🐐 Compiler fixes

centvrion/compiler/emit_expr.py

@@ -129,7 +129,7 @@ def emit_expr(node, ctx):
   if isinstance(node, UnaryMinus):
     inner_lines, inner_var = emit_expr(node.expr, ctx)
     tmp = ctx.fresh_tmp()
-    return inner_lines + [f"CentValue {tmp} = cent_int(-{inner_var}.ival);"], tmp
+    return inner_lines + [f"CentValue {tmp} = cent_neg({inner_var});"], tmp
 
   if isinstance(node, UnaryNot):
     inner_lines, inner_var = emit_expr(node.expr, ctx)

centvrion/compiler/emitter.py

@@ -92,6 +92,8 @@ def compile_program(program):
   lines.append("  cent_init();")
   if "MAGNVM" in ctx.modules:
     lines.append("  cent_magnvm = 1;")
+  if "SVBNVLLA" in ctx.modules:
+    lines.append("  cent_svbnvlla = 1;")
   lines.append("  CentScope _scope = {0};")
   lines.append("  CentValue _return_val = cent_null();")
 

centvrion/compiler/runtime/cent_runtime.c

@@ -15,6 +15,7 @@
 
 CentArena *cent_arena;
 int cent_magnvm = 0;
+int cent_svbnvlla = 0;
 
 /* ------------------------------------------------------------------ */
 /* Portable xorshift32 RNG (matches Python _CentRng)                   */
@@ -181,7 +182,15 @@ void cent_int_to_roman(long n, char *buf, size_t bufsz) {
     if (bufsz > 6) { memcpy(buf, "NVLLVS", 6); buf[6] = '\0'; }
     return;
   }
-  if (n < 0 || (n > 3999 && !cent_magnvm))
+  if (n < 0) {
+    if (!cent_svbnvlla)
+      cent_runtime_error("number out of range for Roman numerals");
+    if (bufsz < 2) cent_runtime_error("Roman numeral buffer overflow");
+    buf[0] = '-';
+    cent_int_to_roman(-n, buf + 1, bufsz - 1);
+    return;
+  }
+  if (n > 3999 && !cent_magnvm)
     cent_runtime_error("number out of range for Roman numerals");
   size_t pos = 0;
   if (n > 3999) {
@@ -271,8 +280,13 @@ static int write_val(CentValue v, char *buf, int bufsz) {
     case CENT_FRAC: {
       long num = v.fval.num, den = v.fval.den;
       if (den < 0) { num = -num; den = -den; }
-      if (num < 0)
-        cent_runtime_error("cannot display negative numbers without SVBNVLLA");
+      int negative = 0;
+      if (num < 0) {
+        if (!cent_svbnvlla)
+          cent_runtime_error("cannot display negative numbers without SVBNVLLA");
+        negative = 1;
+        num = -num;
+      }
       long int_part = num / den;
       long rem_num  = num % den;
 
@@ -297,11 +311,13 @@ static int write_val(CentValue v, char *buf, int bufsz) {
         for (int i = 0; i < (int)((level_int % 6) % 2); i++) frac_buf[frac_pos++] = '.';
       }
 
-      n = int_len + frac_pos;
+      n = int_len + frac_pos + (negative ? 1 : 0);
       if (buf && n < bufsz) {
-        memcpy(buf, int_buf, int_len);
-        memcpy(buf + int_len, frac_buf, frac_pos);
-        buf[n] = '\0';
+        int pos = 0;
+        if (negative) buf[pos++] = '-';
+        memcpy(buf + pos, int_buf, int_len); pos += int_len;
+        memcpy(buf + pos, frac_buf, frac_pos); pos += frac_pos;
+        buf[pos] = '\0';
       }
       return n;
     }
@@ -391,6 +407,13 @@ static void to_frac(CentValue v, long *num, long *den) {
   else                     { *num = v.fval.num; *den = v.fval.den; }
 }
 
+CentValue cent_neg(CentValue v) {
+  if (v.type == CENT_INT)  return cent_int(-v.ival);
+  if (v.type == CENT_FRAC) return frac_reduce(-v.fval.num, v.fval.den);
+  cent_type_error("Unary minus requires a number");
+  return cent_null();
+}
+
 CentValue cent_add(CentValue a, CentValue b) {
   if (a.type == CENT_INT && b.type == CENT_INT)
     return cent_int(a.ival + b.ival);

centvrion/compiler/runtime/cent_runtime.h

@@ -97,6 +97,9 @@ extern CentArena *cent_arena;
 /* Set to 1 when CVM MAGNVM is active; enables extended numeral display */
 extern int cent_magnvm;
 
+/* Set to 1 when CVM SVBNVLLA is active; enables negative number display */
+extern int cent_svbnvlla;
+
 /* ------------------------------------------------------------------ */
 /* Value constructors                                                   */
 /* ------------------------------------------------------------------ */
@@ -197,6 +200,7 @@ char *cent_make_string(CentValue v);
 /* Arithmetic and comparison operators                                  */
 /* ------------------------------------------------------------------ */
 
+CentValue cent_neg(CentValue v);               /* unary minus: INT or FRAC */
 CentValue cent_add(CentValue a, CentValue b);  /* INT+INT or FRAC+FRAC/INT */
 CentValue cent_array_concat(CentValue a, CentValue b); /* @ operator: concatenate two arrays */
 CentValue cent_concat(CentValue a, CentValue b); /* & operator: coerce all types to str */