# HG changeset patch
# User William Astle <lost@l-w.ca>
# Date 1572148915 21600
# Node ID 59b8c8b15bd4d0eaf189977ad2ac72e3dc36f867
# Parent  16bd8effb2f61b0451799cd4f9dff3654fffbc03
Add integer shifts and fix code template errors for mul/div/mod

One needs to remove stuff from the stack after putting it there. Actually do
that in the code output for multiplication, division, and modulus.

Add integer shifting code output which is optimized for constant shift
counts but calls a routine for non-constant shift counts. Shifting by a
negative amount is a no-op. Shifting by more than the size of an integer
results in 0 (for left shifts) or -1 (for right shifts). Both negative shift
counts and shift counts larger than the base type are undefined in the C
standard so this behaviour is allowed.

diff -r 16bd8effb2f6 -r 59b8c8b15bd4 lwcc/cc-gencode.c
--- a/lwcc/cc-gencode.c	Thu Oct 24 22:41:04 2019 -0600
+++ b/lwcc/cc-gencode.c	Sat Oct 26 22:01:55 2019 -0600
@@ -20,6 +20,7 @@
 */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include <lw_alloc.h>
@@ -36,6 +37,65 @@
     return lw_strdup(buf);
 }
 
+void generate_code(node_t *n, FILE *output);
+
+void generate_code_shift(node_t *n, FILE *output, int dir)
+{
+    generate_code(n -> children, output);
+    if (n -> children -> next_child -> type == NODE_CONST_INT)
+    {
+        long ival;
+        int i;
+        ival = strtol(n -> children -> next_child -> strval, NULL, 0);
+        if (ival <= 0)
+            return;
+        if (ival >= 16)
+        {
+            fprintf(output, "\tldd #%d\n", dir == 1 ? 0 : -1);
+            return;
+        }
+        if (ival >= 8)
+        {
+            if (dir == 1)
+            {
+                fprintf(output, "\ttfr b,a\n\tclrb\n");
+                for (i = ival - 8; i > 0; i--)
+                {
+                    fprintf(output, "\tlsla\n");
+                }
+            }
+            else
+            {
+                fprintf(output, "\ttfr a,b\n\tsex\n");
+                for (i = ival - 8; i > 0; i--)
+                {
+                    fprintf(output, "\tasrb\n");
+                }
+            }
+            return;
+        }
+        for (i = ival; i > 0; i--)
+        {
+            if (dir == 1)
+            {
+                fprintf(output, "\taslb\n\trola\n");
+            }
+            else
+            {
+                fprintf(output, "\tasra\n\trorb\n");
+            }
+        }
+        return;
+    }
+    else
+    {
+        fprintf(output, "\tpshs d\n");
+        generate_code(n -> children -> next_child, output);
+        fprintf(output, "\tjsr ___%ssh16\n\tpuls d\n", dir == 1 ? "l" : "r");
+    }
+}
+
+
 void generate_code(node_t *n, FILE *output)
 {
     node_t *nn;
@@ -45,7 +105,7 @@
     {
     // function definition - output prologue, then statements, then epilogue
     case NODE_FUNDEF:
-        fprintf(output, "_%s\n", n->children->next_child->strval);
+        fprintf(output, "\tsection .text\n\texport _%s\n_%s\n", n->children->next_child->strval, n->children->next_child->strval);
         generate_code(n->children->next_child->next_child->next_child, output);
         fprintf(output, "\trts\n");
         break;
@@ -72,21 +132,29 @@
         generate_code(n -> children, output);
         fprintf(output, "\tpshs d\n");
         generate_code(n->children->next_child, output);
-        fprintf(output, "\tjsr ___mul16i\n");
+        fprintf(output, "\tjsr ___mul16i\n\tpuls d\n");
         break;
 
     case NODE_OPER_DIVIDE:
         generate_code(n -> children, output);
         fprintf(output, "\tpshs d\n");
         generate_code(n->children->next_child, output);
-        fprintf(output, "\tjsr ___div16i\n");
+        fprintf(output, "\tjsr ___div16i\n\tpuls d\n");
         break;
     
     case NODE_OPER_MOD:
         generate_code(n -> children, output);
         fprintf(output, "\tpshs d\n");
         generate_code(n -> children -> next_child, output);
-        fprintf(output, "\tjsr ___mod16i\n");
+        fprintf(output, "\tjsr ___mod16i\n\tpuls d\n");
+        break;
+
+    case NODE_OPER_LSH:
+        generate_code_shift(n, output, 1);
+        break;
+
+    case NODE_OPER_RSH:
+        generate_code_shift(n, output, 0);
         break;
 
     case NODE_OPER_COND: