Speed up port position access from Scheme

* libguile/ports-internal.h (scm_port_buffer_position):
  (scm_port_position_line, scm_port_position_set_line):
  (scm_port_position_column, scm_port_position_set_column): New
  helpers.
  (scm_t_port): Ports now hold position as a pair, so that Scheme can
  access it easily.
  (SCM_LINUM, SCM_COL, SCM_INCLINE, SCM_ZEROCOL, SCM_INCCOL)
  (SCM_DECCOL, SCM_TABCOL): Remove.
* libguile/ports.c (make_port_buffer): Rename from
  scm_c_make_port_buffer, make static, and take port as an argument so
  we can initialize the position field.
  (initialize_port_buffers): Adapt make_port_buffer change.
  (scm_c_make_port_with_encoding): Initialize position.
  (update_port_position): Rename from update_port_lf, and operate on
  port position objects.
  (scm_ungetc): Operate on port position objects.
  (scm_setvbuf, scm_expand_port_read_buffer_x): Adapt to
  make_port_buffer change.
  (scm_lfwrite): Adapt to call update_port_position.
  (scm_port_line, scm_set_port_line_x, scm_port_column)
  (scm_set_port_column_x): Adapt to use port positions.
* libguile/ports.h (scm_c_make_port_buffer): Remove internal decl.
* libguile/read.c: Adapt to use scm_port_line / scm_port_column instead
  of SCM_LINUM et al.
* module/ice-9/ports.scm (port-buffer-position, port-position-line)
  (port-position-column, set-port-position-line!)
  (set-port-position-column!): New accessors for the internals module.
* module/ice-9/sports.scm (advance-port-position!): Rename from
  port-advance-position! and use the new accessors.
  (read-char, port-fold-chars/iso-8859-1): Adapt to use
  advance-port-position!.

libguile/ports-internal.h

@@ -94,6 +94,7 @@ enum scm_port_buffer_field {
   SCM_PORT_BUFFER_FIELD_CUR,
   SCM_PORT_BUFFER_FIELD_END,
   SCM_PORT_BUFFER_FIELD_HAS_EOF_P,
+  SCM_PORT_BUFFER_FIELD_POSITION,
   SCM_PORT_BUFFER_FIELD_COUNT
 };
 
@@ -152,6 +153,39 @@ scm_port_buffer_set_has_eof_p (SCM buf, SCM has_eof_p)
                          has_eof_p);
 }
 
+/* The port position object is a pair that is referenced by the port.
+   To make things easier for Scheme port code, it is also referenced by
+   port buffers.  */
+static inline SCM
+scm_port_buffer_position (SCM buf)
+{
+  return SCM_SIMPLE_VECTOR_REF (buf, SCM_PORT_BUFFER_FIELD_POSITION);
+}
+
+static inline SCM
+scm_port_position_line (SCM position)
+{
+  return scm_car (position);
+}
+
+static inline void
+scm_port_position_set_line (SCM position, SCM line)
+{
+  scm_set_car_x (position, line);
+}
+
+static inline SCM
+scm_port_position_column (SCM position)
+{
+  return scm_cdr (position);
+}
+
+static inline void
+scm_port_position_set_column (SCM position, SCM column)
+{
+  scm_set_cdr_x (position, column);
+}
+
 static inline size_t
 scm_port_buffer_size (SCM buf)
 {
@@ -290,8 +324,7 @@ struct scm_t_port
 {
   /* Source location information.  */
   SCM file_name;
-  long line_number;
+  SCM position;
-  int column_number;
 
   /* Port buffers.  */
   SCM read_buf;
@@ -325,14 +358,6 @@ struct scm_t_port
 
 #define SCM_FILENAME(x)           (SCM_PORT (x)->file_name)
 #define SCM_SET_FILENAME(x, n)    (SCM_PORT (x)->file_name = (n))
-#define SCM_LINUM(x)              (SCM_PORT (x)->line_number)
-#define SCM_COL(x)                (SCM_PORT (x)->column_number)
-
-#define SCM_INCLINE(port)  	do {SCM_LINUM (port) += 1; SCM_COL (port) = 0;} while (0)
-#define SCM_ZEROCOL(port)  	do {SCM_COL (port) = 0;} while (0)
-#define SCM_INCCOL(port)  	do {SCM_COL (port) += 1;} while (0)
-#define SCM_DECCOL(port)  	do {if (SCM_COL (port) > 0) SCM_COL (port) -= 1;} while (0)
-#define SCM_TABCOL(port)  	do {SCM_COL (port) += 8 - SCM_COL (port) % 8;} while (0)
 
 SCM_INTERNAL scm_t_iconv_descriptors * scm_i_port_iconv_descriptors (SCM port);
 

libguile/ports.c

@@ -494,13 +494,15 @@ scm_i_dynwind_current_load_port (SCM port)
 
 /* Port buffers.  */
 
-SCM
+static SCM
-scm_c_make_port_buffer (size_t size)
+make_port_buffer (SCM port, size_t size)
 {
   SCM ret = scm_c_make_vector (SCM_PORT_BUFFER_FIELD_COUNT, SCM_INUM0);
 
   SCM_SIMPLE_VECTOR_SET (ret, SCM_PORT_BUFFER_FIELD_BYTEVECTOR,
                          scm_c_make_bytevector (size));
+  SCM_SIMPLE_VECTOR_SET (ret, SCM_PORT_BUFFER_FIELD_POSITION,
+                         SCM_PORT (port)->position);
   scm_port_buffer_set_has_eof_p (ret, SCM_BOOL_F);
 
   return ret;
@@ -649,8 +651,8 @@ initialize_port_buffers (SCM port)
     write_buf_size = 1;
 
   pt->read_buffering = read_buf_size;
-  pt->read_buf = scm_c_make_port_buffer (read_buf_size);
+  pt->read_buf = make_port_buffer (port, read_buf_size);
-  pt->write_buf = scm_c_make_port_buffer (write_buf_size);
+  pt->write_buf = make_port_buffer (port, write_buf_size);
 }
 
 SCM
@@ -672,6 +674,7 @@ scm_c_make_port_with_encoding (scm_t_port_type *ptob, unsigned long mode_bits,
   pt->conversion_strategy = conversion_strategy;
   pt->file_name = SCM_BOOL_F;
   pt->iconv_descriptors = NULL;
+  pt->position = scm_cons (SCM_INUM0, SCM_INUM0);
 
   pt->at_stream_start_for_bom_read  = 1;
   pt->at_stream_start_for_bom_write = 1;
@@ -1598,27 +1601,34 @@ scm_c_read (SCM port, void *buffer, size_t size)
 
 /* Update the line and column number of PORT after consumption of C.  */
 static inline void
-update_port_lf (scm_t_wchar c, SCM port)
+update_port_position (SCM port, scm_t_wchar c)
 {
+  SCM position = SCM_PORT (port)->position;
+  long line = scm_to_long (scm_port_position_line (position));
+  int column = scm_to_int (scm_port_position_column (position));
+
   switch (c)
     {
     case '\a':
     case EOF:
       break;
     case '\b':
-      SCM_DECCOL (port);
+      if (column > 0)
+        scm_port_position_set_column (position, scm_from_int (column - 1));
       break;
     case '\n':
-      SCM_INCLINE (port);
+      scm_port_position_set_line (position, scm_from_long (line + 1));
+      scm_port_position_set_column (position, SCM_INUM0);
       break;
     case '\r':
-      SCM_ZEROCOL (port);
+      scm_port_position_set_column (position, SCM_INUM0);
       break;
     case '\t':
-      SCM_TABCOL (port);
+      scm_port_position_set_column (position,
+                                    scm_from_int (column + 8 - column % 8));
       break;
     default:
-      SCM_INCCOL (port);
+      scm_port_position_set_column (position, scm_from_int (column + 1));
       break;
     }
 }
@@ -1898,7 +1908,7 @@ scm_getc (SCM port)
   scm_port_buffer_did_take (SCM_PORT (port)->read_buf, len);
   if (codepoint == EOF)
     scm_i_clear_pending_eof (port);
-  update_port_lf (codepoint, port);
+  update_port_position (port, codepoint);
 
   return codepoint;
 }
@@ -2031,9 +2041,18 @@ scm_ungetc (scm_t_wchar c, SCM port)
   if (SCM_UNLIKELY (result != result_buf))
     free (result);
 
+  {
+    long line;
+    int column;
+
+    line = scm_to_long (scm_port_position_line (pt->position));
+    column = scm_to_int (scm_port_position_column (pt->position));
+
     if (c == '\n')
-    SCM_LINUM (port) -= 1;
+      scm_port_position_set_line (pt->position, scm_from_long (line - 1));
-  SCM_DECCOL (port);
+    if (column > 0)
+      scm_port_position_set_column (pt->position, scm_from_int (column - 1));
+  }
 }
 #undef FUNC_NAME
 
@@ -2216,8 +2235,8 @@ SCM_DEFINE (scm_setvbuf, "setvbuf", 2, 1, 0,
 
   SCM_SET_CELL_WORD_0 (port, tag_word);
   pt->read_buffering = read_buf_size;
-  pt->read_buf = scm_c_make_port_buffer (read_buf_size);
+  pt->read_buf = make_port_buffer (port, read_buf_size);
-  pt->write_buf = scm_c_make_port_buffer (write_buf_size);
+  pt->write_buf = make_port_buffer (port, write_buf_size);
 
   if (saved_read_buf)
     scm_unget_bytes (scm_port_buffer_take_pointer (saved_read_buf),
@@ -2563,7 +2582,7 @@ SCM_DEFINE (scm_expand_port_read_buffer_x, "expand-port-read-buffer!", 2, 1, 0,
   if (SCM_UNBNDP (putback_p))
     putback_p = SCM_BOOL_F;
 
-  new_buf = scm_c_make_port_buffer (c_size);
+  new_buf = make_port_buffer (port, c_size);
   scm_port_buffer_set_has_eof_p (new_buf,
                                  scm_port_buffer_has_eof_p (pt->read_buf));
   if (scm_is_true (putback_p))
@@ -2780,7 +2799,7 @@ scm_c_write (SCM port, const void *ptr, size_t size)
 void
 scm_lfwrite (const char *ptr, size_t size, SCM port)
 {
-  int saved_line;
+  SCM position, saved_line;
 
   if (size == 0)
     return;
@@ -2789,12 +2808,14 @@ scm_lfwrite (const char *ptr, size_t size, SCM port)
 
   scm_c_write (port, ptr, size);
 
-  saved_line = SCM_LINUM (port);
+  position = SCM_PORT (port)->position;
+  saved_line = scm_port_position_line (position);
   for (; size; ptr++, size--)
-    update_port_lf ((scm_t_wchar) (unsigned char) *ptr, port);
+    update_port_position (port, (scm_t_wchar) (unsigned char) *ptr);
 
   /* Handle line buffering.  */
-  if ((SCM_CELL_WORD_0 (port) & SCM_BUFLINE) && saved_line != SCM_LINUM (port))
+  if ((SCM_CELL_WORD_0 (port) & SCM_BUFLINE) &&
+      !scm_is_eq (saved_line, scm_port_position_line (position)))
     scm_flush (port);
 }
 
@@ -3046,7 +3067,7 @@ SCM_DEFINE (scm_port_line, "port-line", 1, 0, 0,
 {
   port = SCM_COERCE_OUTPORT (port);
   SCM_VALIDATE_OPENPORT (1, port);
-  return scm_from_long (SCM_LINUM (port));
+  return scm_port_position_line (SCM_PORT (port)->position);
 }
 #undef FUNC_NAME
 
@@ -3058,7 +3079,8 @@ SCM_DEFINE (scm_set_port_line_x, "set-port-line!", 2, 0, 0,
 {
   port = SCM_COERCE_OUTPORT (port);
   SCM_VALIDATE_OPENPORT (1, port);
-  SCM_PORT (port)->line_number = scm_to_long (line);
+  scm_to_long (line);
+  scm_port_position_set_line (SCM_PORT (port)->position, line);
   return SCM_UNSPECIFIED;
 }
 #undef FUNC_NAME
@@ -3077,7 +3099,7 @@ SCM_DEFINE (scm_port_column, "port-column", 1, 0, 0,
 {
   port = SCM_COERCE_OUTPORT (port);
   SCM_VALIDATE_OPENPORT (1, port);
-  return scm_from_int (SCM_COL (port));
+  return scm_port_position_column (SCM_PORT (port)->position);
 }
 #undef FUNC_NAME
 
@@ -3089,7 +3111,8 @@ SCM_DEFINE (scm_set_port_column_x, "set-port-column!", 2, 0, 0,
 {
   port = SCM_COERCE_OUTPORT (port);
   SCM_VALIDATE_OPENPORT (1, port);
-  SCM_PORT (port)->column_number = scm_to_int (column);
+  scm_to_int (column);
+  scm_port_position_set_column (SCM_PORT (port)->position, column);
   return SCM_UNSPECIFIED;
 }
 #undef FUNC_NAME

libguile/ports.h

@@ -131,9 +131,6 @@ SCM_API void scm_dynwind_current_output_port (SCM port);
 SCM_API void scm_dynwind_current_error_port (SCM port);
 SCM_INTERNAL void scm_i_dynwind_current_load_port (SCM port);
 
-/* Port buffers.  */
-SCM_INTERNAL SCM scm_c_make_port_buffer (size_t size);
-
 /* Mode bits.  */
 SCM_INTERNAL long scm_i_mode_bits (SCM modes);
 SCM_API long scm_mode_bits (char *modes);

libguile/read.c

@@ -149,8 +149,8 @@ scm_i_input_error (char const *function,
   scm_simple_format (string_port,
 		     scm_from_locale_string ("~A:~S:~S: ~A"),
 		     scm_list_4 (fn,
-				 scm_from_long (SCM_LINUM (port) + 1),
+				 scm_sum (scm_port_line (port), SCM_INUM1),
-				 scm_from_int (SCM_COL (port) + 1),
+				 scm_sum (scm_port_column (port), SCM_INUM1),
 				 scm_from_locale_string (message)));
     
   string = scm_get_output_string (string_port);
@@ -434,8 +434,8 @@ scm_read_sexp (scm_t_wchar chr, SCM port, scm_t_read_opts *opts)
                                    : ')'));
 
   /* Need to capture line and column numbers here. */
-  long line = SCM_LINUM (port);
+  long line = scm_to_long (scm_port_line (port));
-  int column = SCM_COL (port) - 1;
+  int column = scm_to_int (scm_port_column (port)) - 1;
 
   c = flush_ws (port, opts, FUNC_NAME);
   if (terminating_char == c)
@@ -612,8 +612,8 @@ scm_read_string_like_syntax (int chr, SCM port, scm_t_read_opts *opts)
   scm_t_wchar c, c_str[READER_STRING_BUFFER_SIZE];
 
   /* Need to capture line and column numbers here. */
-  long line = SCM_LINUM (port);
+  long line = scm_to_long (scm_port_line (port));
-  int column = SCM_COL (port) - 1;
+  int column = scm_to_int (scm_port_column (port)) - 1;
 
   while (chr != (c = scm_getc (port)))
     {
@@ -739,8 +739,8 @@ scm_read_number (scm_t_wchar chr, SCM port, scm_t_read_opts *opts)
   size_t bytes_read;
 
   /* Need to capture line and column numbers here. */
-  long line = SCM_LINUM (port);
+  long line = scm_to_long (scm_port_line (port));
-  int column = SCM_COL (port) - 1;
+  int column = scm_to_int (scm_port_column (port)) - 1;
 
   scm_ungetc (chr, port);
   buffer = read_complete_token (port, opts, local_buffer, sizeof local_buffer,
@@ -759,7 +759,9 @@ scm_read_number (scm_t_wchar chr, SCM port, scm_t_read_opts *opts)
   else if (SCM_NIMP (result))
     result = maybe_annotate_source (result, port, opts, line, column);
 
-  SCM_COL (port) += scm_i_string_length (str);
+  scm_set_port_column_x (port,
+                         scm_sum (scm_port_column (port),
+                                  scm_string_length (str)));
   return result;
 }
 
@@ -796,7 +798,9 @@ scm_read_mixed_case_symbol (scm_t_wchar chr, SCM port, scm_t_read_opts *opts)
       result = scm_string_to_symbol (str);
     }
 
-  SCM_COL (port) += scm_i_string_length (str);
+  scm_set_port_column_x (port,
+                         scm_sum (scm_port_column (port),
+                                  scm_string_length (str)));
   return result;
 }
 
@@ -845,7 +849,9 @@ scm_read_number_and_radix (scm_t_wchar chr, SCM port, scm_t_read_opts *opts)
 
   result = scm_string_to_number (str, scm_from_uint (radix));
 
-  SCM_COL (port) += scm_i_string_length (str);
+  scm_set_port_column_x (port,
+                         scm_sum (scm_port_column (port),
+                                  scm_string_length (str)));
 
   if (scm_is_true (result))
     return result;
@@ -860,8 +866,8 @@ static SCM
 scm_read_quote (int chr, SCM port, scm_t_read_opts *opts)
 {
   SCM p;
-  long line = SCM_LINUM (port);
+  long line = scm_to_long (scm_port_line (port));
-  int column = SCM_COL (port) - 1;
+  int column = scm_to_int (scm_port_column (port)) - 1;
 
   switch (chr)
     {
@@ -907,8 +913,8 @@ static SCM
 scm_read_syntax (int chr, SCM port, scm_t_read_opts *opts)
 {
   SCM p;
-  long line = SCM_LINUM (port);
+  long line = scm_to_long (scm_port_line (port));
-  int column = SCM_COL (port) - 1;
+  int column = scm_to_int (scm_port_column (port)) - 1;
 
   switch (chr)
     {
@@ -1068,7 +1074,7 @@ scm_read_character (scm_t_wchar chr, SCM port, scm_t_read_opts *opts)
       ((unsigned char) buffer[0] <= 127
        || scm_is_eq (pt->encoding, sym_ISO_8859_1)))
     {
-      SCM_COL (port) += 1;
+      scm_set_port_column_x (port, scm_sum (scm_port_column (port), SCM_INUM1));
       return SCM_MAKE_CHAR (buffer[0]);
     }
 
@@ -1076,7 +1082,9 @@ scm_read_character (scm_t_wchar chr, SCM port, scm_t_read_opts *opts)
      processing.  */
   charname = scm_from_port_stringn (buffer, bytes_read, port);
   charname_len = scm_i_string_length (charname);
-  SCM_COL (port) += charname_len;
+  scm_set_port_column_x (port,
+                         scm_sum (scm_port_column (port),
+                                  scm_from_size_t (charname_len)));
   cp = scm_i_string_ref (charname, 0);
   if (charname_len == 1)
     return SCM_MAKE_CHAR (cp);
@@ -1629,8 +1637,8 @@ scm_read_sharp_extension (int chr, SCM port, scm_t_read_opts *opts)
   proc = scm_get_hash_procedure (chr);
   if (scm_is_true (scm_procedure_p (proc)))
     {
-      long line = SCM_LINUM (port);
+      long line = scm_to_long (scm_port_line (port));
-      int column = SCM_COL (port) - 2;
+      int column = scm_to_int (scm_port_column (port)) - 2;
       SCM got;
 
       got = scm_call_2 (proc, SCM_MAKE_CHAR (chr), port);
@@ -1782,8 +1790,8 @@ read_inner_expression (SCM port, scm_t_read_opts *opts)
                  be part of an unescaped symbol.  We might as well do
                  something useful with it, so we adopt Kawa's convention:
                  [...] => ($bracket-list$ ...) */
-              long line = SCM_LINUM (port);
+              long line = scm_to_long (scm_port_line (port));
-              int column = SCM_COL (port) - 1;
+              int column = scm_to_int (scm_port_column (port)) - 1;
               return maybe_annotate_source
                 (scm_cons (sym_bracket_list, scm_read_sexp (chr, port, opts)),
                  port, opts, line, column);
@@ -1805,8 +1813,8 @@ read_inner_expression (SCM port, scm_t_read_opts *opts)
 	  return (scm_read_quote (chr, port, opts));
 	case '#':
 	  {
-            long line  = SCM_LINUM (port);
+            long line = scm_to_long (scm_port_line (port));
-            int column = SCM_COL (port) - 1;
+            int column = scm_to_int (scm_port_column (port)) - 1;
 	    SCM result = scm_read_sharp (chr, port, opts, line, column);
 	    if (scm_is_eq (result, SCM_UNSPECIFIED))
 	      /* We read a comment or some such.  */
@@ -1870,8 +1878,8 @@ scm_read_expression (SCM port, scm_t_read_opts *opts)
           if (c == EOF)
             return SCM_EOF_VAL;
           scm_ungetc (c, port);
-          line = SCM_LINUM (port);
+          line = scm_to_long (scm_port_line (port));
-          column = SCM_COL (port);
+          column = scm_to_int (scm_port_column (port));
         }
 
       expr = read_inner_expression (port, opts);

module/ice-9/ports.scm

@@ -169,9 +169,14 @@ interpret its input and output."
             port-buffer-cur
             port-buffer-end
             port-buffer-has-eof?
+            port-buffer-position
             set-port-buffer-cur!
             set-port-buffer-end!
             set-port-buffer-has-eof?!
+            port-position-line
+            port-position-column
+            set-port-position-line!
+            set-port-position-column!
             port-read
             port-write
             port-clear-stream-start-for-bom-read
@@ -188,6 +193,7 @@ interpret its input and output."
 (define-syntax-rule (port-buffer-cur buf) (vector-ref buf 1))
 (define-syntax-rule (port-buffer-end buf) (vector-ref buf 2))
 (define-syntax-rule (port-buffer-has-eof? buf) (vector-ref buf 3))
+(define-syntax-rule (port-buffer-position buf) (vector-ref buf 4))
 
 (define-syntax-rule (set-port-buffer-cur! buf cur)
   (vector-set! buf 1 cur))
@@ -196,6 +202,15 @@ interpret its input and output."
 (define-syntax-rule (set-port-buffer-has-eof?! buf has-eof?)
   (vector-set! buf 3 has-eof?))
 
+(define-syntax-rule (port-position-line position)
+  (car position))
+(define-syntax-rule (port-position-column position)
+  (cdr position))
+(define-syntax-rule (set-port-position-line! position line)
+  (set-car! position line))
+(define-syntax-rule (set-port-position-column! position column)
+  (set-cdr! position column))
+
 (eval-when (expand)
   (define-syntax-rule (private-port-bindings binding ...)
     (begin

module/ice-9/sports.scm

@@ -384,34 +384,34 @@
   (peek-bytes port 1 fast-path
               (lambda (buf bv cur buffered) (slow-path))))
 
-(define-inlinable (port-advance-position! port char)
+(define-inlinable (advance-port-position! pos char)
   ;; FIXME: this cond is a speed hack; really we should just compile
   ;; `case' better.
   (cond
    ;; FIXME: char>? et al should compile well.
    ((<= (char->integer #\space) (char->integer char))
-    (set-port-column! port (1+ (port-column port))))
+    (set-port-position-column! pos (1+ (port-position-column pos))))
    (else
     (case char
       ((#\alarm) #t)                    ; No change.
       ((#\backspace)
-       (let ((col (port-column port)))
+       (let ((col (port-position-column pos)))
          (when (> col 0)
-           (set-port-column! port (1- col)))))
+           (set-port-position-column! pos (1- col)))))
       ((#\newline)
-       (set-port-line! port (1+ (port-line port)))
+       (set-port-position-line! pos (1+ (port-position-line pos)))
-       (set-port-column! port 0))
+       (set-port-position-column! pos 0))
       ((#\return)
-       (set-port-column! port 0))
+       (set-port-position-column! pos 0))
       ((#\tab)
-       (let ((col (port-column port)))
+       (let ((col (port-position-column pos)))
-         (set-port-column! port (- (+ col 8) (remainder col 8)))))
+         (set-port-position-column! pos (- (+ col 8) (remainder col 8)))))
       (else
-       (set-port-column! port (1+ (port-column port))))))))
+       (set-port-position-column! pos (1+ (port-position-column pos))))))))
 
 (define* (read-char #:optional (port (current-input-port)))
-  (define (finish char)
+  (define (finish buf char)
-    (port-advance-position! port char)
+    (advance-port-position! (port-buffer-position buf) char)
     char)
   (define (slow-path)
     (call-with-values (lambda () (peek-char-and-len port))
@@ -422,7 +422,7 @@
               (begin
                 (set-port-buffer-has-eof?! buf #f)
                 char)
-              (finish char))))))
+              (finish buf char))))))
   (define (fast-path buf bv cur buffered)
     (let ((u8 (bytevector-u8-ref bv cur))
           (enc (%port-encoding port)))
@@ -431,11 +431,11 @@
          (decode-utf8 bv cur buffered u8
                       (lambda (char len)
                         (set-port-buffer-cur! buf (+ cur len))
-                        (finish char))
+                        (finish buf char))
                       slow-path))
         ((ISO-8859-1)
          (set-port-buffer-cur! buf (+ cur 1))
-         (finish (integer->char u8)))
+         (finish buf (integer->char u8)))
         (else (slow-path)))))
   (peek-bytes port 1 fast-path
               (lambda (buf bv cur buffered) (slow-path))))
@@ -460,7 +460,7 @@
           (let ((ch (integer->char (bytevector-u8-ref bv cur)))
                 (cur (1+ cur)))
             (set-port-buffer-cur! buf cur)
-            (port-advance-position! port ch)
+            (advance-port-position! (port-buffer-position buf) ch)
             (call-with-values (lambda () (proc ch seed))
               (lambda (seed done?)
                 (if done? seed (fold-chars cur seed)))))))))))