Port buffer cur/next pointers are Scheme values

* libguile/ports.h (scm_t_port_buffer): Change "cur" and "end" members
  to be SCM values, in preparation for changing port buffers to be
  Scheme vectors.
  (scm_get_byte_or_eof_unlocked, scm_peek_byte_or_eof_unlocked): Adapt.
* libguile/ports.c (scm_c_make_port_buffer): Initialize cur and end
  members.
  (looking_at_bytes): Use helper instead of incrementing cur.
  (scm_i_read_unlocked): Adapt to end type change.
  (CONSUME_PEEKED_BYTE): Use helper instead of incrementing cur.
  (scm_i_unget_bytes_unlocked): Use helper instead of comparing cur.
  (scm_i_write_unlocked): Fix for changing end/cur types.
* libguile/read.c (scm_i_scan_for_encoding): Use helpers instead of
  addressing cursors directly.
* libguile/rw.c (scm_write_string_partial): Likewise.
* libguile/ports-internal.h (scm_port_buffer_reset):
  (scm_port_buffer_reset_end, scm_port_buffer_can_take):
  (scm_port_buffer_can_put, scm_port_buffer_can_putback):
  (scm_port_buffer_did_take, scm_port_buffer_did_put):
  (scm_port_buffer_take_pointer, scm_port_buffer_put_pointer):
  (scm_port_buffer_putback): Adapt to data types.

1 files changed, 18 insertions, 11 deletions

diff --git a/libguile/ports-internal.h b/libguile/ports-internal.h
index 14d00c2a6..862d85800 100644
--- a/libguile/ports-internal.h
+++ b/libguile/ports-internal.h
@@ -36,51 +36,57 @@ scm_port_buffer_size (scm_t_port_buffer *buf)
 static inline void
 scm_port_buffer_reset (scm_t_port_buffer *buf)
 {
-  buf->cur = buf->end = 0;
+  buf->cur = buf->end = SCM_INUM0;
 }
 
 static inline void
 scm_port_buffer_reset_end (scm_t_port_buffer *buf)
 {
-  buf->cur = buf->end = scm_port_buffer_size (buf);
+  buf->cur = buf->end = scm_from_size_t (scm_port_buffer_size (buf));
 }
 
 static inline size_t
 scm_port_buffer_can_take (scm_t_port_buffer *buf)
 {
-  return buf->end - buf->cur;
+  return scm_to_size_t (buf->end) - scm_to_size_t (buf->cur);
 }
 
 static inline size_t
 scm_port_buffer_can_put (scm_t_port_buffer *buf)
 {
-  return scm_port_buffer_size (buf) - buf->end;
+  return scm_port_buffer_size (buf) - scm_to_size_t (buf->end);
+}
+
+static inline size_t
+scm_port_buffer_can_putback (scm_t_port_buffer *buf)
+{
+  return scm_to_size_t (buf->cur);
 }
 
 static inline void
 scm_port_buffer_did_take (scm_t_port_buffer *buf, size_t count)
 {
-  buf->cur += count;
+  buf->cur = scm_from_size_t (scm_to_size_t (buf->cur) + count);
 }
 
 static inline void
 scm_port_buffer_did_put (scm_t_port_buffer *buf, size_t count)
 {
-  buf->end += count;
+  buf->end = scm_from_size_t (scm_to_size_t (buf->end) + count);
 }
 
 static inline const scm_t_uint8 *
 scm_port_buffer_take_pointer (scm_t_port_buffer *buf)
 {
   signed char *ret = SCM_BYTEVECTOR_CONTENTS (buf->bytevector);
-  return ((scm_t_uint8 *) ret) + buf->cur;
+  return ((scm_t_uint8 *) ret) + scm_to_size_t (buf->cur);
 }
 
 static inline scm_t_uint8 *
 scm_port_buffer_put_pointer (scm_t_port_buffer *buf)
 {
   signed char *ret = SCM_BYTEVECTOR_CONTENTS (buf->bytevector);
-  return ((scm_t_uint8 *) ret) + buf->end;
+  return ((scm_t_uint8 *) ret) + scm_to_size_t (buf->end);
 }
 
 static inline size_t
@@ -108,12 +114,13 @@ static inline void
 scm_port_buffer_putback (scm_t_port_buffer *buf, const scm_t_uint8 *src,
                          size_t count)
 {
-  assert (count <= buf->cur);
+  assert (count <= scm_to_size_t (buf->cur));
 
   /* Sometimes used to move around data within a buffer, so we must use
      memmove.  */
-  buf->cur -= count;
-  memmove (SCM_BYTEVECTOR_CONTENTS (buf->bytevector) + buf->cur, src, count);
+  buf->cur = scm_from_size_t (scm_to_size_t (buf->cur) - count);
+  memmove (SCM_BYTEVECTOR_CONTENTS (buf->bytevector) + scm_to_size_t (buf->cur),
+           src, count);
 }
 
 enum scm_port_encoding_mode {