1 files changed, 137 insertions, 0 deletions
diff --git a/include/pushdown.h b/include/pushdown.h
new file mode 100644
index 0000000..aa7c308
--- /dev/null
+++ b/include/pushdown.h
@@ -0,0 +1,137 @@
+#ifndef PUSHDOWN_H
+#define PUSHDOWN_H
+
+typedef pushdown_value_t stack_value_t;
+#include "./stack.h"
+
+typedef enum {
+  END,
+  PUSH,
+  POP,
+  SKIP,
+  COPY,
+  ADD,
+  SUB,
+  MUL,
+  DIV,
+  SIN,
+  COS,
+  TAN,
+  ASIN,
+  ACOS,
+  ATAN,
+  SINH,
+  COSH,
+  TANH,
+  ASINH,
+  ACOSH,
+  ATANH,
+  EXP,
+  LOG,
+  SQRT,
+  ABS
+} pushdown_instruction_t;
+
+void pushdown_run(stack_t *, stack_t *, pushdown_instruction_t *);
+
+#endif
+
+#ifdef PUSHDOWN_IMPLEMENTATION
+
+#include <tgmath.h>
+
+void pushdown_run(stack_t *output, stack_t *input,
+                  pushdown_instruction_t *instructions) {
+  pushdown_instruction_t *op = instructions;
+
+  pushdown_value_t x, y;
+
+  while (*op) {
+    switch (*op) {
+    case PUSH:
+      stack_push(output, stack_pop(input));
+      break;
+    case POP:
+      stack_pop(output);
+      break;
+    case SKIP:
+      stack_pop(input);
+      break;
+    case COPY:
+      stack_push(output, stack_peek(output));
+      break;
+    case ADD:
+      x = stack_pop(output);
+      y = stack_pop(output);
+      stack_push(output, x + y);
+      break;
+    case SUB:
+      x = stack_pop(output);
+      y = stack_pop(output);
+      stack_push(output, x - y);
+      break;
+    case MUL:
+      x = stack_pop(output);
+      y = stack_pop(output);
+      stack_push(output, x * y);
+      break;
+    case DIV:
+      x = stack_pop(output);
+      y = stack_pop(output);
+      stack_push(output, x / y);
+      break;
+    case SIN:
+      stack_push(output, sin(stack_pop(output)));
+      break;
+    case COS:
+      stack_push(output, cos(stack_pop(output)));
+      break;
+    case TAN:
+      stack_push(output, tan(stack_pop(output)));
+      break;
+    case ASIN:
+      stack_push(output, asin(stack_pop(output)));
+      break;
+    case ACOS:
+      stack_push(output, acos(stack_pop(output)));
+      break;
+    case ATAN:
+      stack_push(output, atan(stack_pop(output)));
+      break;
+    case SINH:
+      stack_push(output, sinh(stack_pop(output)));
+      break;
+    case COSH:
+      stack_push(output, cosh(stack_pop(output)));
+      break;
+    case TANH:
+      stack_push(output, tanh(stack_pop(output)));
+      break;
+    case ASINH:
+      stack_push(output, asinh(stack_pop(output)));
+      break;
+    case ACOSH:
+      stack_push(output, acosh(stack_pop(output)));
+      break;
+    case ATANH:
+      stack_push(output, atanh(stack_pop(output)));
+      break;
+    case EXP:
+      stack_push(output, exp(stack_pop(output)));
+      break;
+    case LOG:
+      stack_push(output, log(stack_pop(output)));
+      break;
+    case SQRT:
+      stack_push(output, sqrt(stack_pop(output)));
+      break;
+    case ABS:
+      stack_push(output, fabs(stack_pop(output)));
+      break;
+    }
+
+    op++;
+  }
+}
+
+#endif
+\ No newline at end of file