334 lines
9.3 KiB
C
334 lines
9.3 KiB
C
#include "assembly.h"
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#include <string.h>
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#include <stdlib.h>
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#include <stdio.h>
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// Max instruction width is 25 characters without the null char
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//
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// INSTRUCTIONS:
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// BYTE 3 BYTE 2 BYTE 1 BYTE 0
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// +===================================================+
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// | | | | |
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// +===================================================+
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//
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//
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// Exception:
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// The bytecode 0xFFFFFFFx is an invalid command
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// where x is any nibble
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//
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//
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// INSTRUCTION FORMAT 0:
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// +===================================================+
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// | OPCODE | 24 BIT IMMEDIATE ADDRESS |
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// +===================================================+
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//
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// INSTRUCTION FORMAT 1:
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// +===================================================+
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// | OPCODE | SOURCE REG | DEST REG |
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// +===================================================+
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//
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// INSTRUCTION FORMAT 2:
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// +===================================================+
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// | OPCODE | DEST REG | 16 BIT IMMEDIATE |
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// +===================================================+
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//
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//
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//
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// OPCODE FORMAT:
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// ______________________________________________________________________________________________________
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// |BIT | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
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// +----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
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// | | INSTR. FORMAT | 8bit opcode num : 16bit opcode num |
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// +----+-----------------+-----------------------------+-----------------------------------------------+
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//
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//
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// INSTRUCTION FORMAT 0 OPCODE NUM:
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// +-------+----------------------------------+--------------+
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// | NUM | DESCRIPTION | AFFECT FLAGS |
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// +-------+----------------------------------+--------------+
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// | 5'd0 | NOP | NO |
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// +-------+----------------------------------+--------------+
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// | 5'd1 | Unconditional Jump | NO |
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// +-------+----------------------------------+--------------+
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// | 5'd2 | Jump if zero flag is set | NO |
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// +-------+----------------------------------+--------------+
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// | 5'd3 | Jump if zero flag is not set | NO |
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// +-------+----------------------------------+--------------+
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// | 5'd4 | Jump if carry flag is set | NO |
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// +-------+----------------------------------+--------------+
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// | 5'd5 | Jump if carry flag is not set | NO |
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//
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//
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// INSTRUCTION FORMAT 1 OPCODE NUM:
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// +-------+----------------------------------+--------------+
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// | NUM | DESCRIPTION | AFFECT FLAGS |
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// +-------+----------------------------------+--------------+
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// | 13'd0 | ADD | YES |
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// +-------+----------------------------------+--------------|
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// | 13'd1 | SUBTRACT | YES |
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// +-------+----------------------------------+--------------|
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// | 13'd2 | SHIFT LEFT | YES |
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// +-------+----------------------------------+--------------|
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// | 13'd3 | SHIFT RIGHT | YES |
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// +-------+----------------------------------+--------------|
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// | 13'd4 | COMPARE (SUBTRACT WITHOUT SAVE) | YES |
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// +-------+----------------------------------+--------------+
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// | 13'd5 | HALT | NO |
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//
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//
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// INSTRUCTION FORMAT 2 OPCODE NUM:
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// +-------+----------------------------------------------+--------------+
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// | NUM | DESCRIPTION | AFFECT FLAGS |
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// +-------+----------------------------------------------+--------------+
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// | 5'd0 | MOV IMMEDIATE TO DEST LOW PART OF REGISTER | NO |
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// +-------+----------------------------------------------+--------------+
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// | 5'd1 | MOV IMMEDIATE TO DEST HIGH PART OF REGISTER | NO |
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#define MAX_INSTRUCTION_LENGTH 26
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char *disassemble(uint32_t opcode_be){
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uint32_t opcode=(opcode_be&0x000000FF)<<24|(opcode_be&0x0000FF00)<<8|(opcode_be&0x00FF0000)>>8|(opcode_be&0xFF000000)>>24;
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char *ret=malloc(MAX_INSTRUCTION_LENGTH);
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if (!ret)
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return NULL;
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//////// PARSE BITECODE //////////
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int instruction_format,opcode_num;
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uint32_t val;
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uint8_t val1;
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uint8_t val2;
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instruction_format=(opcode&0xE0000000)>>29;
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if(instruction_format==0){
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// 8bit opcode
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opcode_num=(opcode&0x1F000000)>>24;
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val=opcode&0x00FFFFFF;
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switch(opcode_num){
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case 0x00:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"NOP");
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break;
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case 0x01:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"JMP $%06X",val);
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break;
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case 0x02:
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case 0x03:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"JMP,%s $%06X",opcode_num&1?"NZ":"Z",val);
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break;
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case 0x04:
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case 0x05:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"JMP,%s $%06X",opcode_num&1?"NC":"C",val);
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break;
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default:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"UNRECOGNISED INSTR");
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break;
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}
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}else if(instruction_format==1){
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// 16bit opcode
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opcode_num=(opcode&0x1FFF0000)>>16;
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val1=(opcode&0x0000FF00)>>8;
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val2=opcode&0x000000FF;
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switch(opcode_num){
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case 0x00:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"ADD %%R%0d, %%R%0d",val1,val2);
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break;
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case 0x01:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"SUB %%R%0d, %%R%0d",val1,val2);
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break;
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case 0x02:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"SL %%R%0d",val1);
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break;
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case 0x03:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"SR %%R%0d",val1);
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break;
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case 0x04:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"CMP %%R%0d, %%R%0d",val1,val2);
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break;
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case 0x05:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"HALT");
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break;
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default:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"UNRECOGNISED INSTRUCTION");
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break;
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}
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}else if(instruction_format==2){
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// 16bit opcode
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opcode_num=(opcode&0x1F000000)>>24;
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val1=(opcode&0x00FF0000)>>16;
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val=opcode&0x0000FFFF;
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switch(opcode_num){
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case 0x00:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"MOV $%04X, %%R%0dl",val,val1);
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break;
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case 0x01:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"MOV $%04X, %%R%0dh",val,val1);
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break;
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default:
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"UNRECOGNISED INSTRUCTION");
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break;
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}
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}else
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snprintf(ret,MAX_INSTRUCTION_LENGTH,"UNRECOGNISED INSTRUCTION");
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return ret;
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}
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uint32_t assemble_line(char *line, __attribute__((unused)) struct assembler_context_t *assembler_context){
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uint16_t opcode;
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int x;
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if(strncmp(line,"JMP",3)==0){
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x=3;
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if(line[x]==' '){
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opcode=0x01;
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}else if(line[x]==','){
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x++;
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if(line[x]=='Z'){
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opcode=0x02;
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x++;
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}else if(line[x]=='C'){
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opcode=0x04;
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x++;
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}else if(line[x]=='N'){
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x++;
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if(line[x]=='Z'){
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opcode=0x03;
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x++;
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}else if(line[x]=='C'){
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opcode=0x05;
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x++;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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while(line[x]==' ')x++;
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uint32_t addr;
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if(line[x]=='$'){
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x++;
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if(sscanf(line+x,"%06X",&addr)!=1)
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return 0xFFFFFFFF;
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else
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return opcode<<24|(addr&0x00FFFFFF);
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}else
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return 0xFFFFFFFF;
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}else{
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uint8_t r1,r0,params;
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if(strncmp(line,"ADD",3)==0){
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x=3;
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opcode=0x2000;
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params=2;
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}else if(strncmp(line,"SUB",3)==0){
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x=3;
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opcode=0x2001;
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params=2;
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}else if(strncmp(line,"SL",2)==0){
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x=2;
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opcode=0x2002;
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params=1;
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}else if(strncmp(line,"SR",2)==0){
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x=2;
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opcode=0x2003;
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params=1;
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}else if(strncmp(line,"CMP",3)==0){
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x=3;
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opcode=0x2004;
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params=2;
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}else
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params=0;
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if(params!=0){
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while(line[x]==' ')x++;
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if(line[x]=='%'){
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x++;
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if(line[x]=='R'){
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x++;
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if(line[x]>='0'&&line[x]<='7'){
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r0=line[x]-'0';
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if(params==2){
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x++;
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while(line[x]==' ')x++;
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if(line[x]==','){
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x++;
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while(line[x]==' ')x++;
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if(line[x]=='%'){
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x++;
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if(line[x]=='R'){
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x++;
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if(line[x]>='0'&&line[x]<='7'){
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r1=line[x]-'0';
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return (opcode<<16)|r0<<8|r1;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else
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return (opcode<<16)|r0<<8;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else if(strncmp(line,"MOV",3)==0){
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uint32_t data;
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x=3;
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while(line[x]==' ')x++;
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if(line[x]=='$'){
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x++;
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if(sscanf(line+x,"%04X",&data)==1){
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x+=4;
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while(line[x]==' ')x++;
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if(line[x]==','){
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x++;
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while(line[x]==' ')x++;
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if(line[x]=='%'){
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x++;
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if(line[x]=='R'){
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x++;
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if(line[x]>='0'&&line[x]<='7'){
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r1=line[x]-'0';
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x++;
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if(line[x]=='l')
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return 0x40000000|r1<<16|data;
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else if(line[x]=='h')
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return 0x41000000|r1<<16|data;
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else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}else if(strncmp(line,"HALT",4)==0){
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x=4;
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while(line[x]==' ')x++;
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if(line[x]==0)
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return 0x20050000;
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else
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return 0xFFFFFFFF;
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}else
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return 0xFFFFFFFF;
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}
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}
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void free_assembler_context(struct assembler_context_t *tofree){
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free(tofree);
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}
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