Added N_START

Author: U-UC\harvey1

src/as4.c

@@ -3,6 +3,7 @@
 /* This is the main file */
 
 unsigned long long FILELINE = 0;
+uint16_t N_START = 0xFFFF;
 
 /* Let's get ready to party */
 int main(int argc, char **argv)
@@ -306,6 +307,22 @@ int main(int argc, char **argv)
 								addinst(outbuf, NOP, address, &bits, &bytes);
 
 							}
+							/* Find where the N_ section starts */
+							else if(!strncmp(tokens, "NSTART", 7))
+							{
+								tokens = strtok(NULL, delims);
+								/* Check firstly that there is a valid label or address after the instruction. */
+								if(tokens == NULL || tokens[0] == '\n' || tokens[0] == '\r' || tokens[0] == '\0' || tokens[0] == ' ')
+								{
+									fprintf(stderr, "Line %llu: A memory address must succeed a DSEC instruction.\n", FILELINE);
+									exit(34);
+								}
+								/* Get the address location. */
+								/* If it's just a number after the instruction, that will be returned with the base address added to it. */
+								/* If it's a yet undeclared label, 65535 (UNKNOWNADDR) is returned. The instruction will be modified when the label is declared. */
+								/* If it's an already declared label return the address relative to the base address. */
+								N_START = findlabel(&unknownlabels, &labels, tokens, numlabels, &numunknownlabels, bits, INST);
+							}
 							/* Each group of same size data sections should be recorded with the pair DNUM DSIZE */
 							else if(!strncmp(tokens, "DNUM", 5))
 							{
@@ -357,9 +374,22 @@ int main(int argc, char **argv)
 								doneline = 1;
 								/* Just in case someone forgot EPINF... */
 								inpinf = 0;
-								/* Add it to the buffer. */
+								/* Prevent the address of EINF from getting written over... */
+								if(unknownlabels != NULL)
+								{
+									for(i = 0; i < numunknownlabels; i++)
+									{
+										if((unknownlabels[i].str != NULL) && (!strcmp(unknownlabels[i].str, "N_")) && (unknownlabels[i].addr == (bits/4)))
+										{
+											char *emptystr = calloc(1, 2);
+											memcpy(emptystr, "", 2);
+											unknownlabels[i].str = emptystr;
+											unknownlabels[i].addr = 0xFFFF;
+										}	
+									}
+								}
+								/* Add to output buffer. */
 								addinst(outbuf, NOP, 0xFFFF, &bits, &bytes);
-
 							}
 							/* Nand instruction. */
 							else if(!strncmp(tokens, "NND", 4))
@@ -593,7 +623,8 @@ int main(int argc, char **argv)
 					if(labels[j].str != NULL)
 					{
 						/* If we find it, set found to true. */
-						if(!strcmp(labels[j].str, unknownlabels[i].str))
+						/* if both str is "" and addr is 0xFFFF, this was an unknown label we were meant to ignore. */
+						if(!strcmp(labels[j].str, unknownlabels[i].str) || (!strcmp("", unknownlabels[i].str) && (unknownlabels[i].addr == 0xFFFF)))
 						{
 							foundunknown = 1;
 						}

src/as4.h

@@ -40,9 +40,13 @@
 /* When we are using labels references labels, we need account for the 4 nibble size instead of 5 for an instruction */
 #define INST 0
 #define LABEL 1
+#define ADDROF 2
 
-/* The singular global variable - what line of the assembly file we are on. Helps with error messages */
+/* What line of the assembly file we are on. Helps with error messages */
 extern unsigned long long FILELINE;
+/* Where the N_ section starts. Used for address-of operations. */
+extern uint16_t N_START;
+
 
 /* This is the data structure used to identify labels */
 typedef struct _label
@@ -51,6 +55,7 @@ typedef struct _label
 	char *str;
 	uint16_t offset;
 	uint8_t type;
+	uint16_t addroffset;
 } label;
 
 /* Help() prints the help. More useful in large programs */

src/label.c

@@ -78,6 +78,11 @@ void addlabel(char *outbuf, label **labels, label **unknownlabels, unsigned long
 	/* Assign the current location of the output buffer to as the address, because then the label will point to the next instruction or data element added, which is what we want. */
 	/* Also add the base address, which is important. */
 	(*labels)[(*numlabels) - 1].addr = ((bits/4) + baseaddr);
+	/* If the label is for N_, then don't add anything to the output buffer but set N_START. */
+	if(!(strcmp(tempstr, "N_")))
+	{
+		N_START = ((bits/4) + baseaddr);
+	}
 	/* Now we've saved the declared label, we can check for it being used before it was declared. */
 	/* But if there is no output buffer, we can't do much. */
 	if(outbuf == NULL)
@@ -94,7 +99,7 @@ void addlabel(char *outbuf, label **labels, label **unknownlabels, unsigned long
 			for(i = 0; i < numunknownlabels; i++)
 			{
 				/* If the unknown label name exits (otherwise it would be hard to identify it)... */
-				if((*unknownlabels)[i].str != NULL)
+				if((*unknownlabels)[i].str != NULL && strcmp((*unknownlabels)[i].str, ""))
 				{
 					/* Check if the name of the unknown label is the same as the label that we just had declared. */
 					if(!strcmp((*unknownlabels)[i].str, tempstr))