388 lines
9.6 KiB
C
388 lines
9.6 KiB
C
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/* Assembler code fragment for LC-2K */
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#define MAXLINELENGTH 1000
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int readAndParse(FILE *, char *, char *, char *, char *, char *);
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int isNumber(char *, int *);
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typedef struct{
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char *word;
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unsigned int hash;
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int line_number;
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} Label;
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typedef struct{
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char *word_space;
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char *word_cursor;
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Label *labels;
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int count;
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int max;
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} Table;
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char *
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copy_advance(char *dest, char *src){
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while (*dest++ = *src++);
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return(dest);
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}
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int
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get_hash(char *string){
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unsigned int x, c;
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x = 5236;
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while (c = *string++){
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x += c + (x << 5) + (x << 1);
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}
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return(x);
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}
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int
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add_label(Table *table, char *string, int line_number){
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int r;
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Label l, *ls;
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int max;
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unsigned int index;
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r = 0;
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max = table->max;
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ls = table->labels;
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l.word = table->word_cursor;
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table->word_cursor = copy_advance(table->word_cursor, string);
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l.hash = get_hash(string);
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l.line_number = line_number;
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index = l.hash % max;
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while (ls[index].word){
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if (ls[index].hash == l.hash){
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if (strcmp(ls[index].word, l.word) == 0){
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r = 1;
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break;
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}
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}
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index = (index + 1) % max;
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}
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if (r == 0) ls[index] = l;
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++table->count;
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return(r);
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}
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int
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find_label(Table *table, char *string, int *line_number){
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int r;
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Label l, *ls;
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int max;
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unsigned int hash,index;
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r = 0;
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max = table->max;
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ls = table->labels;
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hash = get_hash(string);
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index = hash % max;
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while (ls[index].word){
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if (ls[index].hash == hash){
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if (strcmp(ls[index].word, string) == 0){
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r = 1;
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*line_number = ls[index].line_number;
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break;
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}
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}
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index = (index + 1) % max;
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}
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return(r);
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}
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#define OP_FILL -1
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#define OP_ADD 0
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#define OP_NAND 1
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#define OP_LW 2
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#define OP_SW 3
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#define OP_BEQ 4
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#define OP_JALR 5
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#define OP_HALT 6
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#define OP_NOOP 7
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#define MIN16S -32768
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#define MAX16S 32767
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int
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encode_insanity(FILE *outFilePtr, int o, int a, int b, int c){
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int ins, r;
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r = 0;
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if (o == OP_FILL){
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r = (b != 0 || c != 0);
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}
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else{
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r = (a < 0 || a > 7 || b < 0 || b > 7);
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if (!r){
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switch (o){
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case OP_ADD: case OP_NAND:
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r = (c < 0 || c > 7); break;
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case OP_LW: case OP_SW:
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case OP_BEQ: case OP_JALR:
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r = (c < MIN16S || c > MAX16S); break;
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case OP_HALT: case OP_NOOP:
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r = (a != 0 || b != 0 || c != 0); break;
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default: r = 1; break;
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}
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}
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}
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if (!r){
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if (o == OP_FILL){
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ins = a;
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}
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else{
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ins = 0;
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ins |= (o << 22);
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ins |= (a << 19);
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ins |= (b << 16);
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ins |= 0xFFFF & (c);
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}
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fprintf(outFilePtr, "%d\n", ins);
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}
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return(r);
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}
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int
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main(int argc, char *argv[])
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{
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Table table;
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char *inFileString, *outFileString;
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FILE *inFilePtr, *outFilePtr;
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char label[MAXLINELENGTH], opcode[MAXLINELENGTH], arg0[MAXLINELENGTH],
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arg1[MAXLINELENGTH], arg2[MAXLINELENGTH];
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int max_instructions;
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int line_number;
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int i;
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int o,a,b,c;
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if (argc != 3) {
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printf("error: usage: %s <assembly-code-file> <machine-code-file>\n",
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argv[0]);
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exit(1);
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}
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inFileString = argv[1];
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outFileString = argv[2];
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inFilePtr = fopen(inFileString, "r");
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if (inFilePtr == NULL) {
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printf("error in opening %s\n", inFileString);
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exit(1);
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}
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outFilePtr = fopen(outFileString, "w");
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if (outFilePtr == NULL) {
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printf("error in opening %s\n", outFileString);
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exit(1);
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}
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fseek(inFilePtr, 0, SEEK_END);
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max_instructions = ftell(inFilePtr);
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fseek(inFilePtr, 0, SEEK_SET);
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max_instructions >>= 2;
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table.max = max_instructions * 3 / 2;
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table.labels = (Label*)malloc(sizeof(Label)*table.max);
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table.count = 0;
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table.word_space = table.word_cursor = (char*)malloc((max_instructions << 2) + max_instructions);
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memset(table.labels, 0, sizeof(Label)*table.max);
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line_number = 0;
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while (readAndParse(inFilePtr, label, opcode, arg0, arg1, arg2)){
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if (*label != 0){
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if (add_label(&table, label, line_number)){
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printf("error two labels of same name: %s\n", label);
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exit(1);
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}
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}
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++line_number;
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}
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rewind(inFilePtr);
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line_number = 0;
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while (readAndParse(inFilePtr, label, opcode, arg0, arg1, arg2)){
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if (strcmp(opcode, "add") == 0){
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o = 0;
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sscanf(arg0, "%d", &a);
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sscanf(arg1, "%d", &b);
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sscanf(arg2, "%d", &c);
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}
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else if (strcmp(opcode, "nand") == 0){
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o = 1;
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sscanf(arg0, "%d", &a);
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sscanf(arg1, "%d", &b);
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sscanf(arg2, "%d", &c);
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}
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else if (strcmp(opcode, "lw") == 0){
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o = 2;
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sscanf(arg0, "%d", &a);
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sscanf(arg1, "%d", &b);
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if (!isNumber(arg2, &c)){
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if (!find_label(&table, arg2, &c)){
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printf("non-existant label: %s\n", arg2);
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exit(1);
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}
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}
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}
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else if (strcmp(opcode, "sw") == 0){
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o = 3;
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sscanf(arg0, "%d", &a);
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sscanf(arg1, "%d", &b);
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if (!isNumber(arg2, &c)){
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if (!find_label(&table, arg2, &c)){
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printf("non-existant label: %s\n", arg2);
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exit(1);
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}
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}
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}
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else if (strcmp(opcode, "beq") == 0){
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o = 4;
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sscanf(arg0, "%d", &a);
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sscanf(arg1, "%d", &b);
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if (!isNumber(arg2, &c)){
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if (!find_label(&table, arg2, &c)){
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printf("non-existant label: %s\n", arg2);
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exit(1);
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}
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c = c - (line_number + 1);
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}
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}
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else if (strcmp(opcode, "jalr") == 0){
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o = 5;
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sscanf(arg0, "%d", &a);
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sscanf(arg1, "%d", &b);
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c = 0;
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}
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else if (strcmp(opcode, "halt") == 0){
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o = 6;
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a = b = c = 0;
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}
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else if (strcmp(opcode, "noop") == 0){
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o = 7;
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a = b = c = 0;
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}
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else if (strcmp(opcode, ".fill") == 0){
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o = -1;
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if (!isNumber(arg0, &a)){
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if (!find_label(&table, arg0, &a)){
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printf("non-existant label: %s\n", arg0);
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exit(1);
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}
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}
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b = c = 0;
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}
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else{
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printf("not real instruction found: %s\n", opcode);
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exit(1);
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}
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if (encode_insanity(outFilePtr, o, a, b, c)){
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printf("encoding error on line %d\n", line_number + 1);
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exit(1);
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}
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++line_number;
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}
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free(table.word_space);
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free(table.labels);
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fclose(inFilePtr);
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fclose(outFilePtr);
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exit(0);
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return(0);
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}
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/*
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* Read and parse a line of the assembly-language file. Fields are returned
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* in label, opcode, arg0, arg1, arg2 (these strings must have memory already
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* allocated to them).
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*
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* Return values:
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* 0 if reached end of file
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* 1 if all went well
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*
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* exit(1) if line is too long.
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*/
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int
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readAndParse(FILE *inFilePtr, char *label, char *opcode, char *arg0,
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char *arg1, char *arg2)
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{
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char line[MAXLINELENGTH + 1];
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char *ptr = line;
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int l;
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/* delete prior values */
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label[0] = opcode[0] = arg0[0] = arg1[0] = arg2[0] = '\0';
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/* read the line from the assembly-language file */
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if (fgets(line, MAXLINELENGTH, inFilePtr) == NULL) {
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/* reached end of file */
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return(0);
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}
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if (feof(inFilePtr)){
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l = strlen(line);
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if (line[l-1] != '\n'){
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line[l] = '\n';
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line[l+1] = 0;
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}
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}
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#if 0
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char line[MAXLINELENGTH];
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char *ptr = line;
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/* delete prior values */
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label[0] = opcode[0] = arg0[0] = arg1[0] = arg2[0] = '\0';
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/* read the line from the assembly-language file */
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if (fgets(line, MAXLINELENGTH, inFilePtr) == NULL) {
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/* reached end of file */
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return(0);
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}
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#endif
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/* check for line too long (by looking for a \n) */
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if (strchr(line, '\n') == NULL) {
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/* line too long */
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printf("error: line too long\n");
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exit(1);
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}
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/* is there a label? */
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ptr = line;
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if (sscanf(ptr, "%[^\t\n\r ]", label)) {
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/* successfully read label; advance pointer over the label */
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ptr += strlen(label);
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}
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/*
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* Parse the rest of the line. Would be nice to have real regular
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* expressions, but scanf will suffice.
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*/
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sscanf(ptr, "%*[\t\n\r ]%[^\t\n\r ]%*[\t\n\r ]%[^\t\n\r ]%*[\t\n\r ]%[^\t\n\r ]%*[\t\n\r ]%[^\t\n\r ]",
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opcode, arg0, arg1, arg2);
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return(1);
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}
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int
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isNumber(char *string, int *i)
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{
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return( (sscanf(string, "%d", i)) == 1);
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}
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