match some of fraser/cuyler files.

rel/m_random_field/mRF_GetRandomStepMode.c

@@ -0,0 +1,5 @@
+#include "random_field.h"
+
+int mRF_GetRandomStepMode(void) {
+    return mRF_GetRandom(100) < 15;
+}

rel/m_random_field/mRF_MakePerfectBit.c

@@ -0,0 +1,10 @@
+#include "random_field.h"
+int mRF_MakePerfectBit(void) {
+    int perfect_bit = 0;
+    int i;
+    for (i = 0; i < mRF_PERFECT_BIT; i++) {
+        perfect_bit |= 1 << i;
+    }
+
+    return perfect_bit;
+}

rel/m_room_type/mRmTp_FtrItemNo2FtrIdx.c

@@ -0,0 +1,17 @@
+#include "roomtype.h"
+
+#define FTR_NO_2_FTR_IDX(f) ((f) >> 2)
+#define NUM_FTR_IN_TYPE (FTR_NO_2_FTR_IDX(0x1000))
+#define IS_FTR(f) ((f) == FG_FTR0_TYPE || (f) == FG_FTR1_TYPE)
+
+extern int mRmTp_FtrItemNo2FtrIdx(u16 ftr_no) {
+  int type = GET_FG_TYPE(ftr_no);
+  if (IS_FTR(type)) {
+    if (type == FG_FTR0_TYPE) {
+      return FTR_NO_2_FTR_IDX(ftr_no - FTR0_NO_START);
+    }
+    return FTR_NO_2_FTR_IDX(ftr_no - FTR1_NO_START) + NUM_FTR_IN_TYPE;
+  }
+
+  return NULL_NO;
+}