195 lines
3.9 KiB
C
195 lines
3.9 KiB
C
#include "vm.h"
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#define DEBUG true;
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/* Load program tape into Memory */
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void load_program(struct lilith* vm, char **argv)
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{
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FILE* program;
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program = fopen(argv[1], "r");
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/* Figure out how much we need to load */
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fseek(program, 0, SEEK_END);
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size_t end = ftell(program);
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rewind(program);
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/* Load the entire tape into memory */
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fread(vm->memory, 1, end, program);
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fclose(program);
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}
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/* Load instruction addressed at IP */
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void read_instruction(struct lilith* vm, struct Instruction *current)
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{
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memset(current, 0, sizeof(struct Instruction));
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/* Store IP for debugging */
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current->ip = vm->ip;
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/* Read the actual bytes and increment the IP */
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current->raw0 = (uint8_t)vm->memory[vm->ip];
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vm->ip = vm->ip + 1;
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current->raw1 = (uint8_t)vm->memory[vm->ip];
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vm->ip = vm->ip + 1;
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current->raw2 = (uint8_t)vm->memory[vm->ip];
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vm->ip = vm->ip + 1;
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current->raw3 = (uint8_t)vm->memory[vm->ip];
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vm->ip = vm->ip + 1;
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unpack_instruction(current);
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}
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/* Process 4OP Integer instructions */
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bool eval_4OP_Int(struct lilith* vm, struct Instruction* c)
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{
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return true;
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}
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/* Process 3OP Integer instructions */
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bool eval_3OP_Int(struct lilith* vm, struct Instruction* c)
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{
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switch(c->raw_XOP)
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{
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case 0x000: /* ADD */
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{
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vm->reg[c->reg0] = vm->reg[c->reg1] + vm->reg[c->reg2];
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break;
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}
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default: return true;
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}
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return false;
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}
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/* Process 2OP Integer instructions */
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bool eval_2OP_Int(struct lilith* vm, struct Instruction* c)
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{
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return true;
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}
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/* Process 1OP Integer instructions */
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bool eval_1OP_Int(struct lilith* vm, struct Instruction* c)
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{
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return true;
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}
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/* Process 2OPI Integer instructions */
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bool eval_2OPI_Int(struct lilith* vm, struct Instruction* c)
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{
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/* 0x0E ... 0x2B */
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switch(c->raw0)
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{
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case 0x0E: /* ADDI */
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{
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vm->reg[c->reg0] = (int8_t)(vm->reg[c->reg1] + c->raw_Immediate);
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break;
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}
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case 0x0F: /* ADDUI */
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{
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vm->reg[c->reg0] = vm->reg[c->reg1] + c->raw_Immediate; break;
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}
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default: return true;
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}
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return false;
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}
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/* Use Opcode to decide what to do and then have it done */
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void eval_instruction(struct lilith* vm, struct Instruction* current)
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{
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bool invalid = false;
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switch(current->raw0)
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{
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case 0x00: /* Deal with NOPs */
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{
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vm->halted = true;
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return;
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}
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case 0x01:
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{
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decode_4OP(current);
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invalid = eval_4OP_Int(vm, current);
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if ( invalid) goto fail;
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break;
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}
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case 0x05:
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{
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decode_3OP(current);
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invalid = eval_3OP_Int(vm, current);
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if ( invalid) goto fail;
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break;
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}
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case 0x09:
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{
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decode_2OP(current);
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invalid = eval_2OP_Int(vm, current);
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if ( invalid) goto fail;
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break;
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}
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case 0x0D:
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{
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decode_1OP(current);
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invalid = eval_1OP_Int(vm, current);
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if ( invalid) goto fail;
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break;
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}
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case 0x0E ... 0x2B:
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{
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decode_2OPI(current);
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invalid = eval_2OPI_Int(vm, current);
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if ( invalid) goto fail;
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break;
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}
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case 0x2C:
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{
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}
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case 0x3C:
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{
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}
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case 0x42:
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{
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}
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case 0xFF: /* Deal with illegal instruction */
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default:
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{
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fail:
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fprintf(stderr, "Unable to execute the following instruction:\n%c %c %c %c\n", current->raw0, current->raw1, current->raw2, current->raw3);
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fprintf(stderr, "%s\n", current->operation);
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current->invalid = true;
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break;
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}
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}
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}
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void execute_vm(struct lilith* vm)
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{
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struct Instruction* current;
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current = calloc(1, sizeof(struct Instruction));
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while(!vm->halted)
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{
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read_instruction(vm, current);
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eval_instruction(vm, current);
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}
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free(current);
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return;
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}
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/* Standard C main program */
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int main(int argc, char **argv)
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{
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/* Make sure we have a program tape to run */
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if (argc < 2)
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{
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fprintf(stderr, "Usage: %s $FileName\nWhere $FileName is the name of the paper tape of the program being run\n", argv[0]);
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return EXIT_FAILURE;
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}
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/* Perform all the essential stages in order */
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struct lilith* vm;
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vm = create_vm(1 << 20);
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load_program(vm, argv);
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execute_vm(vm);
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destroy_vm(vm);
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return EXIT_SUCCESS;
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}
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