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ASM: Wrote the start of the definition for the ISA and some of the disassembly logic

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(Tim) Efthimis Kritikos 2024-01-31 18:28:36 +00:00
parent 651e875c9b
commit 3ff187824c
2 changed files with 161 additions and 8 deletions
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165
assembly.c
View File

@ -1,17 +1,170 @@
#include "assembly.h"
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
// Max instruction width is 25 characters without the null char
//
// INSTRUCTIONS:
// BYTE 3 BYTE 2 BYTE 1 BYTE 0
// +===================================================+
// | | | | |
// +===================================================+
//
//
//
// INSTRUCTION FORMAT 0:
// +===================================================+
// | OPCODE | 24 BIT IMMEDIATE ADDRESS |
// +===================================================+
//
// INSTRUCTION FORMAT 1:
// +===================================================+
// | OPCODE | SOURCE REG | DEST REG |
// +===================================================+
//
// INSTRUCTION FORMAT 2:
// +===================================================+
// | OPCODE | DEST REG | 16 BIT IMMEDIATE |
// +===================================================+
//
//
//
// OPCODE FORMAT:
// ______________________________________________________________________________________________________
// |BIT | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
// +----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
// | | INSTR. FORMAT | 8bit opcode num : 16bit opcode num |
// +----+-----------------+-----------------------------+-----------------------------------------------+
//
//
// INSTRUCTION FORMAT 0 OPCODE NUM:
// +-------+----------------------------------+--------------+
// | NUM | DESCRIPTION | AFFECT FLAGS |
// +-------+----------------------------------+--------------+
// | 5'd0 | NOP | NO |
// +-------+----------------------------------+--------------+
// | 5'd1 | Unconditional Jump | NO |
// +-------+----------------------------------+--------------+
// | 5'd2 | Jump if zero flag is set | NO |
// +-------+----------------------------------+--------------+
// | 5'd3 | Jump if zero flag is not set | NO |
// +-------+----------------------------------+--------------+
// | 5'd4 | Jump if carry flag is set | NO |
// +-------+----------------------------------+--------------+
// | 5'd5 | Jump if carry flag is not set | NO |
//
//
// INSTRUCTION FORMAT 1 OPCODE NUM:
// +-------+----------------------------------+--------------+
// | NUM | DESCRIPTION | AFFECT FLAGS |
// +-------+----------------------------------+--------------+
// | 13'd0 | ADD | YES |
// +-------+----------------------------------+--------------|
// | 13'd1 | SUBTRACT | YES |
// +-------+----------------------------------+--------------|
// | 13'd2 | SHIFT LEFT | YES |
// +-------+----------------------------------+--------------|
// | 13'd3 | SHIFT RIGHT | YES |
// +-------+----------------------------------+--------------|
// | 13'd4 | COMPARE (SUBTRACT WITHOUT SAVE) | YES |
//
//
// INSTRUCTION FORMAT 2 OPCODE NUM:
// +-------+----------------------------------------------+--------------+
// | NUM | DESCRIPTION | AFFECT FLAGS |
// +-------+----------------------------------------------+--------------+
// | 5'd0 | MOV IMMEDIATE TO DEST LOW PART OF REGISTER | NO |
// +-------+----------------------------------------------+--------------+
// | 5'd1 | MOV IMMEDIATE TO DEST HIGH PART OF REGISTER | NO |
#define MAX_INSTRUCTION_LENGTH 26
char *disassemble(uint32_t opcode_be){
uint32_t opcode=(opcode_be&0x000000FF)<<24|(opcode_be&0x0000FF00)<<8|(opcode_be&0x00FF0000)>>8|(opcode_be&0xFF000000)>>24;
char *ret=malloc(MAX_INSTRUCTION_LENGTH);
char *disassemble(uint32_t opcode){
char *ret=malloc(26);
if (!ret)
return NULL;
if(opcode!=0x01ABCDEF)
memcpy(ret,"placeholder",12);
else
memcpy(ret,"easter egg",11);
//////// PARSE BITECODE //////////
int instruction_format,opcode_num;
uint32_t val;
uint8_t val1;
uint8_t val2;
instruction_format=(opcode&0xE0000000)>>29;
if(instruction_format==0){
// 8bit opcode
opcode_num=(opcode&0x1F000000)>>24;
val=opcode&0x00FFFFFF;
switch(opcode_num){
case 0x00:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"NOP");
break;
case 0x01:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"JMP $%06X",val);
break;
case 0x02:
case 0x03:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"JMP %s,$%06X",opcode_num&1?"Z":"NZ",val);
break;
case 0x04:
case 0x05:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"JMP %s,$%06X",opcode_num&1?"C":"NC",val);
break;
default:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"UNRECOGNISED INSTR");
break;
}
}else if(instruction_format==1){
// 16bit opcode
opcode_num=(opcode&0x1FFF0000)>>16;
val1=(opcode&0x0000FF00)>>8;
val2=opcode&0x000000FF;
switch(opcode_num){
case 0x00:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"ADD %%R%0d, %%R%0d",val1,val2);
break;
case 0x01:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"SUB %%R%0d, %%R%0d",val1,val2);
break;
case 0x02:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"SL %%R%0d",val1);
break;
case 0x03:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"SR %%R%0d",val1);
break;
case 0x04:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"CMP %%R%0d, %%R%0d",val1,val2);
break;
default:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"UNRECOGNISED INSTRUCTION");
break;
}
}else if(instruction_format==2){
// 16bit opcode
opcode_num=(opcode&0x1FFF0000)>>16;
val1=(opcode&0x00FF0000)>>16;
val=opcode&0x0000FFFF;
switch(opcode_num){
case 0x00:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"MOV $%04X, %%R%0dl",val,val1);
break;
case 0x01:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"MOV $%04X, %%R%0dh",val,val1);
break;
default:
snprintf(ret,MAX_INSTRUCTION_LENGTH,"UNRECOGNISED INSTRUCTION");
break;
}
}else
snprintf(ret,MAX_INSTRUCTION_LENGTH,"UNRECOGNISED INSTRUCTION");
return ret;
}

4
gui.c
View File

@ -182,7 +182,7 @@ int update_general_disas(struct simdata_t *simdata){
if(width<18){
mvwprintw(general_disas,1,1,"too small window");
}else{
uint32_t ADDRESS=(simdata->PC-(height/2-2)*3)&0x00FFFFFF;
uint32_t ADDRESS=(simdata->PC-(height/2-2)*4)&0x00FFFFFF;
for (int i=2;i<height-2;i++){
int overall_offset=offset_arrow-2;
@ -199,7 +199,7 @@ int update_general_disas(struct simdata_t *simdata){
if(ADDRESS==simdata->PC)
wattroff(general_disas,A_BOLD);
ADDRESS=(ADDRESS+3)&0xFFFFFF;
ADDRESS=(ADDRESS+4)&0xFFFFFF;
free(disas);
}
mvwaddch(general_disas,height/2,offset_arrow,ACS_RARROW);