Add LISP interpreter

tool/plinko/lib/trace.h

@@ -0,0 +1,41 @@
+#ifndef COSMOPOLITAN_TOOL_PLINKO_LIB_TRACE_H_
+#define COSMOPOLITAN_TOOL_PLINKO_LIB_TRACE_H_
+#include "libc/str/str.h"
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+#define START_TRACE                    \
+  bool t;                              \
+  PairFn *pf;                          \
+  BindFn *bf;                          \
+  EvlisFn *ef;                         \
+  RecurseFn *rf;                       \
+  unsigned char mo;                    \
+  TailFn *tails[8];                    \
+  EvalFn *ev, *ex;                     \
+  memcpy(tails, kTail, sizeof(kTail)); \
+  ev = eval;                           \
+  bf = bind_;                          \
+  ef = evlis;                          \
+  ex = expand;                         \
+  pf = pairlis;                        \
+  rf = recurse;                        \
+  EnableTracing();                     \
+  t = trace;                           \
+  trace = true
+
+#define END_TRACE \
+  trace = t;      \
+  eval = ev;      \
+  bind_ = bf;     \
+  evlis = ef;     \
+  expand = ex;    \
+  pairlis = pf;   \
+  recurse = rf;   \
+  memcpy(kTail, tails, sizeof(kTail))
+
+void EnableTracing(void);
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_TOOL_PLINKO_LIB_TRACE_H_ */