Commit: 4d828c8878ac64dfaab024b72c18fc8087a18e2e - motonesas (git)

MOT6502 assembler, disassembler and linker

Commit MetaInfo

• Revisión: 4d828c8878ac64dfaab024b72c18fc8087a18e2e (tree)
• Tiempo: 2013-02-08 20:21:00
• Autor: astoria-d <astoria-d@my-s...>
• Commiter: astoria-d

Log Message

assembler addressing mode fix.
now hello world assembler is verified.

Cambiar Resumen

• modified: assembler/6502inst.c
• modified: assembler/nesas.y
• modified: assembler/segment.c

Diferencia incremental

--- a/assembler/6502inst.c
+++ b/assembler/6502inst.c
@@ -17,6 +17,8 @@ struct instmap {
 #define NUM_ALPHA 'Z' - 'A' + 1
 #define ALPHA_INDEX(ch) ch - 'A'
 
+#define ROM_START   0x8000
+
 /* 
  * 6502 instructions
  * adressing mode        instruction length
@@ -128,6 +130,10 @@ int get_rel_addr(unsigned short abs_addr) {
     return (int) abs_addr - get_current_pc() ;
 }
 
+int get_abs_addr(unsigned short abs_addr) {
+    return (int) abs_addr + ROM_START ;
+}
+
 /*
  * returns the length of opcode.
  * returns 0 if invalid.
@@ -388,11 +394,13 @@ static void deb_print_str(const char* str) {
 }
 
 void write_str(const char* str) {
+    //dprint("write_str:%s\n", str);
     int len = strlen(str) + 1;
     FILE* fp = get_current_file();
+    char* p = str;
     while (len-- > 0)
         fwrite(str++, 1, 1, fp);
-    deb_print_str(str);
+    deb_print_str(p);
     move_current_pc(len);
 }
 

--- a/assembler/nesas.y
+++ b/assembler/nesas.y
@@ -15,6 +15,7 @@ char* cur_inst;
 int dir_data_size = 0;
 
 void add_unresolved_ref(const char* symbol);
+int get_abs_addr(unsigned short abs_addr);
 
 #if 1
 #define dprint(...)    
@@ -205,6 +206,12 @@ inst_param
         unsigned short addr = 0;
         int num = 0;
 
+
+        /*
+           ex)
+            lda     palettes, x
+         */
+         
         //second parameter is either X or Y.
         if (strcasecmp($<str>3, "X") && strcasecmp($<str>3, "Y")) {
             parser_perror("invalid parameter\n", $<str>3);
@@ -218,11 +225,13 @@ inst_param
         param = PARAM_NUM;
         ch = toupper(*$<str>3);
         param |= (ch == 'X' ? PARAM_INDEX_X : PARAM_INDEX_Y);
-        if (addr_lookup($<str>1, &addr)) 
-            num = get_rel_addr(addr);
+        if (addr_lookup($<str>1, &addr))  {
+            //reladdr from the next instruction.
+            num = get_rel_addr(addr) - 2;
+        }
         else {
             add_unresolved_ref($<str>1);
-            num = addr;
+            num = 0xFFFF;
         }
 
         if (!write_inst(cur_inst, param, num)) {
@@ -288,12 +297,28 @@ inst_param
         unsigned short addr = 0;
         int num = 0;
 
+        /*
+         ex)
+        mainloop:
+         jmp mainloop
+         bne mainloop
+         */
+
         dprint("%s\n", $<str>1);
-        if (addr_lookup($<str>1, &addr)) 
-            num = get_rel_addr(addr);
+        if (addr_lookup($<str>1, &addr)) { 
+            //set operand assocating with the instruction's addressing mode
+            //(relative or absolute).
+            if (!strcasecmp(cur_inst, "JMP") || !strcasecmp(cur_inst, "JSR")) {
+                num = get_abs_addr(addr);
+            }
+            else {
+                //reladdr from the next instruction.
+                num = get_rel_addr(addr) - 2;
+            }
+        }
         else {
             add_unresolved_ref($<str>1);
-            num = addr;
+            num = 0xFFFF;
         }
 
         if (!write_inst(cur_inst, PARAM_NUM, num)) {

--- a/assembler/segment.c
+++ b/assembler/segment.c
@@ -24,6 +24,7 @@ const char* get_out_fname(void);
 void molf_header_create(FILE* fp, unsigned short seg_cnt);
 void seg_header_create(FILE* fp, struct seginfo* seg);
 int set_seg_header_pos(FILE* fp, struct seginfo* seg, unsigned short start);
+int get_abs_addr(unsigned short abs_addr);
 
 int add_symbol (const char* symbol) {
     struct symmap *psym, *pp;
@@ -70,7 +71,9 @@ void add_unresolved_ref(const char* symbol) {
     unres_sym = malloc(sizeof (struct symmap));
     dlist_init(&unres_sym->list);
     unres_sym->symbol = strdup(symbol);
-    unres_sym->addr = pseg->current_pc;
+    //current_pc points to the current instruction.
+    //referece is next to the pc
+    unres_sym->addr = pseg->current_pc + 1;
 
     if (pseg->unresolved_symbol == NULL) {
         pseg->unresolved_symbol = unres_sym;
@@ -91,6 +94,8 @@ int addr_lookup(const char* symbol, unsigned short* return_addr) {
         struct symmap* pp = psym;
 
         if (!strcmp(symbol, psym->symbol)) {
+            dprint("addr_lookup %s found %04x, current:%08x\n", psym->symbol, 
+                    psym->addr, get_current_pc());
             found = TRUE;
             *return_addr = psym->addr;
             break;
@@ -257,9 +262,10 @@ int finalize_segment(void) {
                         //address offset is too far!
                         return FALSE;
                     }
-                    /*dprint("symbol ref at %04x to %s(%04x) resolved, %04x.\n", 
-                            unres->addr, unres->symbol, addr, addr - unres->addr);*/
-                    fseek(fp, addr - unres->addr, SEEK_SET);
+                    addr = get_abs_addr(addr);
+                    dprint("symbol ref at %04x to %s resolved, %04x.\n", 
+                            unres->addr, unres->symbol, addr);/**/
+                    fseek(fp, unres->addr, SEEK_SET);
                     fwrite(&addr, 2, 1, fp);
                 }
                 unres = (struct symmap*) unres->list.next;