Implelent proper defines

As oppossed to labels to arbitraty addresses.

This also prepares the way to support calculated values.

2 files changed, 102 insertions, 65 deletions

diff --git a/README.md b/README.md
index f8eb7e5..79d4049 100644
--- a/README.md
+++ b/README.md
@@ -287,8 +287,8 @@ and `>`for the high byte.
 .dw imm [, imm]  
 Literal word (16-bit value).
 
-.equ label imm  
-Define a label assigning an arbitrary immediate. Because it is a label, the value will be 16-bit unless `<` or `>` are used.
+.equ id value  
+Define an ID assigning a constant value. When the id is used, it will be replaced with its value.
 
 .include "filename"  
 Assemble the file at current position.
diff --git a/tr8as.c b/tr8as.c
index 29ef45c..aa5439d 100644
--- a/tr8as.c
+++ b/tr8as.c
@@ -35,6 +35,7 @@
 #define MAX_ID 0x40
 #define MAX_LABELS 0x200
 #define MAX_REFS 0x1000
+#define MAX_DEFS 0x200
 
 #define FHH 2
 #define FHL 1
@@ -71,6 +72,13 @@ typedef struct
 
 typedef struct
 {
+    char id[MAX_ID + 1];
+    char value[MAX_ID + 1];
+    Location loc;
+} Define;
+
+typedef struct
+{
     uint8_t out[UINT16_MAX + 1];
     size_t size;
 
@@ -82,6 +90,9 @@ typedef struct
 
     Reference refs[MAX_REFS];
     uint16_t rcnt;
+
+    Define defs[MAX_DEFS];
+    uint16_t dcnt;
 } As;
 
 typedef struct
@@ -166,6 +177,39 @@ static uint8_t isspecial(char c)
     return c == '$' || c == '_' || c == '.' || c == '#' || c == '<' || c == '>';
 }
 
+static char * find_define(As *as, char *word, char *found)
+{
+    uint8_t i;
+
+    for (i = 0; i < as->dcnt; i++)
+        if (!strcmp(word, as->defs[i].id))
+            return find_define(as, as->defs[i].value, as->defs[i].value);
+
+    return found;
+}
+
+static uint8_t new_define(As *as, char *id, char *value)
+{
+    if (find_define(as, id, NULL))
+        return error_l("Id redefined", &as->loc, id);
+
+    value = find_define(as, value, value);
+
+    if (!strcmp(id, value))
+        return error_l("Recursive definition", &as->loc, id);
+
+    strcpy(as->defs[as->dcnt].id, id);
+    strcpy(as->defs[as->dcnt].value, value);
+
+    as->defs[as->dcnt].loc.filename = as->loc.filename;
+    as->defs[as->dcnt++].loc.line = as->loc.line;
+
+    if (as->dcnt == MAX_DEFS)
+        return error("Too many definitions", NULL);
+
+    return 1;
+}
+
 static uint8_t next_word(As *as, char **c, char *word, uint8_t *wlen)
 {
     *c = skip_whitespace(*c);
@@ -187,10 +231,28 @@ static uint8_t next_word(As *as, char **c, char *word, uint8_t *wlen)
     return 1;
 }
 
-static uint8_t next_imm(char *word, uint16_t *n)
+static uint8_t next_imm(As *as, char *word, uint16_t *n)
 {
+    Mod mod = ModNone;
+    char *def;
+
     *n = 0;
 
+    if (*word == '<')
+    {
+        mod = ModLow;
+        word++;
+    }
+    else if (*word == '>')
+    {
+        mod = ModHigh;
+        word++;
+    }
+
+    def = find_define(as, word, NULL);
+    if (def)
+        word = def;
+
     if (*word == '0')
     {
         /* hex */
@@ -210,7 +272,7 @@ static uint8_t next_imm(char *word, uint16_t *n)
 
                 word++;
             }
-            return *word;
+            goto done;
         }
         /* bin */
         else if (word[1] == 'b')
@@ -225,7 +287,7 @@ static uint8_t next_imm(char *word, uint16_t *n)
 
                 word++;
             }
-            return *word;
+            goto done;
         }
     }
 
@@ -240,7 +302,18 @@ static uint8_t next_imm(char *word, uint16_t *n)
         word++;
     }
 
-    return *word;
+done:
+    if (*word == 0)
+    {
+        if (mod == ModLow)
+            *n &= 0xff;
+        else if (mod == ModHigh)
+            *n >>= 8;
+
+        return 1;
+    }
+
+    return 0;
 }
 
 static uint8_t parse_register(char *word)
@@ -285,15 +358,6 @@ static uint8_t new_label(As *as, char *word)
     return 1;
 }
 
-static uint8_t new_label_imm(As *as, char *word, uint16_t imm)
-{
-    if (!new_label(as, word))
-        return 1;
-
-    as->labels[as->lcnt - 1].addr = imm;
-    return 1;
-}
-
 static uint8_t new_ref(As *as, char *word, uint16_t mask, uint16_t addr)
 {
     Mod mod = ModNone;
@@ -405,7 +469,7 @@ static uint8_t parse_org(As *as, char **c)
     if (wlen == 0)
         return error_l("Syntax error", &as->loc, "expected immediate");
 
-    if (next_imm(word, &as->addr))
+    if (!next_imm(as, word, &as->addr))
         return error_l("Syntax error", &as->loc, word);
 
     if (as->addr > as->size)
@@ -573,29 +637,25 @@ static uint8_t parse_incbin(As *as, char **c)
 
 static uint8_t parse_equ(As *as, char **c)
 {
-    char label[MAX_ID + 1];
-    char word[MAX_ID + 1];
+    char id[MAX_ID + 1];
+    char value[MAX_ID + 1];
     uint8_t wlen;
-    uint16_t imm;
 
     /* .equ label imm */
 
-    if (!next_word(as, c, label, &wlen))
+    if (!next_word(as, c, id, &wlen))
         return 0;
 
     if (wlen == 0)
-        return error_l("Syntax error", &as->loc, "expected label");
+        return error_l("Syntax error", &as->loc, "expected id");
 
-    if (!next_word(as, c, word, &wlen))
+    if (!next_word(as, c, value, &wlen))
         return 0;
 
     if (wlen == 0)
-        return error_l("Syntax error", &as->loc, "expected immediate");
+        return error_l("Syntax error", &as->loc, "expected value");
 
-    if (next_imm(word, &imm))
-        return error_l("Syntax error", &as->loc, word);
-
-    return new_label_imm(as, label, imm);
+    return new_define(as, id, value);
 }
 
 static uint8_t parse_db(As *as, char **c)
@@ -614,11 +674,8 @@ static uint8_t parse_db(As *as, char **c)
         if (wlen == 0)
             return error_l("Syntax error", &as->loc, "expected immediate");
 
-        if (isdigit(*word))
+        if (next_imm(as, word, &imm))
         {
-            if (next_imm(word, &imm))
-                return error_l("Syntax error", &as->loc, word);
-
             if (imm > 0xff)
                 return error_l("Overflow in immediate", &as->loc, word);
         }
@@ -656,11 +713,8 @@ static uint8_t parse_dw(As *as, char **c)
         if (wlen == 0)
             return error_l("Syntax error", &as->loc, "expected immediate");
 
-        if (isdigit(*word))
-        {
-            if (next_imm(word, &imm))
-                return error_l("Syntax error", &as->loc, word);
-        }
+        if (next_imm(as, word, &imm))
+            return error_l("Syntax error", &as->loc, word);
         else if (!new_ref(as, word, 0xffff, as->addr))
             return 0;
 
@@ -773,11 +827,8 @@ static uint8_t parse_r1_r2_or_imm(As *as, char **c, uint8_t *r1, uint8_t *r2, ui
         return 1;
 
     /* ? r1, imm */
-    if (isdigit(*word))
+    if (next_imm(as, word, imm))
     {
-        if (next_imm(word, imm))
-            return error_l("Syntax error", &as->loc, word);
-
         if (*imm > 0xff)
             return error_l("Overflow in immediate", &as->loc, word);
     }
@@ -818,7 +869,7 @@ static uint8_t parse_r1_imm(As *as, char **c, uint8_t *r1, uint16_t *imm)
     if (!isdigit(*word))
         return error_l("Syntax error", &as->loc, "expected immediate");
 
-    if (next_imm(word, imm))
+    if (!next_imm(as, word, imm))
         return error_l("Syntax error", &as->loc, word);
 
     return 1;
@@ -1232,10 +1283,7 @@ static uint8_t parse_indirect(As *as, char **c, uint8_t *r1, uint8_t *r2, uint16
             if (wlen == 0)
                 return error_l("Syntax error", &as->loc, "expected immediate");
 
-            if (!isdigit(*word))
-                return error_l("Syntax error", &as->loc, "expected immediate");
-
-            if (next_imm(word, imm))
+            if (!next_imm(as, word, imm))
                 return error_l("Syntax error", &as->loc, word);
 
             if (*imm > 0xff)
@@ -1301,14 +1349,10 @@ static uint8_t parse_jmp(As *as, char **c)
         return error_l("Syntax error", &as->loc, "expected label or immediate");
 
     /* JMP imm */
-    if (isdigit(*word))
-    {
-        if (next_imm(word, &imm))
-            return error_l("Syntax error", &as->loc, word);
-    }
-    /* JMP label */
-    else if (!new_ref(as, word, 0xffff, as->addr + 2))
-        return 0;
+    if (!next_imm(as, word, &imm))
+        /* JMP label */
+        if (!new_ref(as, word, 0xffff, as->addr + 2))
+            return 0;
 
     return (emit(as, 9, 0, FHH, FL) && emit_imm(as, imm));
 }
@@ -1339,14 +1383,10 @@ static uint8_t parse_call(As *as, char **c)
         return error_l("Syntax error", &as->loc, "expected label or immediate");
 
     /* CALL imm */
-    if (isdigit(*word))
-    {
-        if (next_imm(word, &imm))
-            return error_l("Syntax error", &as->loc, word);
-    }
-    /* CALL label */
-    else if (!new_ref(as, word, 0xffff, as->addr + 2))
-        return 0;
+    if (!next_imm(as, word, &imm))
+        /* CALL label */
+        if (!new_ref(as, word, 0xffff, as->addr + 2))
+            return 0;
 
     return (emit(as, 9, 0, FHH, 0) && emit_imm(as, imm));
 }
@@ -1433,11 +1473,8 @@ static uint8_t parse_ld(As *as, char **c)
         return emit(as, 1, r1, FHH, (r2 << 6));
 
     /* LD r1, imm */
-    if (isdigit(*word))
+    if (next_imm(as, word, &imm))
     {
-        if (next_imm(word, &imm))
-            return error_l("Syntax error", &as->loc, word);
-
         if (imm > 0xff)
             return error_l("Overflow in immediate", &as->loc, word);
     }