 0b1111100000000000 | imm;
}
else
{
extImm = imm;
}
sprintf( outputBuffer, "%d", extImm );
return 0;
}
static uint32_t decodeBtypeImm( uint32_t imm, uint32_t pc, char *outputBuffer )
{
int16_t extImm;
outputBuffer[0] = 0;
if( imm & 0b1000000000000 )
{
extImm = 0b1111000000000000 | imm;
}
else
{
extImm = imm;
}
sprintf( outputBuffer, "0x%x", pc + extImm );
return 0;
}
static uint32_t decodeJtypeImm( uint32_t imm, uint32_t pc, char *outputBuffer )
{
int32_t extImm;
outputBuffer[0] = 0;
if( imm & 0b100000000000000000000 )
{
extImm = 0b11111111111100000000000000000000 | imm;
}
else
{
extImm = imm;
}
sprintf( outputBuffer, "0x%x", pc + extImm );
return 0;
}
uint32_t dsDisassemble( dsContext_t *ctx, char *outputBuffer )
{
uint32_t pc;
uint32_t instruction;
uint32_t iDecAux;
char regDName[8];
char regS1Name[8];
char regS2Name[8];
char immValue[32];
if( outputBuffer == NULL )
{
return 1;
}
if( ctx == NULL )
{
return 1;
}
outputBuffer[0] = 0;
ctx->pc = ctx->codeBufStartPc + ( ctx->codeBufIdx * 4 );
instruction = fetchData( ctx->pc );
ctx->instruction = instruction;
//ctx->codeBufIdx += 1;
//decode instruction
//common
ctx->opcode = instruction & 0b1111111;
ctx->rd = ( instruction >> 7 ) & 0b11111;
ctx->funct3 = ( instruction >> 12 ) & 0b111;
ctx->rs1 = ( instruction >> 15 ) & 0b11111;
ctx->rs2 = ( instruction >> 20 ) & 0b11111;
//R-type
ctx->rtFunct7 = ( instruction >> 25 ) & 0b1111111;
//I-type
ctx->itImm = ( instruction >> 20 ) & 0b111111111111;
//S-type
ctx->stImm = ( instruction >> 7 ) & 0b11111;
iDecAux = ( instruction >> 25 ) & 0b1111111;
ctx->stImm |= iDecAux << 5;
//B-type
iDecAux = ( instruction >> 7 ) & 0b1;
ctx->btImm = iDecAux << 11;
iDecAux = ( instruction >> 8 ) & 0b1111;
ctx->btImm |= iDecAux << 1;
iDecAux = ( instruction >> 25 ) & 0b111111;
ctx->btImm |= iDecAux << 5;
iDecAux = ( instruction >> 31 ) & 0b1;
ctx->btImm |= iDecAux << 12;
//U-type
ctx->utImm = instruction & 0b11111111111111111111000000000000;
//J-type
//33222222222211111111110000000000
//10987654321098765432109876543210
//21000000000111111111rrrrrooooooo
//00987654321198765432dddddccccccc
iDecAux = ( instruction >> 12 ) & 0b11111111;
ctx->jtImm = iDecAux << 12;
iDecAux = ( instruction >> 20 ) & 0b1;
ctx->jtImm |= iDecAux << 11;
iDecAux = ( instruction >> 21 ) & 0b1111111111;
ctx->jtImm |= iDecAux << 1;
iDecAux = ( instruction >> 31 ) & 0b1;
ctx->jtImm |= iDecAux << 20;
//decode opcodes
switch( ctx->opcode )
{
//RV32I
//R - type
case 0b0110011:
nameRegister( ctx->rd, regDName );
nameRegister( ctx->rs1, regS1Name );
nameRegister( ctx->rs2, regS2Name );
//RV32M
if( ctx->rtFunct7 == 0x01 )
{
switch( ctx->funct3 )
{
case 0x0:
sprintf( outputBuffer, "mul %s, %s, %s", regDName, regS1Name, regS2Name );
break;
case 0x1:
sprintf( outputBuffer, "mulh %s, %s, %s", regDName, regS1Name, regS2Name );
break;
case 0x2:
sprintf( outputBuffer, "mulsu %s, %s, %s", regDName, regS1Name, regS2Name );
break;
case 0x3:
sprintf( outputBuffer, "mulu %s, %s, %s", regDName, regS1Name, regS2Name );
break;
case 0x4:
sprintf( outputBuffer, "div %s, %s, %s", regDName, regS1Name, regS2Name );
break;
case 0x5:
sprintf( outputBuffer, "divu %s, %s, %s", regDName, regS1Name, regS2Name );
break;
case 0x6:
sprintf( outputBuffer, "rem %s, %s, %s", regDName, regS1Name, regS2Name );
break;
case 0x7:
sprintf( outputBuffer, "remu %s, %s, %s", regDName, regS1Name, regS2Name );
break;
}
}
else
{
//RV32I
switch( ctx->funct3 )
{
case 0x0:
if( ctx->rtFunct7 == 0x00 )
{
sprintf( outputBuffer, "add %s, %s, %s", regDName, regS1Name, regS2Name );
}else if( ctx->rtFunct7 == 0x20 )
{
sprintf( outputBuffer, "sub %s, %s, %s", regDName, regS1Name, regS2Name );
}
break;
case 0x4:
if( ctx->rtFunct7 == 0x00 )
{
sprintf( outputBuffer, "xor %s, %s, %s", regDName, regS1Name, regS2Name );
}
break;
case 0x6:
if( ctx->rtFunct7 == 0x00 )
{
sprintf( outputBuffer, "or %s, %s, %s", regDName, regS1Name, regS2Name );
}
break;
case 0x7:
if( ctx->rtFunct7 == 0x00 )
{
sprintf( outputBuffer, "and %s, %s, %s", regDName, regS1Name, regS2Name );
}
break;
case 0x1:
if( ctx->rtFunct7 == 0x00 )
{
sprintf( outputBuffer, "sll %s, %s, %s", regDName, regS1Name, regS2Name );
}
break;
case 0x5:
if( ctx->rtFunct7 == 0x00 )
{
sprintf( outputBuffer, "srl %s, %s, %s", regDName, regS1Name, regS2Name );
}else if( ctx->rtFunct7 == 0x20 )
{
sprintf( outputBuffer, "sra %s, %s, %s", regDName, regS1Name, regS2Name );
}
break;
case 0x2:
if( ctx->rtFunct7 == 0x00 )
{
sprintf( outputBuffer, "slt %s, %s, %s", regDName, regS1Name, regS2Name );
}
break;
case 0x3:
if( ctx->rtFunct7 == 0x00 )
{
sprintf( outputBuffer, "sltu %s, %s, %s", regDName, regS1Name, regS2Name );
}
break;
}
}
break;
//I - type
case 0b0010011:
nameRegister( ctx->rd, regDName );
nameRegister( ctx->rs1, regS1Name );
decodeIStypeImm( ctx->itImm, immValue );
switch( ctx-> funct3 )
{
case 0x0:
sprintf( outputBuffer, "addi %s, %s, %s", regDName, regS1Name, immValue );
break;
case 0x4:
sprintf( outputBuffer, "xori %s, %s, %s", regDName, regS1Name, immValue );
break;
case 0x6:
sprintf( outputBuffer, "ori %s, %s, %s", regDName, regS1Name, immValue );
break;
case 0x7:
sprintf( outputBuffer, "andi %s, %s, %s", regDName, regS1Name, immValue );
break;
case 0x1:
//todo: check if itImm(11 downto 5) are zeroes
sprintf( outputBuffer, "slli %s, %s, %d", regDName, regS1Name, ctx->itImm & 0xf );
break;
case 0x5:
//todo: do a proper check
if( ctx->itImm & 0xffe0 )
{
sprintf( outputBuffer, "srai %s, %s, %d", regDName, regS1Name, ctx->itImm & 0xf );
}
else
{
sprintf( outputBuffer, "srli %s, %s, %d", regDName, regS1Name, ctx->itImm & 0xf );
}
break;
case 0x2:
sprintf( outputBuffer, "slti %s, %s, %s", regDName, regS1Name, immValue );
break;
case 0x3:
sprintf( outputBuffer, "sltiu %s, %s, %s", regDName, regS1Name, immValue );
break;
}
break;
//I - type
case 0b0000011:
nameRegister( ctx->rd, regDName );
nameRegister( ctx->rs1, regS1Name );
decodeIStypeImm( ctx->itImm, immValue );
switch( ctx->funct3 )
{
case 0x0:
sprintf( outputBuffer, "lb %s, %s( %s )", regDName, immValue, regS1Name );
break;
case 0x1:
sprintf( outputBuffer, "lh %s, %s( %s )", regDName, immValue, regS1Name );
break;
case 0x2:
sprintf( outputBuffer, "lw %s, %s( %s )", regDName, immValue, regS1Name );
break;
case 0x4:
sprintf( outputBuffer, "lbu %s, %s( %s )", regDName, immValue, regS1Name );
break;
case 0x5:
sprintf( outputBuffer, "lhu %s, %s( %s )", regDName, immValue, regS1Name );
break;
}
break;
//S - type
case 0b0100011:
nameRegister( ctx->rs1, regS1Name );
nameRegister( ctx->rs2, regS2Name );
decodeIStypeImm( ctx->stImm, immValue );
switch( ctx->funct3 )
{
case 0x0:
sprintf( outputBuffer, "sb %s, %s( %s )", regS2Name, immValue, regS1Name );
break;
case 0x1:
sprintf( outputBuffer, "sh %s, %s( %s )", regS2Name, immValue, regS1Name );
break;
case 0x2:
sprintf( outputBuffer, "sw %s, %s( %s )", regS2Name, immValue, regS1Name );
break;
}
break;
//B - type
case 0b1100011:
nameRegister( ctx->rs1, regS1Name );
nameRegister( ctx->rs2, regS2Name );
decodeBtypeImm( ctx->btImm, ctx->pc, immValue );
switch( ctx->funct3 )
{
case 0x0:
sprintf( outputBuffer, "beq %s, %s, %s", regS1Name, regS2Name, immValue );
break;
case 0x1:
sprintf( outputBuffer, "bne %s, %s, %s", regS1Name, regS2Name, immValue );
break;
case 0x4:
sprintf( outputBuffer, "blt %s, %s, %s", regS1Name, regS2Name, immValue );
break;
case 0x5:
sprintf( outputBuffer, "bge %s, %s, %s", regS1Name, regS2Name, immValue );
break;
case 0x6:
sprintf( outputBuffer, "bltu %s, %s, %s", regS1Name, regS2Name, immValue );
break;
case 0x7:
sprintf( outputBuffer, "bgeu %s, %s, %s", regS1Name, regS2Name, immValue );
break;
}
break;
//J - type
case 0b1101111:
nameRegister( ctx->rd, regDName );
decodeJtypeImm( ctx->jtImm, ctx->pc, immValue );
sprintf( outputBuffer, "jal %s, %s", regDName, immValue );
break;
//I - type
case 0b1100111:
nameRegister( ctx->rd, regDName );
nameRegister( ctx->rs1, regS1Name );
decodeIStypeImm( ctx->itImm, immValue );
if( ctx->funct3 == 0x0 )
{
sprintf( outputBuffer, "jalr %s, %s, %s", regDName, regS1Name, immValue );
}
break;
//U - type
case 0b0110111:
nameRegister( ctx->rd, regDName );
sprintf( outputBuffer, "lui %s, %d [ 0x%x ]", regDName, ctx->utImm >> 12, ctx->utImm );
break;
//U - type
case 0b0010111:
nameRegister( ctx->rd, regDName );
sprintf( outputBuffer, "auipc %s, %d [ 0x%x ]", regDName, ctx->utImm >> 12, ctx->utImm );
break;
//I - type
case 0b1110011:
nameRegister( ctx->rd, regDName );
nameRegister( ctx->rs1, regS1Name );
switch( ctx->funct3 )
{
case 0x0:
switch( ctx->itImm )
{
case 0x0:
strcpy( outputBuffer, "ecall" );
break;
case 0x1:
strcpy( outputBuffer, "ebreak" );
break;
case 0b000100000010:
strcpy( outputBuffer, "sret" );
break;
case 0b001100000010:
strcpy( outputBuffer, "mret" );
break;
case 0b011100000010:
strcpy( outputBuffer, "mnret" );
break;
case 0b000100000101:
strcpy( outputBuffer, "wfi" );
break;
}
break;
case 0x1:
sprintf( outputBuffer, "csrrw %s, %d, %s", regDName, ctx->itImm, regS1Name );
break;
case 0x2:
sprintf( outputBuffer, "csrrs %s, %d, %s", regDName, ctx->itImm, regS1Name );
break;
case 0x3:
sprintf( outputBuffer, "csrrc %s, %d, %s", regDName, ctx->itImm, regS1Name );
break;
case 0x5:
sprintf( outputBuffer, "csrrwi %s, %d, %d", regDName, ctx->itImm, ctx->rs1 );
break;
case 0x6:
sprintf( outputBuffer, "csrrsi %s, %d, %d", regDName, ctx->itImm, ctx->rs1 );
break;
case 0x7:
sprintf( outputBuffer, "csrrci %s, %d, %d", regDName, ctx->itImm, ctx->rs1 );
break;
}
break;
}
return 0;
}