+struct label_ *label_find_(struct dynamic_array *labels, char *name) {
+ size_t x;
+
+ for (x = 0; x < labels->entries; x++) {
+ struct label_ *l = (struct label_ *)DYNARRAY_ITEM(*labels, x);
+ if (strcmp(l->label, name) == 0)
+ return l;
+ }
+ return NULL;
+}
+
+
+/* if a label has a validly-calculated address, fetch it */
+static
+int label_addr_(struct dynamic_array *labels, char *name, DCPU16_WORD *addr) {
+ struct label_ *l;
+
+ if ( (l = label_find_(labels, name)) == NULL )
+ return -1;
+ if (! l->ready)
+ return -2;
+ *addr = l->addr;
+ return 0;
+}
+
+
+/* attempt to determine the addresses of all labels */
+static
+void label_addr_calculate_(struct dynamic_array *instructionps, struct dynamic_array *labels) {
+ size_t i;
+
+ /* idea: label1:label2 - calculated as offset between labels */
+
+ /* for each label.. */
+ for (i = 0; i < labels->entries; i++) {
+ struct label_ *l;
+ struct instruction_ **instr;
+ unsigned int word_count = 0;
+
+ l = (struct label_ *)DYNARRAY_ITEM(*labels, i);
+
+ DEBUG_PRINTFQ("%s: calculating address of label '%s'\n", __func__, l->label);
+
+#if 0
+force full resolution while debugging
+ /* if it's already calculated, great. */
+ if (l->ready)
+ continue;
+#endif
+
+ /*
+ * starting at the instruction for this label,
+ * walk backwards through the list of instructions
+ * until we get to the start or a known prior label address.
+ * update our label with the freshly calculated addr
+ */
+
+ /* first fetch the instruction associated with the label we want to know about.. */
+ /* the addr of this instruction will be whatever follows all the preceding instructions */
+ /* so back up one before counting instruction lengths... */
+ instr = ((struct label_ *)DYNARRAY_ITEM(*labels, i))->instr;
+ /* is it the first one? */
+ if (instr == (struct instruction_ **)DYNARRAY_ITEM(*instructionps, 0))
+ break;
+
+ instr--;
+
+ while (instr >= (struct instruction_ **)DYNARRAY_ITEM(*instructionps, 0)) {
+ if ((*instr)->ready == 0)
+ DEBUG_PRINTF("%s: instr '%s' not ready\n", __func__, (*instr)->opcode);
+ word_count += (*instr)->length;
+
+ DEBUG_PRINTF("%s: instr '%s' takes '%u' bytes\n", __func__, (*instr)->opcode, (*instr)->length);
+
+ /* have we come across an instruction which a label points to?
+ it should already be calculated, so just add that on and be done */
+ if ((*instr)->label
+ && strcmp((*instr)->label, l->label)) {
+ DCPU16_WORD addr;
+
+ if (label_addr_(labels, (*instr)->label, &addr)) {
+ fprintf(stderr, "internal error: incomplete prior address for '%s' while calculating '%s'\n",
+ (*instr)->label,
+ l->label);
+ continue;
+ }
+
+ word_count += addr;
+ break;
+ }
+ instr--;
+ }
+ l->addr = word_count;
+ l->ready = 1;
+ DEBUG_PRINTF("label '%s' now has addr of 0x%04x\n", l->label, word_count);
+ }
+}
+
+
+/* generate the nibble for a given basic opcode */
+static
+int opcode_bits_(char *opcode) {
+ static struct {
+ char op[4];
+ char value;
+ } opcodes_lower_nibble[] = {
+ { "JSR", 0x00 },
+ /* { "future nbi instruction", 0x00 }, */
+ { "SET", 0x01 },
+ { "ADD", 0x02 },
+ { "SUB", 0x03 },
+ { "MUL", 0x04 },
+ { "DIV", 0x05 },
+ { "MOD", 0x06 },
+ { "SHL", 0x07 },
+ { "SHR", 0x08 },
+ { "AND", 0x09 },
+ { "BOR", 0x0a },
+ { "XOR", 0x0b },
+ { "IFE", 0x0c },
+ { "IFN", 0x0d },
+ { "IFG", 0x0e },
+ { "IFB", 0x0f },
+ { "", 0x00 }
+ }, *o;
+
+ for (o = opcodes_lower_nibble; o->op[0]; o++) {
+ if (strcasecmp(o->op, opcode) == 0)
+ break;
+ }
+
+ if (o->op[0] == '\0') {
+ fprintf(stderr, "unknown instruction '%s'\n", opcode);
+ return -1;
+ }
+
+ return o->value;
+}
+
+/* generate the six bits for a given nbi opcode (aka first operand to opcode 0x00) */
+static
+int nbi_opcode_bits_(char *nbi_opcode) {
+ static struct {
+ char op[4];
+ char value;
+ } nbi_opcodes_bits[] = {
+ { " ", 0x00 }, /* reserved for future */
+ { "JSR", 0x01 },
+ { "", 0x00 }
+ }, *o;
+
+ for (o = nbi_opcodes_bits; o->op[0]; o++) {
+ if (strcasecmp(o->op, nbi_opcode) == 0)
+ break;
+ }
+
+ if (o->op[0] == '\0') {
+ fprintf(stderr, "unknown nbi instruction '%s'\n", o->op);
+ return -1;
+ }
+
+ return o->value;
+}
+
+/* convert register character like 'x' to value like 0x03 */
+static inline
+unsigned int register_enumerate_(char r) {
+ const char regs[] = "AaBbCcXxYyZzIiJj";
+ const char *x = strchr(regs, r);
+
+ if (x)
+ return (x - regs)/2;
+
+ fprintf(stderr, "internal error, unknown register character 0x%02x\n", r);
+ return -1;
+}
+
+/* removes all occurences of chars from buf */
+static inline
+void buf_strip_chars_(char *buf, char *chars) {
+ char *s, *d;
+
+ for (s = d = buf; *s; s++, d++) {
+ while (*s && strchr(chars, *s)) {
+ s++;
+ }
+ if (!*s)
+ break;
+ *d = *s;
+ }
+ *d = *s;
+}
+
+
+/* value_bits_
+ * generate the six bits for a given operand string
+ * returns -1 if it could not parse the operand
+ * returns -2 if it could not parse the operand due to an unresolved label
+ * notes: nextword may be overwritten even if it's not used in final instruction
+ */
+static
+int value_bits_(struct dynamic_array *labels, const char *operand_orig, DCPU16_WORD *nextword, unsigned int *nextwordused, unsigned int allow_short_labels) {
+ static char *operand = NULL;
+ static size_t operand_sz = 0;
+
+ unsigned long l;
+ char *o, *ep;
+
+ /*
+ Our operand working buffer shouldn't ever need to be too big,
+ but DAT might blow that assumption.
+ */
+ if (operand_sz <= strlen(operand_orig)) {
+ void *tmp_ptr;
+ size_t new_sz = strlen(operand_orig);
+
+ if (new_sz < 256)
+ new_sz = 256;
+ new_sz += 256;
+
+ DEBUG_PRINTF("%s: allocating buffer of size %zu\n", __func__, new_sz);
+ tmp_ptr = realloc(operand, new_sz);
+ if (tmp_ptr == NULL) {
+ fprintf(stderr, "%s(%zu):%s\n", "realloc", new_sz, strerror(errno));
+ return -1;
+ }
+ operand = tmp_ptr;
+ operand_sz = new_sz;
+ }
+
+ o = strcpy(operand, operand_orig);
+
+ DEBUG_PRINTF("%s: operand '%s' ", __func__, operand); /* completed later */
+
+ /* this is a very stupid parser */
+
+ /* first, let's trim all whitespace out of string at once to make parsing easier */
+ buf_strip_chars_(operand, " \t\n");
+
+ /* single character might match a register */
+ if (strlen(operand) == 1
+ && strchr("AaBbCcXxYyZzIiJj", *operand)) {
+ DEBUG_PRINTFQ("is register %c\n", *operand);
+ return register_enumerate_(*operand);
+ }
+
+ /* easy matches */
+ if (strcasecmp(operand, "POP") == 0) {
+ DEBUG_PRINTFQ("is POP\n");
+ return 0x18;
+ }
+ if (strcasecmp(operand, "PUSH") == 0) {
+ DEBUG_PRINTFQ("is PUSH\n");
+ return 0x19;
+ }
+ if (strcasecmp(operand, "PEEK") == 0) {
+ DEBUG_PRINTFQ("is PEEK\n");
+ return 0x1a;
+ }
+ if (strcasecmp(operand, "SP") == 0) {
+ DEBUG_PRINTFQ("is register SP\n");
+ return 0x1b;
+ }
+ if (strcasecmp(operand, "PC") == 0) {
+ DEBUG_PRINTFQ("is register PC\n");
+ return 0x1c;
+ }
+ if (strcasecmp(operand, "O") == 0) {
+ DEBUG_PRINTFQ("is register O\n");
+ return 0x1d;
+ }
+
+ /* is the operand [bracketed]? */
+ if (operand[0] == '[' && operand[strlen(operand) - 1] == ']') {
+ /* eat the brackets */
+ operand[strlen(operand) - 1] = '\0';
+ operand++;
+
+ /* is it [register]? */
+ if (strlen(operand) == 1
+ && strchr("AaBbCcXxYyZzIiJj", *operand)) {
+ DEBUG_PRINTFQ("is dereferenced register %c\n", *operand);
+ return 0x08 | register_enumerate_(*operand);
+ }
+
+ /* is it [register+something]? */
+ if ( (ep = strchr(operand, '+')) ) {
+ char *reg;
+ char *constant;