Merge pull request #465 from jimrees/master

changes from jim rees

bignum.c

@@ -67,6 +67,8 @@ sexp sexp_make_unsigned_integer (sexp ctx, sexp_luint_t x) {
 #define double_trunc_10s_digit(f) (trunc((f)/10.0)*10.0)
 #define double_10s_digit(f) ((f)-double_trunc_10s_digit(f))
 
+#define double_16s_digit(f) fmod(f,16.0)
+
 sexp sexp_double_to_bignum (sexp ctx, double f) {
   int sign;
   sexp_gc_var3(res, scale, tmp);
@@ -74,10 +76,10 @@ sexp sexp_double_to_bignum (sexp ctx, double f) {
   res = sexp_fixnum_to_bignum(ctx, SEXP_ZERO);
   scale = sexp_fixnum_to_bignum(ctx, SEXP_ONE);
   sign = (f < 0 ? -1 : 1);
-  for (f=fabs(f); f >= 1.0; f=trunc(f/10)) {
+  for (f=fabs(f); f >= 1.0; f=trunc(f/16)) {
-    tmp = sexp_bignum_fxmul(ctx, NULL, scale, (sexp_uint_t)double_10s_digit(f), 0);
+    tmp = sexp_bignum_fxmul(ctx, NULL, scale, (sexp_uint_t)double_16s_digit(f), 0);
     res = sexp_bignum_add(ctx, res, res, tmp);
-    scale = sexp_bignum_fxmul(ctx, NULL, scale, 10, 0);
+    scale = sexp_bignum_fxmul(ctx, NULL, scale, 16, 0);
   }
   sexp_bignum_sign(res) = sign;
   sexp_gc_release3(ctx);
@@ -730,6 +732,41 @@ sexp sexp_double_to_ratio (sexp ctx, double f) {
   return res;
 }
 
+//
+// For conversion that does not introduce round-off error,
+// no matter what FLT_RADIX is.
+//
+sexp sexp_double_to_ratio_2 (sexp ctx, double f) {
+  int sign,i;
+  sexp_gc_var3(res, whole, scale);
+  if (f == trunc(f))
+    return sexp_bignum_normalize(sexp_double_to_bignum(ctx, f));
+  sexp_gc_preserve3(ctx, res, whole, scale);
+  whole = sexp_double_to_bignum(ctx, trunc(f));
+  res = sexp_fixnum_to_bignum(ctx, SEXP_ZERO);
+  scale = SEXP_ONE;
+  sign = (f < 0 ? -1 : 1);
+  f = fabs(f-trunc(f));
+  while(f) {
+    res = sexp_bignum_fxmul(ctx, NULL, res, FLT_RADIX, 0);
+    scale = sexp_mul(ctx, scale, sexp_make_fixnum(FLT_RADIX));
+    f *= FLT_RADIX;
+    i = trunc(f);
+    if (i) {
+      f -= i;
+      res = sexp_bignum_fxadd(ctx, res, i);
+    }
+  }
+  sexp_bignum_sign(res) = sign;
+  res = sexp_bignum_normalize(res);
+  scale = sexp_bignum_normalize(scale);
+  res = sexp_make_ratio(ctx, res, scale);
+  res = sexp_ratio_normalize(ctx, res, SEXP_FALSE);
+  res = sexp_add(ctx, res, whole);
+  sexp_gc_release3(ctx);
+  return res;
+}
+
 sexp sexp_ratio_add (sexp ctx, sexp a, sexp b) {
   sexp_gc_var3(res, num, den);
   sexp_gc_preserve3(ctx, res, num, den);

eval.c

@@ -1817,7 +1817,7 @@ sexp sexp_inexact_to_exact (sexp ctx, sexp self, sexp_sint_t n, sexp z) {
       res = sexp_xtype_exception(ctx, self, "exact: not a finite number", z);
     } else if (sexp_flonum_value(z) != trunc(sexp_flonum_value(z))) {
 #if SEXP_USE_RATIOS
-      res = sexp_double_to_ratio(ctx, sexp_flonum_value(z));
+      res = sexp_double_to_ratio_2(ctx, sexp_flonum_value(z));
 #else
       res = sexp_xtype_exception(ctx, self, "exact: not an integer", z);
 #endif

include/chibi/bignum.h

@@ -44,6 +44,7 @@ SEXP_API sexp sexp_quotient (sexp ctx, sexp a, sexp b);
 SEXP_API sexp sexp_remainder (sexp ctx, sexp a, sexp b);
 #if SEXP_USE_RATIOS
 SEXP_API sexp sexp_double_to_ratio (sexp ctx, double f);
+SEXP_API sexp sexp_double_to_ratio_2 (sexp ctx, double f);
 SEXP_API double sexp_ratio_to_double (sexp rat);
 SEXP_API sexp sexp_make_ratio (sexp ctx, sexp num, sexp den);
 SEXP_API sexp sexp_ratio_normalize (sexp ctx, sexp rat, sexp in);

lib/chibi/show-test.sld

@@ -1,6 +1,7 @@
 (define-library (chibi show-test)
   (export run-tests)
-  (import (scheme base) (scheme char) (scheme read)
+  (import (scheme base) (scheme char) (scheme read) (scheme file)
+          (only (srfi 1) circular-list)
           (chibi test)
           (chibi show) (chibi show base) (chibi show color)
           (chibi show column) (chibi show pretty)
@@ -26,6 +27,9 @@
       (test "ABC" (show #f (upcased "abc")))
       (test "abc" (show #f (downcased "ABC")))
 
+      (test "a    b" (show #f "a" (space-to 5) "b"))
+      (test "ab" (show #f "a" (space-to 0) "b"))
+
       (test "abc     def" (show #f "abc" (tab-to) "def"))
       (test "abc  def" (show #f "abc" (tab-to 5) "def"))
       (test "abcdef" (show #f "abc" (tab-to 3) "def"))
@@ -33,6 +37,8 @@
       (test "abc\ndef\n" (show #f "abc" fl "def" nl fl))
       (test "abc\ndef\n" (show #f "abc" fl "def" fl fl))
 
+      (test "ab" (show #f "a" nothing "b"))
+
       ;; numbers
 
       (test "-1" (show #f -1))
@@ -142,6 +148,100 @@
       (test "100,000.00"
           (show #f (with ((comma-rule 3) (precision 2)) (numeric 100000))))
 
+      ;; radix argument:
+      (test "0" (show #f (numeric 0 2)))
+      (test "0" (show #f (numeric 0 10)))
+      (test "0" (show #f (numeric 0 36)))
+
+      (test "0.0" (show #f (numeric 0.0 2)))
+      (test "0.0" (show #f (numeric 0.0 10)))
+      (test "0.0" (show #f (numeric 0.0 36)))
+
+      (test "1" (show #f (numeric 1 2)))
+      (test "1" (show #f (numeric 1 10)))
+      (test "1" (show #f (numeric 1 36)))
+
+      (test "1.0" (show #f (numeric 1.0 2)))
+      (test "1.0" (show #f (numeric 1.0 10)))
+      (test "1.0" (show #f (numeric 1.0 36)))
+
+      (test "0" (show #f (numeric 0.0 10 0)))
+      (test "0" (show #f (numeric 0.0 9 0)))
+      (test "3/4" (show #f (numeric #e.75)))
+
+      (test "0.0000000000000001" (show #f (numeric 1e-25 36)))
+      (test "100000000000000000000000000000000000000000000000000000000000000000000000000000000.0"
+            (show #f (numeric (expt 2.0 80) 2)))
+
+      ;; numeric, radix=2
+      (test "10" (show #f (numeric 2 2)))
+      (test "10.0" (show #f (numeric 2.0 2)))
+      (test "11/10" (show #f (numeric 3/2 2)))
+      (test "1001" (show #f (numeric 9 2)))
+      (test "1001.0" (show #f (numeric 9.0 2)))
+      (test "1001.01" (show #f (numeric 9.25 2)))
+
+      ;; numeric, radix=3
+      (test "11" (show #f (numeric 4 3)))
+      (test "10.0" (show #f (numeric 3.0 3)))
+      (test "11/10" (show #f (numeric 4/3 3)))
+      (test "1001" (show #f (numeric 28 3)))
+      (test "1001.0" (show #f (numeric 28.0 3)))
+      (test "1001.01" (show #f (numeric #i253/9 3 2)))
+
+      ;; radix 36
+      (test "zzz" (show #f (numeric (- (* 36 36 36) 1) 36)))
+
+      ;; Precision:
+      (test "1.1250" (show #f (numeric 9/8 10 4)))
+      (test "1.125" (show #f (numeric 9/8 10 3)))
+      (test "1.12" (show #f (numeric 9/8 10 2)))
+      (test "1.1" (show #f (numeric 9/8 10 1)))
+      (test "1" (show #f (numeric 9/8 10 0)))
+
+      (test "1.1250" (show #f (numeric #i9/8 10 4)))
+      (test "1.125" (show #f (numeric #i9/8 10 3)))
+      (test "1.12" (show #f (numeric #i9/8 10 2)))
+      (test "1.1" (show #f (numeric #i9/8 10 1)))
+      (test "1" (show #f (numeric #i9/8 10 0)))
+
+      ;; precision-show, base-4
+      (test "1.1230" (show #f (numeric 91/64 4 4)))
+      (test "1.123" (show #f (numeric 91/64 4 3)))
+      (test "1.13" (show #f (numeric 91/64 4 2)))
+      (test "1.2" (show #f (numeric 91/64 4 1)))
+      (test "1" (show #f (numeric 91/64 4 0)))
+
+      (test "1.1230" (show #f (numeric #i91/64 4 4)))
+      (test "1.123" (show #f (numeric #i91/64 4 3)))
+      (test "1.13" (show #f (numeric #i91/64 4 2)))
+      (test "1.2" (show #f (numeric #i91/64 4 1)))
+      (test "1" (show #f (numeric #i91/64 4 0)))
+
+      ;; sign
+      (test "+1" (show #f (numeric 1 10 #f #t)))
+      (test "+1" (show #f (with ((sign-rule #t)) (numeric 1))))
+      (test "-0.0" (show #f (with ((sign-rule #t)) (numeric -0.0))))
+      (test "+0.0" (show #f (with ((sign-rule #t)) (numeric +0.0))))
+
+      ;; comma
+      (test "1,234,567" (show #f (numeric 1234567 10 #f #f 3)))
+      (test "567" (show #f (numeric 567 10 #f #f 3)))
+      (test "1,23,45,67" (show #f (numeric 1234567 10 #f #f 2)))
+
+      ;; comma-sep
+      (test "1|234|567" (show #f (numeric 1234567 10 #f #f 3 #\|)))
+      (test "1&234&567" (show #f (with ((comma-sep #\&)) (numeric 1234567 10 #f #f 3))))
+      (test "1*234*567" (show #f (with ((comma-sep #\&)) (numeric 1234567 10 #f #f 3 #\*))))
+      (test "567" (show #f (numeric 567 10 #f #f 3 #\|)))
+      (test "1,23,45,67" (show #f (numeric 1234567 10 #f #f 2)))
+
+      ;; decimal
+      (test "1_5" (show #f (with ((decimal-sep #\_)) (numeric 1.5))))
+      (test "1,5" (show #f (with ((comma-sep #\.)) (numeric 1.5))))
+      (test "1,5" (show #f (numeric 1.5 10 #f #f #f #\.)))
+      (test "1%5" (show #f (numeric 1.5 10 #f #f #f #\. #\%)))
+
       (cond-expand
        (complex
         (test "1+2i" (show #f (string->number "1+2i")))
@@ -151,6 +251,7 @@
             (show #f (with ((precision 2)) (string->number "3.14159+2i"))))))
 
       (test "608" (show #f (numeric/si 608)))
+      (test "608 B" (show #f (numeric/si 608 1000 " ") "B"))
       (test "3.9Ki" (show #f (numeric/si 3986)))
       (test "4kB" (show #f (numeric/si 3986 1000) "B"))
       (test "1.2Mm" (show #f (numeric/si 1.23e6 1000) "m"))
@@ -160,12 +261,14 @@
       (test "123m" (show #f (numeric/si 1.23e2 1000) "m"))
       (test "12.3m" (show #f (numeric/si 1.23e1 1000) "m"))
       (test "1.2m" (show #f (numeric/si 1.23 1000) "m"))
+      (test "1.2 m" (show #f (numeric/si 1.23 1000 " ") "m"))
       (test "123mm" (show #f (numeric/si 0.123 1000) "m"))
       (test "12.3mm" (show #f (numeric/si 1.23e-2 1000) "m")) ;?
       (test "1.2mm" (show #f (numeric/si 1.23e-3 1000) "m"))
       (test "123µm" (show #f (numeric/si 1.23e-4 1000) "m"))  ;?
       (test "12.3µm" (show #f (numeric/si 1.23e-5 1000) "m")) ;?
       (test "1.2µm" (show #f (numeric/si 1.23e-6 1000) "m"))
+      (test "1.2 µm" (show #f (numeric/si 1.23e-6 1000 " ") "m"))
 
       (test "1,234,567" (show #f (numeric/comma 1234567)))
 
@@ -177,7 +280,9 @@
 
       (test "abc  " (show #f (padded 5 "abc")))
       (test "  abc" (show #f (padded/left 5 "abc")))
+      (test "abcdefghi" (show #f (padded/left 5 "abcdefghi")))
       (test " abc " (show #f (padded/both 5 "abc")))
+      (test " abc  " (show #f (padded/both 6 "abc")))
       (test "abcde" (show #f (padded 5 "abcde")))
       (test "abcdef" (show #f (padded 5 "abcdef")))
 
@@ -204,6 +309,9 @@
       (test "abc :suffix" (show #f (trimmed/lazy 3 "abcde") " :suffix"))
       (test "abc :suffix" (show #f (trimmed/lazy 3 "abc\nde") " :suffix"))
 
+      (test "abc" (show #f (trimmed/lazy 10 (trimmed/lazy 3 "abcdefghijklmnopqrstuvwxyz"))))
+      (test "abc" (show #f (trimmed/lazy 3 (trimmed/lazy 10 "abcdefghijklmnopqrstuvwxyz"))))
+
       (test "abcde"
           (show #f (with ((ellipsis "...")) (trimmed 5 "abcde"))))
       (test "ab..."
@@ -286,9 +394,21 @@
 
       (test "hi, bob!" (show #f (escaped "hi, bob!")))
       (test "hi, \\\"bob!\\\"" (show #f (escaped "hi, \"bob!\"")))
+      (test "hi, \\'bob\\'" (show #f (escaped "hi, 'bob'" #\')))
+      (test "hi, ''bob''" (show #f (escaped "hi, 'bob'" #\' #\')))
+      (test "hi, ''bob''" (show #f (escaped "hi, 'bob'" #\' #f)))
+      (test "line1\\nline2\\nkapow\\a\\n"
+            (show #f (escaped "line1\nline2\nkapow\a\n"
+                              #\" #\\
+                              (lambda (c) (case c ((#\newline) #\n) ((#\alarm) #\a) (else #f))))))
+
       (test "bob" (show #f (maybe-escaped "bob" char-whitespace?)))
       (test "\"hi, bob!\""
-          (show #f (maybe-escaped "hi, bob!" char-whitespace?)))
+            (show #f (maybe-escaped "hi, bob!" char-whitespace?)))
+      (test "\"foo\\\"bar\\\"baz\"" (show #f (maybe-escaped "foo\"bar\"baz" char-whitespace?)))
+      (test "'hi, ''bob'''" (show #f (maybe-escaped "hi, 'bob'" (lambda (c) #f) #\' #f)))
+      (test "\\" (show #f (maybe-escaped "\\" (lambda (c) #f) #\' #f)))
+      (test "''''" (show #f (maybe-escaped "'" (lambda (c) #f) #\' #f)))
 
       ;; shared structures
 
@@ -426,6 +546,18 @@
                               (ones ',ones))
                           (append zeros ones))))))
 
+      ;; pretty-simply
+      (let* ((d (let ((d (list 'a 'b #f)))
+                  (list-set! d 2 d)
+                  (list d)))
+             (ca (circular-list 'a)))
+        (test "((a b (a b (a b" (show #f (trimmed/lazy 15 (pretty-simply '((a b (a b (a b (a b)))))))))
+        (test "((a b\n    (a b\n" (show #f (trimmed/lazy 15 (pretty-simply d))))
+        (test "'(a a\n    a\n   " (show #f (trimmed/lazy 15 (pretty-simply `(quote ,ca)))))
+        (test "(foo\n (a a\n    " (show #f (trimmed/lazy 15 (pretty-simply `(foo ,ca)))))
+        (test "(with-x \n  (a a" (show #f (trimmed/lazy 15 (pretty-simply `(with-x ,ca)))))
+        )
+
       ;; columns
 
       (test "abc\ndef\n"
@@ -594,6 +726,18 @@ def | 6
       (test "〜日本語〜"
           (show #f (with ((pad-char #\〜)) (padded/both 5 "日本語"))))
       (test "日本語"
-          (show #f (as-unicode (with ((pad-char #\〜)) (padded/both 5 "日本語")))))
+            (show #f (as-unicode (with ((pad-char #\〜)) (padded/both 5 "日本語")))))
+
+      ;; from-file
+      ;; for reference, filesystem-test relies on creating files under /tmp
+      (let* ((tmp-file "/tmp/chibi-show-test-0123456789")
+             (content-string "first line\nsecond line\nthird line"))
+        (with-output-to-file tmp-file (lambda () (write-string content-string)))
+        (test (string-append content-string "\n")
+              (show #f (from-file tmp-file)))
+        (test
+         "   1 first line\n   2 second line\n   3 third line\n"
+         (show #f (columnar 4 'right 'infinite (line-numbers) " " (from-file tmp-file))))
+        (delete-file tmp-file))
 
       (test-end))))

lib/chibi/show/column.scm

@@ -464,15 +464,15 @@
             cons))
           "\n"))))))
 
-(define (from-file path)
+(define (from-file path . ls)
-  (fn ()
+  (let-optionals* ls ((sep nl))
-    (call-with-input-file path
+    (fn ()
-      (lambda (in)
+      (let ((in (open-input-file path)))
         (let lp ()
           (let ((line (read-line in)))
             (if (eof-object? line)
-                nothing
+                (begin (close-input-port in) nothing)
-                (each line
+                (each line sep
                       (fn () (lp))))))))))
 
 (define (line-numbers . o)

lib/chibi/show/pretty.scm

@@ -63,7 +63,7 @@
                         ((> col width)
                          (abort fail))
                         (else
-                         (output str)))))))))
+                         (output-default str)))))))))
          (fn-fork
           (with ((output output*)
                  (port out))
@@ -151,7 +151,7 @@
            => cdr)
           (else #f))))
     (if (and (number? indent) (negative? indent))
-        (max 0 (- (+ (length+ form) indent) 1))
+        (max 0 (- (+ (or (length+ form) +inf.0) indent) 1))
         indent)))
 
 (define (with-reset-shares shares proc)
@@ -182,9 +182,11 @@
              ;; reset in case we don't fit on the first line
              (reset-shares (with-reset-shares shares nothing)))
          (call-with-output
-          (each " "
+          (trimmed/lazy (- width col2)
-                (joined/shares
+                        (each " "
-                 (lambda (x) (pp-flat x pp shares)) fixed shares " "))
+                              (joined/shares
+                               (lambda (x) (pp-flat x pp shares)) fixed shares " "))
+                        )
           (lambda (first-line)
             (cond
              ((< (+ col2 (string-width first-line)) width)
@@ -195,7 +197,7 @@
                       (cond
                        ((not (or (null? tail) (pair? tail)))
                         (each ". " (pp tail pp shares)))
-                       ((> (length+ (cdr ls)) (or indent-rule 1))
+                       ((> (or (length+ (cdr ls)) +inf.0) (or indent-rule 1))
                         (each sep (joined/shares pp tail shares sep)))
                        (else
                         nothing)))))
@@ -299,7 +301,7 @@
   (cond
    ;; one element list, no lines to break
    ((null? (cdr ls))
-    (each "(" (pretty (car ls)) ")"))
+    (each "(" (pp (car ls)) ")"))
    ;; quote or other abbrev
    ((and (pair? (cdr ls)) (null? (cddr ls))
          (assq (car ls) syntax-abbrevs))
@@ -362,7 +364,5 @@
 
 (define (pretty-simply obj)
   (fn ()
-    (call-with-output
+    (each (pp obj (extract-shared-objects #f #f))
-     (each (pp obj (extract-shared-objects #f #f))
+          fl)))
-           fl)
-     displayed)))

lib/chibi/show/show.scm

@@ -115,7 +115,7 @@
                     (right (if (even? diff)
                                left
                                (make-string (+ 1 diff/2) pad-char))))
-               (each right str left))
+               (each left str right))
              (displayed str)))))))
 
 ;;> As \scheme{padded/both} but only applies padding on the right.
@@ -136,7 +136,7 @@
    (lambda (str)
      (fn (string-width pad-char)
        (let ((diff (- width (string-width str))))
-         (each (make-string diff pad-char) str))))))
+         (each (make-string (max 0 diff) pad-char) str))))))
 
 ;; General buffered trim - capture the output apply a trimmer.
 (define (trimmed/buffered width producer proc)
@@ -211,7 +211,7 @@
 ;;> (e.g. \scheme{write-simple} on an infinite list).  The nature of
 ;;> this procedure means only truncating on the right is meaningful.
 (define (trimmed/lazy width . ls)
-  (fn (orig-output string-width)
+  (fn ((orig-output output) string-width)
     (call-with-current-continuation
      (lambda (return)
        (let ((chars-written 0)

lib/chibi/show/write.scm

@@ -41,8 +41,9 @@
   (let-optionals* o ((quot #\")
                      (esc #\\)
                      (rename (lambda (x) #f)))
-    (let ((quot-str (if (char? quot) (string quot) quot))
+    (let ((esc-str (cond ((char? esc) (string esc))
-          (esc-str (if (char? esc) (string esc) esc)))
+                         ((not esc) (string quot))
+                         (else esc))))
       (fn (output)
         (define (output* str)
           (let ((start (string-cursor-start str))
@@ -97,7 +98,10 @@
 (define (integer-log a base)
   (if (zero? a)
       0
-      (exact (ceiling (/ (log (+ a 1)) (log base))))))
+      ;; (exact (ceiling (/ (log (+ a 1)) (log base))))
+      (do ((ndigits 1 (+ ndigits 1))
+           (p base (* p base)))
+          ((> p a) ndigits))))
 
 ;; The original fmt algorithm was based on "Printing Floating-Point
 ;; Numbers Quickly and Accurately" by Burger and Dybvig
@@ -116,13 +120,13 @@
                      (comma unspec) (commasep unspec) (decsep unspec))
     (fn (radix precision sign-rule
                comma-rule comma-sep decimal-sep decimal-align)
-      (let ((radix (default rad radix))
+      (let* ((radix (default rad radix))
-            (precision (default prec precision))
+             (precision (default prec precision))
-            (sign-rule (default sgn sign-rule))
+             (sign-rule (default sgn sign-rule))
-            (comma-rule (default comma comma-rule))
+             (comma-rule (default comma comma-rule))
-            (comma-sep (default comma-sep commasep))
+             (comma-sep (default commasep comma-sep))
-            (dec-sep (default decsep
+             (dec-sep (default decsep
-                       (or decimal-sep (if (eqv? comma-sep #\.) #\, #\.)))))
+                        (or decimal-sep (if (eqv? comma-sep #\.) #\, #\.)))))
         ;; General formatting utilities.
         (define (get-scale q)
           (expt radix (- (integer-log q radix) 1)))
@@ -155,23 +159,26 @@
                            (and prev (odd? prev)))))
                 (round-up ls)
                 ls)))
-        (define (maybe-trim-zeros i res)
+        (define (maybe-trim-zeros i res inexact?)
           (if (and (not precision) (positive? i))
               (let lp ((res res))
                 (cond
                  ((and (pair? res) (eqv? 0 (car res))) (lp (cdr res)))
-                 ((and (pair? res) (eqv? dec-sep (car res))) (cdr res))
+                 ((and (pair? res) (eqv? dec-sep (car res)))
+                  (if inexact?
+                      (cons 0 res)      ; "1.0"
+                      (cdr res)))       ; "1"
                  (else res)))
               res))
         ;; General slow loop to generate digits one at a time, for
         ;; non-standard radixes or writing rationals with a fixed
         ;; precision.
-        (define (gen-general n)
+        (define (gen-general n-orig)
-          (let* ((p (exact n))
+          (let* ((p (exact n-orig))
                  (n (numerator p))
                  (d (denominator p)))
             (let lp ((n n)
-                     (i (- (integer-log p radix)))
+                     (i (if (zero? p) -1 (- (integer-log p radix))))
                      (res '()))
               (cond
                ;; Use a fixed precision if specified, otherwise generate
@@ -182,8 +189,8 @@
                                res))
                       (q (quotient n d)))
                   (cond
-                   ((>= q radix)
+                   ((< i -1)
-                    (let* ((scale (get-scale q))
+                    (let* ((scale (expt radix (- -1 i)))
                            (digit (quotient q scale))
                            (n2 (- n (* d digit scale))))
                       (lp n2 (+ i 1) (cons digit res))))
@@ -194,7 +201,7 @@
                (else
                 (list->string
                  (map char-digit
-                      (reverse (maybe-round n d (maybe-trim-zeros i res))))))))))
+                      (reverse (maybe-trim-zeros i (maybe-round n d res) (inexact? n-orig))))))))))
         ;; Generate a fixed precision decimal result by post-editing the
         ;; result of string->number.
         (define (gen-fixed n)
@@ -242,11 +249,11 @@
            (precision
             (gen-fixed n))
            ((and (exact? n) (not (integer? n)))
-            (string-append (number->string (numerator n) radix)
+            (string-append (gen-positive-real (numerator n))
                            "/"
-                           (number->string (denominator n) radix)))
+                           (gen-positive-real (denominator n))))
            ((memv radix (if (exact? n) '(2 8 10 16) '(10)))
-            (number->string n))
+            (number->string n radix))
            (else
             (gen-general n))))
         ;; Insert commas according to the current comma-rule.
@@ -272,14 +279,26 @@
             (if comma-rule (insert-commas s1) s1)))
         ;; Wrap the sign of a real number, forcing a + prefix or using
         ;; parentheses (n) for negatives according to sign-rule.
+
+        (define-syntax is-neg-zero?
+          (syntax-rules ()
+            ((_ n)
+             (is-neg-zero? (-0.0) n))
+            ((_ (0.0) n)                ; -0.0 is not distinguished?
+             #f)
+            ((_ (-0.0) n)
+             (eqv? -0.0 n))))
+        (define (negative?* n)
+          (or (negative? n)
+              (is-neg-zero? n)))
         (define (wrap-sign n sign-rule)
           (cond
-           ((negative? n)
+           ((negative?* n)
             (if (char? sign-rule)
                 (string-append (string sign-rule)
-                               (wrap-comma (abs n))
+                               (wrap-comma (- n))
                                (string (char-mirror sign-rule)))
-                (string-append "-" (wrap-comma (abs n)))))
+                (string-append "-" (wrap-comma (- n)))))
            ((eq? #t sign-rule)
             (string-append "+" (wrap-comma n)))
            (else
@@ -335,7 +354,8 @@
           (each (if (integer? n2)
                     (number->string (exact n2))
                     (inexact n2))
-                (if (zero? k) "" separator)
+                ;; (if (zero? k) "" separator)
+                separator
                 (vector-ref names k)))))))
 
 ;; Force a number into a fixed width, print as #'s if doesn't fit.