Add C rand24

CHANGELOG.md

@@ -6,6 +6,7 @@ All notable changes to this project will be documented in this file. See [Keep a
 
 ### Added
 
+- RND (`$`) now works in compiled programs, though backed by a different source of randomness.
 - GDT and GTM (`D` and `T`) now work in compiled programs.
 
 ## [1.6.2] - 2023-11-21

README.md

@@ -212,8 +212,6 @@ When using the `-c` flag, the input program will be translated into C code. The
 
 If the `-a` flag is additionally specified, the output program will use `getchar` and `putchar` for the `GTC` and `PTC` opcodes respectively. Otherwise, the output program will convert between UTF-8 and UTF-32 the same way the interpreter does.
 
-Compiled programs cannot use multiple threads, and at this time cannot use the `RND`, `GTM`, and `GDT` opcodes.
-
 ## Sample programs
 
 Here are some simple programs I've written.

src/compiler.cpp

@@ -14,6 +14,14 @@ void compiler::write_state(std::ostream& os) {
 
     os << header;
 
+    if (std::any_of(m_fragments->cbegin(), m_fragments->cend(), [](const auto& v) {
+            return std::any_of(v->begin(), v->end(), [](const auto& i) {
+                return i.m_op == instruction::operation::RND;
+            });
+        })) {
+        os << "srand(time(NULL));";
+    }
+
     for (size_t i = 0; i < m_fragments->size(); ++i) {
         const std::vector<instruction>& frag = *m_fragments->at(i);
         for (size_t j = 0; j < frag.size(); ++j) {
@@ -138,8 +146,8 @@ void compiler::get_c_code(const instruction& i, std::ostream& os, bool assume_as
             return;
         }
         case op::RND:
-            cerr << "Random number generation is not yet supported for compiled programs." << endl;
-            exit(EXIT_FAILURE);
+            os << "lws_push(stack, rand24());";
+            return;
         case op::GDT:
             os << "lws_push(stack, get_date());";
             return;

src/compiler/lightweight_stack.h

@@ -127,4 +127,36 @@ static inline int32_t get_date() {
     time_t t = time(NULL);
     return (int32_t)(t / SECS_PER_DAY);
 }
+
+static inline int32_t rand24() {
+#if RAND_MAX >= 0x00ffffff
+#if (RAND_MAX | (RAND_MAX >> 1)) == RAND_MAX
+    return (int32_t)(rand() << 8) >> 8;
+#else
+    // Unlikely, but not difficult
+    int x;
+    do {
+        x = rand();
+    } while (x > 0x00ffffff);
+    return (int32_t)(x << 8) >> 8;
+#endif
+#else
+    // RAND_MAX is [0x00007fff, 0x00ffffff)
+    // Uhh just use twelve bits from each call
+#if (RAND_MAX | (RAND_MAX >> 1)) == RAND_MAX
+    int lowTwelve = rand() & 0x0fff;
+    int highTwelve = rand() & 0x0fff;
+#else
+    // :(
+    int lowTwelve, highTwelve;
+    do {
+        lowTwelve = rand();
+    } while (lowTwelve > 0x0fff);
+    do {
+        highTwelve = rand();
+    } while (highTwelve > 0x0fff);
+#endif
+    return (((int32_t)highTwelve << 20) | ((int32_t)lowTwelve << 8)) >> 8;
+#endif
+}
 //)"