diff --git a/boards/arm/sam34/sam4l-xplained/src/sam_slcd.c b/boards/arm/sam34/sam4l-xplained/src/sam_slcd.c
index 59e3d99182..78a8037ed1 100644
--- a/boards/arm/sam34/sam4l-xplained/src/sam_slcd.c
+++ b/boards/arm/sam34/sam4l-xplained/src/sam_slcd.c
@@ -226,15 +226,6 @@
  * Private Type Definition
  ****************************************************************************/
 
-/* SLCD incoming stream structure */
-
-struct slcd_instream_s
-{
-  struct lib_instream_s stream;
-  const char *buffer;
-  ssize_t nbytes;
-};
-
 /* Global SLCD state */
 
 struct sam_slcdstate_s
@@ -514,30 +505,6 @@ static inline void slcd_clrdp(uint8_t curpos)
   slcd_clrpixel(&g_binfo[curpos + 3]);
 }
 
-/****************************************************************************
- * Name: slcd_getstream
- *
- * Description:
- *   Get one character from the keyboard.
- *
- ****************************************************************************/
-
-static int slcd_getstream(struct lib_instream_s *instream)
-{
-  struct slcd_instream_s *slcdstream =
-                                 (struct slcd_instream_s *)instream;
-
-  DEBUGASSERT(slcdstream && slcdstream->buffer);
-  if (slcdstream->nbytes > 0)
-    {
-      slcdstream->nbytes--;
-      slcdstream->stream.nget++;
-      return (int)*slcdstream->buffer++;
-    }
-
-  return EOF;
-}
-
 /****************************************************************************
  * Name: slcd_getcontrast
  ****************************************************************************/
@@ -899,7 +866,7 @@ static ssize_t slcd_read(struct file *filep,
 static ssize_t slcd_write(struct file *filep,
                           const char *buffer, size_t len)
 {
-  struct slcd_instream_s instream;
+  struct lib_meminstream_s instream;
   struct slcdstate_s state;
   enum slcdret_e result;
   uint8_t ch;
@@ -908,10 +875,7 @@ static ssize_t slcd_write(struct file *filep,
 
   /* Initialize the stream for use with the SLCD CODEC */
 
-  instream.stream.getc = slcd_getstream;
-  instream.stream.nget = 0;
-  instream.buffer      = buffer;
-  instream.nbytes      = len;
+  lib_meminstream(&instream, buffer, len);
 
   /* Initialize the SLCD decode state buffer */
 
@@ -920,8 +884,8 @@ static ssize_t slcd_write(struct file *filep,
   /* Decode and process every byte in the input buffer */
 
   options = 0;
-  while ((result = slcd_decode(&instream.stream, &state, &ch, &count)) !=
-          SLCDRET_EOF)
+  while ((result = slcd_decode(&instream.public,
+                               &state, &ch, &count)) != SLCDRET_EOF)
     {
       lcdinfo("slcd_decode returned result=%d char=%d count=%d\n",
               result, ch, count);
diff --git a/boards/arm/stm32/stm32ldiscovery/src/stm32_lcd.c b/boards/arm/stm32/stm32ldiscovery/src/stm32_lcd.c
index 4832ca4ad1..cebd5eeda7 100644
--- a/boards/arm/stm32/stm32ldiscovery/src/stm32_lcd.c
+++ b/boards/arm/stm32/stm32ldiscovery/src/stm32_lcd.c
@@ -285,15 +285,6 @@
  * Private Type Definition
  ****************************************************************************/
 
-/* SLCD incoming stream structure */
-
-struct slcd_instream_s
-{
-  struct lib_instream_s stream;
-  const char *buffer;
-  ssize_t nbytes;
-};
-
 /* Global SLCD state */
 
 struct stm32_slcdstate_s
@@ -530,30 +521,6 @@ static void slcd_clear(void)
   putreg32(1, SLCD_SR_UDR_BB);
 }
 
-/****************************************************************************
- * Name: slcd_getstream
- *
- * Description:
- *   Get one character from the keyboard.
- *
- ****************************************************************************/
-
-static int slcd_getstream(struct lib_instream_s *instream)
-{
-  struct slcd_instream_s *slcdstream = (struct slcd_instream_s *)
-                                           instream;
-
-  DEBUGASSERT(slcdstream && slcdstream->buffer);
-  if (slcdstream->nbytes > 0)
-    {
-      slcdstream->nbytes--;
-      slcdstream->stream.nget++;
-      return (int)*slcdstream->buffer++;
-    }
-
-  return EOF;
-}
-
 /****************************************************************************
  * Name: slcd_getcontrast
  ****************************************************************************/
@@ -1165,7 +1132,7 @@ static ssize_t slcd_read(struct file *filep, char *buffer,
 static ssize_t slcd_write(struct file *filep,
                           const char *buffer, size_t len)
 {
-  struct slcd_instream_s instream;
+  struct lib_meminstream_s instream;
   struct slcdstate_s state;
   enum slcdret_e result;
   uint8_t ch;
@@ -1175,17 +1142,14 @@ static ssize_t slcd_write(struct file *filep,
 
   /* Initialize the stream for use with the SLCD CODEC */
 
-  instream.stream.getc = slcd_getstream;
-  instream.stream.nget = 0;
-  instream.buffer      = buffer;
-  instream.nbytes      = len;
+  lib_meminstream(&instream, buffer, len);
 
   /* Prime the pump.  This is messy, but necessary to handle decoration on a
    * character based on any following period or colon.
    */
 
   memset(&state, 0, sizeof(struct slcdstate_s));
-  result = slcd_decode(&instream.stream, &state, &prev, &count);
+  result = slcd_decode(&instream.public, &state, &prev, &count);
 
   lcdinfo("slcd_decode returned result=%d char=%d count=%d\n",
            result, prev, count);
@@ -1209,8 +1173,8 @@ static ssize_t slcd_write(struct file *filep,
 
   /* Now decode and process every byte in the input buffer */
 
-  while ((result = slcd_decode(&instream.stream, &state, &ch, &count)) !=
-         SLCDRET_EOF)
+  while ((result = slcd_decode(&instream.public,
+                               &state, &ch, &count)) != SLCDRET_EOF)
     {
       lcdinfo("slcd_decode returned result=%d char=%d count=%d\n",
               result, ch, count);
diff --git a/boards/mips/pic32mx/sure-pic32mx/src/pic32mx_lcd1602.c b/boards/mips/pic32mx/sure-pic32mx/src/pic32mx_lcd1602.c
index cae80ad845..6ae3d987c6 100644
--- a/boards/mips/pic32mx/sure-pic32mx/src/pic32mx_lcd1602.c
+++ b/boards/mips/pic32mx/sure-pic32mx/src/pic32mx_lcd1602.c
@@ -119,15 +119,6 @@
  * Private Type Definition
  ****************************************************************************/
 
-/* SLCD incoming stream structure */
-
-struct lcd_instream_s
-{
-  struct lib_instream_s stream;
-  const char *buffer;
-  ssize_t nbytes;
-};
-
 /* Global LCD state */
 
 struct lcd1602_2
@@ -147,7 +138,7 @@ struct lcd1602_2
 #ifdef CONFIG_DEBUG_LCD_INFO
 static void lcd_dumpstate(const char *msg);
 static void lcd_dumpstream(const char *msg,
-                           const struct lcd_instream_s *stream);
+                           const struct lib_meminstream_s *stream);
 #else
 #  define lcd_dumpstate(msg)
 #  define lcd_dumpstream(msg, stream)
@@ -245,39 +236,15 @@ static void lcd_dumpstate(const char *msg)
 
 #ifdef CONFIG_DEBUG_LCD_INFO
 static void lcd_dumpstream(const char *msg,
-                           const struct lcd_instream_s *stream)
+                           const struct lib_meminstream_s *stream)
 {
   lcdinfo("%s:\n", msg);
   lcdinfo("  nget: %d nbytes: %d\n",
-          stream->stream.nget, stream->nbytes);
-  lib_dumpbuffer("STREAM", stream->buffer, stream->nbytes);
+          stream->public.nget, stream->buflen);
+  lib_dumpbuffer("STREAM", stream->buffer, stream->buflen);
 }
 #endif
 
-/****************************************************************************
- * Name: lcd_getstream
- *
- * Description:
- *   Get one character from the keyboard.
- *
- ****************************************************************************/
-
-static int lcd_getstream(struct lib_instream_s *instream)
-{
-  struct lcd_instream_s *lcdstream =
-                            (struct lcd_instream_s *)instream;
-
-  DEBUGASSERT(lcdstream && lcdstream->buffer);
-  if (lcdstream->nbytes > 0)
-    {
-      lcdstream->nbytes--;
-      lcdstream->stream.nget++;
-      return (int)*lcdstream->buffer++;
-    }
-
-  return EOF;
-}
-
 /****************************************************************************
  * Name: lcd_brightness
  *
@@ -829,7 +796,7 @@ static ssize_t lcd_read(struct file *filep, char *buffer, size_t len)
 static ssize_t lcd_write(struct file *filep,  const char *buffer,
                          size_t len)
 {
-  struct lcd_instream_s instream;
+  struct lib_meminstream_s instream;
   struct slcdstate_s state;
   enum slcdret_e result;
   uint8_t ch;
@@ -837,18 +804,14 @@ static ssize_t lcd_write(struct file *filep,  const char *buffer,
 
   /* Initialize the stream for use with the SLCD CODEC */
 
-  instream.stream.getc = lcd_getstream;
-  instream.stream.nget = 0;
-  instream.buffer      = buffer;
-  instream.nbytes      = len;
-
+  lib_meminstream(&instream, buffer, len);
   lcd_dumpstream("BEFORE WRITE", &instream);
 
   /* Now decode and process every byte in the input buffer */
 
   memset(&state, 0, sizeof(struct slcdstate_s));
-  while ((result = slcd_decode(&instream.stream,
-         &state, &ch, &count)) != SLCDRET_EOF)
+  while ((result = slcd_decode(&instream.public,
+                               &state, &ch, &count)) != SLCDRET_EOF)
     {
       lcdinfo("slcd_decode returned result=%d char=%d count=%d\n",
               result, ch, count);
diff --git a/drivers/lcd/ht16k33_14seg.c b/drivers/lcd/ht16k33_14seg.c
index e5e0413716..565e569beb 100644
--- a/drivers/lcd/ht16k33_14seg.c
+++ b/drivers/lcd/ht16k33_14seg.c
@@ -111,13 +111,6 @@ struct ht16k33_dev_s
   mutex_t    lock;
 };
 
-struct lcd_instream_s
-{
-  struct lib_instream_s stream;
-  FAR const char *buffer;
-  ssize_t nbytes;
-};
-
 /****************************************************************************
  * Private Function Prototypes
  ****************************************************************************/
@@ -706,29 +699,6 @@ static void lcd_codec_action(FAR struct ht16k33_dev_s *priv,
     }
 }
 
-/****************************************************************************
- * Name: lcd_getstream
- *
- * Description:
- *   Get one character from the LCD codec stream.
- *
- ****************************************************************************/
-
-static int lcd_getstream(FAR struct lib_instream_s *instream)
-{
-  FAR struct lcd_instream_s *lcdstream =
-    (FAR struct lcd_instream_s *)instream;
-
-  if (lcdstream->nbytes > 0)
-    {
-      lcdstream->nbytes--;
-      lcdstream->stream.nget++;
-      return (int)*lcdstream->buffer++;
-    }
-
-  return EOF;
-}
-
 /****************************************************************************
  * Name: lcd_init
  *
@@ -798,7 +768,7 @@ static ssize_t ht16k33_write(FAR struct file *filep, FAR const char *buffer,
 {
   FAR struct inode *inode = filep->f_inode;
   FAR struct ht16k33_dev_s *priv = inode->i_private;
-  struct lcd_instream_s instream;
+  struct lib_meminstream_s instream;
   struct slcdstate_s state;
   enum slcdret_e result;
   uint8_t ch;
@@ -808,16 +778,13 @@ static ssize_t ht16k33_write(FAR struct file *filep, FAR const char *buffer,
 
   /* Initialize the stream for use with the SLCD CODEC */
 
-  instream.stream.getc = lcd_getstream;
-  instream.stream.nget = 0;
-  instream.buffer      = buffer;
-  instream.nbytes      = buflen;
+  lib_meminstream(&instream, buffer, buflen);
 
   /* Now decode and process every byte in the input buffer */
 
   memset(&state, 0, sizeof(struct slcdstate_s));
-  while ((result = slcd_decode(&instream.stream, &state, &ch, &count)) !=
-         SLCDRET_EOF)
+  while ((result = slcd_decode(&instream.public,
+                               &state, &ch, &count)) != SLCDRET_EOF)
     {
       /* Is there some pending scroll? */
 
diff --git a/drivers/lcd/pcf8574_lcd_backpack.c b/drivers/lcd/pcf8574_lcd_backpack.c
index 50cc6a22db..07dd614baf 100644
--- a/drivers/lcd/pcf8574_lcd_backpack.c
+++ b/drivers/lcd/pcf8574_lcd_backpack.c
@@ -83,13 +83,6 @@ struct pcf8574_lcd_dev_s
   mutex_t lock;                              /* mutex */
 };
 
-struct lcd_instream_s
-{
-  struct lib_instream_s stream;
-  FAR const char *buffer;
-  ssize_t nbytes;
-};
-
 /****************************************************************************
  * Private Function Prototypes
  ****************************************************************************/
@@ -971,29 +964,6 @@ static void lcd_codec_action(FAR struct pcf8574_lcd_dev_s *priv,
     }
 }
 
-/****************************************************************************
- * Name: lcd_getstream
- *
- * Description:
- *   Get one character from the LCD codec stream.
- *
- ****************************************************************************/
-
-static int lcd_getstream(FAR struct lib_instream_s *instream)
-{
-  FAR struct lcd_instream_s *lcdstream =
-    (FAR struct lcd_instream_s *)instream;
-
-  if (lcdstream->nbytes > 0)
-    {
-      lcdstream->nbytes--;
-      lcdstream->stream.nget++;
-      return (int)*lcdstream->buffer++;
-    }
-
-  return EOF;
-}
-
 /****************************************************************************
  * Name: lcd_fpos_to_curpos
  *
@@ -1214,7 +1184,7 @@ static ssize_t pcf8574_lcd_write(FAR struct file *filep,
   FAR struct inode *inode = filep->f_inode;
   FAR struct pcf8574_lcd_dev_s *priv =
     (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
-  struct lcd_instream_s instream;
+  struct lib_meminstream_s instream;
   uint8_t row;
   uint8_t col;
   struct slcdstate_s state;
@@ -1226,10 +1196,7 @@ static ssize_t pcf8574_lcd_write(FAR struct file *filep,
 
   /* Initialize the stream for use with the SLCD CODEC */
 
-  instream.stream.getc = lcd_getstream;
-  instream.stream.nget = 0;
-  instream.buffer      = buffer;
-  instream.nbytes      = buflen;
+  lib_meminstream(&instream, buffer, buflen);
 
   /* Get the current cursor position now; we'll keep track of it as we go */
 
@@ -1238,8 +1205,8 @@ static ssize_t pcf8574_lcd_write(FAR struct file *filep,
   /* Now decode and process every byte in the input buffer */
 
   memset(&state, 0, sizeof(struct slcdstate_s));
-  while ((result =
-          slcd_decode(&instream.stream, &state, &ch, &count)) != SLCDRET_EOF)
+  while ((result = slcd_decode(&instream.public,
+                               &state, &ch, &count)) != SLCDRET_EOF)
     {
       if (result == SLCDRET_CHAR)       /* A normal character was returned */
         {
diff --git a/drivers/lcd/st7032.c b/drivers/lcd/st7032.c
index 403e38d964..d57b94c73e 100644
--- a/drivers/lcd/st7032.c
+++ b/drivers/lcd/st7032.c
@@ -71,13 +71,6 @@ struct st7032_dev_s
   mutex_t    lock;
 };
 
-struct lcd_instream_s
-{
-  struct lib_instream_s stream;
-  FAR const char *buffer;
-  ssize_t nbytes;
-};
-
 /****************************************************************************
  * Private Function Prototypes
  ****************************************************************************/
@@ -606,29 +599,6 @@ static void lcd_codec_action(FAR struct st7032_dev_s *priv,
     }
 }
 
-/****************************************************************************
- * Name: lcd_getstream
- *
- * Description:
- *   Get one character from the LCD codec stream.
- *
- ****************************************************************************/
-
-static int lcd_getstream(FAR struct lib_instream_s *instream)
-{
-  FAR struct lcd_instream_s *lcdstream =
-    (FAR struct lcd_instream_s *)instream;
-
-  if (lcdstream->nbytes > 0)
-    {
-      lcdstream->nbytes--;
-      lcdstream->stream.nget++;
-      return (int)*lcdstream->buffer++;
-    }
-
-  return EOF;
-}
-
 /****************************************************************************
  * Name: lcd_init
  *
@@ -720,7 +690,7 @@ static ssize_t st7032_write(FAR struct file *filep, FAR const char *buffer,
 {
   FAR struct inode *inode = filep->f_inode;
   FAR struct st7032_dev_s *priv = inode->i_private;
-  struct lcd_instream_s instream;
+  struct lib_meminstream_s instream;
   struct slcdstate_s state;
   enum slcdret_e result;
   uint8_t ch;
@@ -730,16 +700,13 @@ static ssize_t st7032_write(FAR struct file *filep, FAR const char *buffer,
 
   /* Initialize the stream for use with the SLCD CODEC */
 
-  instream.stream.getc = lcd_getstream;
-  instream.stream.nget = 0;
-  instream.buffer      = buffer;
-  instream.nbytes      = buflen;
+  lib_meminstream(&instream, buffer, buflen);
 
   /* Now decode and process every byte in the input buffer */
 
   memset(&state, 0, sizeof(struct slcdstate_s));
-  while ((result = slcd_decode(&instream.stream, &state, &ch, &count)) !=
-         SLCDRET_EOF)
+  while ((result = slcd_decode(&instream.public,
+                               &state, &ch, &count)) != SLCDRET_EOF)
     {
       /* Is there some pending scroll? */