From bc94bb205b91ab9f93879a7bd1339a641ffcbecd Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Fri, 25 Jan 2019 06:33:29 -0800
Subject: Provide faster bignum-in-fixed-integer range tests in MPI.

* mpi/mpi.c (mp_in_range, mp_in_intptr_range,
mp_in_uintptr_range): New functions.

* mpi/mpi.h (mp_in_range, mp_in_intptr_range,
mp_in_uintptr_range): Declared.

* arith.c (NUM_MAX_MP, INT_PTR_MAX_MP, UINT_PTR_MAX_MP,
INT_PTR_MAX_SUCC_MP): Static variables removed. Note that
INT_PTR_MAX_MP was not used at all!
(normalize): Use mp_in_range instead magnitude comparison to
NUM_MAX_MP.
(in_int_ptr_range, in_uint_ptr_range): Static functions removed.
(c_unum): Use mp_in_uintptr_range instead of
in_uint_ptr_range.
(arith_init): Remove initializations of removed variables.
(arith_free_all): Remove cleanup of removed variables, leaving
function empty.

* lib.c (c_num): Use mp_in_intptr_range instead of
in_int_ptr_range.
---
 arith.c   | 41 ++---------------------------------------
 lib.c     |  2 +-
 mpi/mpi.c | 31 +++++++++++++++++++++++++++++++
 mpi/mpi.h |  3 +++
 4 files changed, 37 insertions(+), 40 deletions(-)

diff --git a/arith.c b/arith.c
index 8bc459ca..f349b57a 100644
--- a/arith.c
+++ b/arith.c
@@ -54,9 +54,6 @@
 #define CNUM_BIT ((int) sizeof (cnum) * CHAR_BIT)
 #define ABS(A) ((A) < 0 ? -(A) : (A))
 
-static mp_int NUM_MAX_MP, INT_PTR_MAX_MP, UINT_PTR_MAX_MP;
-static mp_int INT_PTR_MAX_SUCC_MP;
-
 val make_bignum(void)
 {
   val n = make_obj();
@@ -165,7 +162,7 @@ val bignum_dbl_ipt(double_intptr_t di)
 
 val normalize(val bignum)
 {
-  if (mp_cmp_mag(mp(bignum), &NUM_MAX_MP) == MP_GT) {
+  if (!mp_in_range(mp(bignum), NUM_MAX, 0)) {
     return bignum;
   } else {
     cnum fixnum;
@@ -174,27 +171,6 @@ val normalize(val bignum)
   }
 }
 
-val in_int_ptr_range(val bignum)
-{
-  switch (mp_cmp_mag(mp(bignum), &INT_PTR_MAX_SUCC_MP)) {
-  default:
-  case MP_GT:
-    return nil;
-  case MP_EQ:
-    if (mp_cmp_z(mp(bignum)) == MP_GT)
-      return nil;
-    /* fallthrough */
-  case MP_LT:
-    return t;
-  }
-}
-
-static val in_uint_ptr_range(val bignum)
-{
-  return (mp_cmp_z(mp(bignum)) == MP_LT ||
-          mp_cmp_mag(mp(bignum), &UINT_PTR_MAX_MP) == MP_GT) ? nil : t;
-}
-
 ucnum c_unum(val num)
 {
   switch (type(num)) {
@@ -206,7 +182,7 @@ ucnum c_unum(val num)
     }
     goto range;
   case BGNUM:
-    if (in_uint_ptr_range(num)) {
+    if (mp_in_uintptr_range(mp(num))) {
       uint_ptr_t out;
       mp_get_uintptr(mp(num), &out);
       return out;
@@ -3348,15 +3324,6 @@ static val flo_set_round_mode(val mode)
 
 void arith_init(void)
 {
-  mp_init(&NUM_MAX_MP);
-  mp_set_intptr(&NUM_MAX_MP, NUM_MAX);
-  mp_init(&INT_PTR_MAX_MP);
-  mp_set_intptr(&INT_PTR_MAX_MP, INT_PTR_MAX);
-  mp_init(&UINT_PTR_MAX_MP);
-  mp_set_uintptr(&UINT_PTR_MAX_MP, -1);
-  mp_init(&INT_PTR_MAX_SUCC_MP);
-  mp_set_intptr(&INT_PTR_MAX_SUCC_MP, INT_PTR_MIN - 1);
-  mp_neg(&INT_PTR_MAX_SUCC_MP, &INT_PTR_MAX_SUCC_MP);
   log2_init();
 
   if (opt_compat && opt_compat <= 199) {
@@ -3423,8 +3390,4 @@ void arith_init(void)
 
 void arith_free_all(void)
 {
-  mp_clear(&NUM_MAX_MP);
-  mp_clear(&INT_PTR_MAX_MP);
-  mp_clear(&UINT_PTR_MAX_MP);
-  mp_clear(&INT_PTR_MAX_SUCC_MP);
 }
diff --git a/lib.c b/lib.c
index 26806b41..7e4edd9c 100644
--- a/lib.c
+++ b/lib.c
@@ -3105,7 +3105,7 @@ cnum c_num(val n)
   case CHR: case NUM:
     return coerce(cnum, n) >> TAG_SHIFT;
   case BGNUM:
-    if (in_int_ptr_range(n)) {
+    if (mp_in_intptr_range(mp(n))) {
       int_ptr_t out;
       mp_get_intptr(mp(n), &out);
       return out;
diff --git a/mpi/mpi.c b/mpi/mpi.c
index ff11f2e2..2097b574 100644
--- a/mpi/mpi.c
+++ b/mpi/mpi.c
@@ -469,6 +469,37 @@ mp_err mp_get_intptr(mp_int *mp, int_ptr_t *z)
   return MP_OKAY;
 }
 
+int mp_in_range(mp_int *mp, uint_ptr_t lim, int unsig)
+{
+  const int ptrnd = (SIZEOF_PTR + MP_DIGIT_BIT - 1) / MP_DIGIT_BIT;
+  mp_size nd = USED(mp);
+
+  if (unsig && ISNEG(mp))
+    return 0;
+
+  if (nd < ptrnd)
+    return 1;
+
+  if (nd > ptrnd)
+    return 0;
+
+  {
+    mp_digit top = DIGITS(mp)[ptrnd - 1];
+    lim >>= ((ptrnd - 1) * MP_DIGIT_BIT);
+    return top <= lim;
+  }
+}
+
+int mp_in_intptr_range(mp_int *mp)
+{
+  return mp_in_range(mp, INT_PTR_MAX, 0);
+}
+
+int mp_in_uintptr_range(mp_int *mp)
+{
+  return mp_in_range(mp, UINT_PTR_MAX, 1);
+}
+
 #ifdef HAVE_DOUBLE_INTPTR_T
 mp_err mp_set_double_intptr(mp_int *mp, double_intptr_t z)
 {
diff --git a/mpi/mpi.h b/mpi/mpi.h
index 28fadb31..71e08055 100644
--- a/mpi/mpi.h
+++ b/mpi/mpi.h
@@ -85,6 +85,9 @@ mp_err mp_set_uintptr(mp_int *mp, uint_ptr_t z);
 mp_err mp_set_intptr(mp_int *mp, int_ptr_t z);
 mp_err mp_get_uintptr(mp_int *mp, uint_ptr_t *z);
 mp_err mp_get_intptr(mp_int *mp, int_ptr_t *z);
+int mp_in_range(mp_int *mp, uint_ptr_t lim, int unsig);
+int mp_in_intptr_range(mp_int *mp);
+int mp_in_uintptr_range(mp_int *mp);
 #ifdef HAVE_DOUBLE_INTPTR_T
 mp_err mp_set_double_intptr(mp_int *mp, double_intptr_t z);
 #endif
-- 
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