Merge pull request #1 from RevCurtisP/select

Implemented SELECT, CASE, and DEFAULT statements

c02.c

@@ -54,10 +54,7 @@ void pword()
   getwrd();
   ACMNT(word);
   DEBUG("Parsing Word '%s'\n", word);
-  if (xstmnt[0])
+  if (xstmnt[0] && !wordis(xstmnt))
-    if (wordis(xstmnt))
-      xstmnt[0] = 0;
-    else
       ERROR("Expected '%s' statement\n", xstmnt, EXIT_FAILURE);
   if (!pmodfr() && !ptype(MTNONE))
     pstmnt();     //Parse Statement

c02.ppx

@@ -2,32 +2,7 @@
 <settings version="1.0">
 	<category name="expr.h" />
 	<category name="cond.h" />
-	<category name="asm.h" />
+	<category name="asm.h">
-	<category name="c02.c" />
-	<category name="stmnt.c">
-		<category name="Window">
-			<property name="Left" type="integer">-8</property>
-			<property name="Top" type="integer">-31</property>
-			<property name="Right" type="integer">952</property>
-			<property name="Bottom" type="integer">422</property>
-			<property name="Maximized" type="integer">1</property>
-			<property name="Active" type="integer">1</property>
-		</category>
-	</category>
-	<category name="asm.c" />
-	<category name="vars.c" />
-	<category name="parse.c">
-		<category name="Window">
-			<property name="Left" type="integer">52</property>
-			<property name="Top" type="integer">52</property>
-			<property name="Right" type="integer">760</property>
-			<property name="Bottom" type="integer">362</property>
-			<property name="Maximized" type="integer">0</property>
-			<property name="Active" type="integer">0</property>
-		</category>
-	</category>
-	<category name="include.c" />
-	<category name="expr.c">
 		<category name="Window">
 			<property name="Left" type="integer">78</property>
 			<property name="Top" type="integer">78</property>
@@ -37,7 +12,116 @@
 			<property name="Active" type="integer">0</property>
 		</category>
 	</category>
+	<category name="c02.c">
+		<category name="Window">
+			<property name="Left" type="integer">0</property>
+			<property name="Top" type="integer">0</property>
+			<property name="Right" type="integer">952</property>
+			<property name="Bottom" type="integer">310</property>
+			<property name="Maximized" type="integer">0</property>
+			<property name="Active" type="integer">0</property>
+		</category>
+	</category>
+	<category name="stmnt.c">
+		<category name="Window">
+			<property name="Left" type="integer">26</property>
+			<property name="Top" type="integer">26</property>
+			<property name="Right" type="integer">978</property>
+			<property name="Bottom" type="integer">336</property>
+			<property name="Maximized" type="integer">0</property>
+			<property name="Active" type="integer">0</property>
+		</category>
+	</category>
+	<category name="asm.c">
+		<category name="Window">
+			<property name="Left" type="integer">52</property>
+			<property name="Top" type="integer">52</property>
+			<property name="Right" type="integer">760</property>
+			<property name="Bottom" type="integer">362</property>
+			<property name="Maximized" type="integer">0</property>
+			<property name="Active" type="integer">0</property>
+		</category>
+	</category>
+	<category name="vars.c">
+		<category name="Window">
+			<property name="Left" type="integer">52</property>
+			<property name="Top" type="integer">52</property>
+			<property name="Right" type="integer">1004</property>
+			<property name="Bottom" type="integer">362</property>
+			<property name="Maximized" type="integer">0</property>
+			<property name="Active" type="integer">0</property>
+		</category>
+	</category>
+	<category name="parse.c">
+		<category name="Window">
+			<property name="Left" type="integer">78</property>
+			<property name="Top" type="integer">78</property>
+			<property name="Right" type="integer">1030</property>
+			<property name="Bottom" type="integer">388</property>
+			<property name="Maximized" type="integer">0</property>
+			<property name="Active" type="integer">0</property>
+		</category>
+	</category>
+	<category name="include.c">
+		<category name="Window">
+			<property name="Left" type="integer">104</property>
+			<property name="Top" type="integer">104</property>
+			<property name="Right" type="integer">1056</property>
+			<property name="Bottom" type="integer">414</property>
+			<property name="Maximized" type="integer">0</property>
+			<property name="Active" type="integer">0</property>
+		</category>
+	</category>
+	<category name="expr.c">
+		<category name="Window">
+			<property name="Left" type="integer">130</property>
+			<property name="Top" type="integer">130</property>
+			<property name="Right" type="integer">1082</property>
+			<property name="Bottom" type="integer">440</property>
+			<property name="Maximized" type="integer">0</property>
+			<property name="Active" type="integer">0</property>
+		</category>
+	</category>
 	<category name="parse.h" />
-	<category name="common.h" />
+	<category name="common.h">
+		<category name="Window">
+			<property name="Left" type="integer">-8</property>
+			<property name="Top" type="integer">-31</property>
+			<property name="Right" type="integer">952</property>
+			<property name="Bottom" type="integer">422</property>
+			<property name="Maximized" type="integer">1</property>
+			<property name="Active" type="integer">1</property>
+		</category>
+	</category>
 	<category name="files.c" />
+	<category name="common.c">
+		<category name="Window">
+			<property name="Left" type="integer">26</property>
+			<property name="Top" type="integer">26</property>
+			<property name="Right" type="integer">978</property>
+			<property name="Bottom" type="integer">336</property>
+			<property name="Maximized" type="integer">0</property>
+			<property name="Active" type="integer">0</property>
+		</category>
+	</category>
+	<category name="label.c">
+		<category name="Window">
+			<property name="Left" type="integer">104</property>
+			<property name="Top" type="integer">104</property>
+			<property name="Right" type="integer">812</property>
+			<property name="Bottom" type="integer">414</property>
+			<property name="Maximized" type="integer">0</property>
+			<property name="Active" type="integer">0</property>
+		</category>
+	</category>
+	<category name="cond.c">
+		<category name="Window">
+			<property name="Left" type="integer">130</property>
+			<property name="Top" type="integer">130</property>
+			<property name="Right" type="integer">838</property>
+			<property name="Bottom" type="integer">440</property>
+			<property name="Maximized" type="integer">0</property>
+			<property name="Active" type="integer">0</property>
+		</category>
+	</category>
 </settings>

doc/c02.txt

@@ -513,9 +513,48 @@ Note: In order to optimize the compiled code, the if and else statements
 are to 6502 relative branch instructions. This limits the amount of 
 generated code between the if statement and the end of the if/else block
 to slightly less than 127 characters. This should be sufficient in most
-cases, but larger code blocks can be accomodated using function calls or
+cases, but larger code blocks can be accommodated using function calls or
 goto statements.
 
+SELECT, CASE, AND DEFAULT STATEMENTS
+
+The select, case, an default statements are used to execute a specific
+block of code depending on the result of an expression.
+
+When using the select keyword, it is followed by an expression (surrounded
+by parenthesis) and an opening curly brace, which begins the select block.
+This must then be followed by a case statement.
+
+Each use of the case keyword is followed by term and a colon. If the 
+term is equal to select expression then the code immediately following 
+the is executed, otherwise, program execution transfers to the next 
+case or default statement. 
+
+The code between two case statements or a case and default statement is
+called a case block. At the end of a case block, program execution
+transfers to the end of the select block (the closing curly brace at
+the end of the default block).
+
+The last case block must be followed by a default statement. When using
+the default keyword, it is followed by a colon. The code between the
+default statement and the end of the select block (marked with a closing
+curly-brace) is called the default block and is executed if none of
+the case arguments matched the select expression.
+
+Example:
+  puts("You pressed ");
+  select (getc()) {
+    case $0D: putln("The Enter key");
+    case ' ': putln("The space bar");
+    case ltr: putln("The character in variable 'ltr'");
+    case s[2]: putln("The third character of string 's'"); 
+    default: putln("some other key");
+  }
+
+Note: It's possible for multiple case statement arguments to evaluate to
+the same value. In this case, only the first case block matching the
+select expression will be executed.
+
 WHILE LOOPS
 
 The while statement is used to conditionally execute code in a loop. When
@@ -532,7 +571,7 @@ Examples:
   while() if (rdkey()) break;                  //Wait for a keypress
 
 Note: While loops are compiled using the 6502 JMP statements, so the code
-blocks may be abritrarily large.
+blocks may be arbitrarily large.
 
 DO WHILE LOOPS
 

doc/c02vsC.txt

@@ -7,8 +7,8 @@ C02 only supports one data type: unsigned char.
 POINTERS
 
 C02 does not support pointer type variables or parameters. However, the
-address-of operator may be used in function calls.
+address-of operator may be used in function calls and the inline 
-
+statement.
 
 DECLARATIONS
 
@@ -28,3 +28,10 @@ EXPRESSIONS
 C02 supports the addition, subtraction, bitwise-and, bitwise-or, and 
 exclusive-or operators. The multiplication, division, and binary shift
 operators are not supported. These can be implemented through functions. 
+
+STATEMENTS
+
+Instead of the switch statement, C02 uses the select statement. The 
+select statement works almost identically to the switch statement except
+that case blocks do not fall through and the break statement does not
+exit a case block.

label.c

@@ -85,8 +85,6 @@ void reqlbl(char* lbname)
     
 }
 
-
-
 /* Pop Label from Stack and Emit on Next Line */
 int poplbl() 
 {
@@ -102,12 +100,27 @@ int poplbl()
   else if (lbtype == LTDWHL)
     strcpy(endlbl, lblnam[lblcnt]);
     //strcpy(cndlbl, lblnam[lblcnt]);
+  else if (lbtype == LTCASE)
+    strcpy(cndlbl, lblnam[lblcnt]);
   else
     setlbl(lblnam[lblcnt]);
-  inblck = lblblk[lblcnt-1];
+  if (lbtype != LTCASE)
+    inblck = lblblk[lblcnt-1];
   return lbtype;
 }
 
+/* Get Top Label and Return Type */
+int toplbl(char *rtlbl) 
+{
+  if (lblcnt) {
+    strcpy(rtlbl, lblnam[lblcnt-1]);
+    DEBUG("Found top label %s\n", rtlbl);
+    return lbltyp[lblcnt-1];
+  }
+  rtlbl[0] = 0; //Clear Label
+  return LTNONE;
+}
+
 /* Push Label onto Stack        *
  * Args: lbltyp - Label type    *
  * Uses: curlbl - Label to push */

label.h

@@ -18,7 +18,7 @@ int  lblcnt;                       //Number of Labels in stack
 int  lblnxt;                       //Sequence of next label to be generated
 char lbltmp[LABLEN+1];             //Label Temporary Storage
 
-enum ltypes {LTNONE, LTIF, LTLOOP, LTEND, LTDO, LTDWHL, LTFUNC}; //Label Types
+enum ltypes {LTNONE, LTIF, LTLOOP, LTEND, LTDO, LTDWHL, LTSLCT, LTCASE, LTFUNC}; //Label Types
 
 void prslbl();              //Parse Label From Code
 void newlbl(char* lbname);  //Generate New Block Label

stmnt.c

@@ -204,7 +204,7 @@ void pfor() {
 
 /* parse and compile if statement */
 void pif() {
-  DEBUG("Parsing IF statement '%c'\n", nxtchr);
+  DEBUG("Parsing IF statement\n", 0);
   expect('(');
   newlbl(cndlbl);      //Create New Label
   pshlbl(LTIF,cndlbl); //Push Onto Stack
@@ -214,7 +214,7 @@ void pif() {
 
 /* parse and compile else statement */
 void pelse() {
-  DEBUG("Parsing ELSE statement '%c'\n", nxtchr);
+  DEBUG("Parsing ELSE statement\n", 0);
   strcpy(lbltmp, lblasm);   //Save Line Label
   lblasm[0] = 0;            //and Clear It
   newlbl(skplbl);           //Create Skip Label
@@ -306,6 +306,47 @@ void pretrn() {
   lsrtrn = TRUE;  //Set RETURN flag
 }
 
+/* parse and compile select statement */
+void pslct() {
+  DEBUG("Parsing SELECT statement\n", 0);
+  expect('(');
+  prsxpr(')');            //Parse Expression
+  newlbl(endlbl);         //Create New Label
+  pshlbl(LTSLCT,endlbl);  //Push Onto Stack
+  bgnblk(TRUE);           //Check For and Begin Block
+  strcpy(xstmnt, "CASE"); //Require Next Statement to be CASE
+}
+
+/* process end of case block */
+void ecase() {
+  if (poplbl(cndlbl) != LTCASE)
+    ERROR("%s not at end of CASE block\n", word, EXIT_FAILURE);  
+  if (toplbl(endlbl) != LTSLCT)
+    ERROR("Illegal nesting in SELECT statement\n", 0, EXIT_FAILURE);  
+  asmlin("JMP", endlbl);  //Emit jump over default case
+  setlbl(cndlbl);  //Set entry point label to emit
+}
+
+/* parse and compile select statement */
+void pcase() {
+  if (strcmp(xstmnt, "CASE") == 0)
+    xstmnt[0] = 0;  //Clear xstmnt
+  else 
+	ecase("CASE");  //Process end of case block
+  prstrm();                //Parse CASE argument
+  asmlin("CMP", term);     //Emit Comparison
+  expect(':');
+  newlbl(cndlbl);          //Create Conditional Label
+  pshlbl(LTCASE, cndlbl);  //and Push onto Stack
+  asmlin("BNE", cndlbl);   //Emit skip of CASE body
+}
+
+/* parse and compile default statement */
+void pdflt() {
+  expect(':');
+  ecase(); //Process end of case block
+}
+
 /* parse and compile while statement */
 void pwhile() {
   DEBUG("Parsing WHILE statement '%c'\n", nxtchr);
@@ -385,15 +426,18 @@ void pstmnt()
     return;
   }
   if (wordis("SWITCH")) {
-    punimp();
+    ERROR("SWITCH not implemented. Use SELECT.\n", word, EXIT_FAILURE);  
-    return;  
+  }
+  if (wordis("SELECT")) {
+    pslct();
+    return;
   }
   if (wordis("CASE")) {
-    punimp();
+    pcase();
     return;  
   }
   if (wordis("DEFAULT")) {
-    punimp();
+    pdflt();
     return;  
   }
   if (wordis("WHILE")) {