Hi,
Please consider my proposal:
1 - A linux wide standard notation for seven segment displays.
2 - A standard method for accessing 7-segments character sets
from user space, by introducing the "map_seg7" sysfs file.
3 - An ASCII based 7-segments character set for reuse by (potential)
other LCD drivers.
4 - A location for header files, dedicated to conversions and "map's"
and tables.
Background:
I am currently working on a LDC driver for an USB-Phone, unfortunately
each segment must be driven seperately. Therefore I had some need for a
translation map that could convert ASCII chars into a 7-segment
notation.
I know this 7-segments stuff probably won't be used widespread much but it
could be important to have similar projects use the same notation, and
use the same concepts.
This in oder to make user space programmers more happy. At least it
would be worth to keep a small include file, no need for abstaction
layers in the kernel.
1 - Notation
Make things potential interoperable, your character sets will be
portable to other LCD devices.
+-a-+
f b
+-g-+ => encodes to => MSb 76543210 LSb
e c gfedcba
+-d-+ bit7 is reserved.
2 - A standard method for accessing 7-segments character sets
If a map should be accesible from userspace we should give it a
standard sysfs file name: "map_seg7" is proposed.
At least we know then where to look.
If multiple maps are needed by a device (god forbid) they should be indexed
like:
map_seg7.0
map_seg7.1
map_seg7.2 ...
3 - An ASCII based 7-segments character set for reuse by (potential)
other LCD drivers.
Spare yourself the labour of defining this yourself...!
4 - A location for header files, dedicated to conversions and "map's"
and tables.
A programmer should know where to look in order to save his time,
therfore the name should start with map_ and is possibly located
in a seperate general include directory, proposed is:
include/linux/map/map_to_7segment.h
for this particular instance. However it could be a good location
also for:
.../map_dram_timings.h
.../map_mode_line_specs.h
.../map_...
What do you think?
Regards,
Henk Vergonet
--- map_to_7segment.h.orig 2005-05-31 22:42:17.000000000 +0200
+++ map_to_7segment.h 2005-05-31 22:57:16.000000000 +0200
@@ -0,0 +1,189 @@
+/*
+ * include/map/map_to_7segment.h
+ *
+ * Copyright (c) 2005 Henk Vergonet <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef MAP_TO_7SEGMENT_H
+#define MAP_TO_7SEGMENT_H
+
+/* This file provides translation primitives and tables for the conversion
+ * of (ASCII) characters to a 7-segments notation.
+ *
+ * The 7 segment's notation below s used as standard, as it looks like it is
+ * the most commonly used.
+ *
+ * See: http://en.wikipedia.org/wiki/Seven_segment_display
+ *
+ * Notation: +-a-+
+ * f b
+ * +-g-+
+ * e c
+ * +-d-+
+ *
+ * Usage:
+ *
+ * Register a map variable, and fill it with a character set:
+ * static SEG7_DEFAULT_MAP(map_seg7);
+ *
+ *
+ * Then use for conversion:
+ * seg7 = map_to_seg7(&map_seg7, some_char);
+ * ...
+ *
+ * In device drivers it is recommended to make the map accessible via the
+ * sysfs interface, please use the MAP_SEG7_SYSFS_FILE naming convention:
+ *
+ * static ssize_t show_map(struct device *dev, char *buf) {
+ * memcpy(buf, &map_seg7, sizeof(map_seg7));
+ * return sizeof(map_seg7);
+ * }
+ * static ssize_t store_map(struct device *dev, const char *buf, size_t cnt) {
+ * memcpy(&map_seg7, buf, cnt > sizeof(map_seg7) ? sizeof(map_seg7) : cnt);
+ * return cnt;
+ * }
+ * static DEVICE_ATTR(map_seg7, PERMS_RW, show_map, store_map);
+ *
+ * History:
+ * 2005-05-31 RFC [email protected]
+ */
+#include <linux/errno.h>
+
+
+#define BIT_SEG7_A 0
+#define BIT_SEG7_B 1
+#define BIT_SEG7_C 2
+#define BIT_SEG7_D 3
+#define BIT_SEG7_E 4
+#define BIT_SEG7_F 5
+#define BIT_SEG7_G 6
+#define BIT_SEG7_RESERVED 7
+
+struct seg7_conversion_map {
+ unsigned char table[128];
+};
+
+static inline int map_to_seg7(struct seg7_conversion_map *map, int c)
+{
+ return c & 0x7f ? map->table[c] : -EINVAL;
+}
+
+#define SEG7_CONVERSION_MAP(_name, _map) \
+ struct seg7_conversion_map _name = { .table = { _map } }
+
+/*
+ * It is recommended to use a facility that allows user space to redefine
+ * custom character sets for LCD devices. Please use a sysfs interface
+ * as described above.
+ */
+#define MAP_TO_SEG7_SYSFS_FILE "map_seg7"
+
+/*******************************************************************************
+ * ASCII conversion table
+ ******************************************************************************/
+
+#define _SEG7(l,a,b,c,d,e,f,g) \
+ ( a<<BIT_SEG7_A | b<<BIT_SEG7_B | c<<BIT_SEG7_C | d<<BIT_SEG7_D | \
+ e<<BIT_SEG7_E | f<<BIT_SEG7_F | g<<BIT_SEG7_G )
+
+#define _MAP_0_32_ASCII_SEG7_NON_PRINTABLE \
+ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+
+#define _MAP_33_47_ASCII_SEG7_SYMBOL \
+ _SEG7('!',0,0,0,0,1,1,0), _SEG7('"',0,1,0,0,0,1,0), _SEG7('#',0,1,1,0,1,1,0),\
+ _SEG7('$',1,0,1,1,0,1,1), _SEG7('%',0,0,1,0,0,1,0), _SEG7('&',1,0,1,1,1,1,1),\
+ _SEG7('\'',0,0,0,0,0,1,0),_SEG7('(',1,0,0,1,1,1,0), _SEG7(')',1,1,1,1,0,0,0),\
+ _SEG7('*',0,1,1,0,1,1,1), _SEG7('+',0,1,1,0,0,0,1), _SEG7(',',0,0,0,0,1,0,0),\
+ _SEG7('-',0,0,0,0,0,0,1), _SEG7('.',0,0,0,0,1,0,0), _SEG7('/',0,1,0,0,1,0,1),
+
+#define _MAP_48_57_ASCII_SEG7_NUMERIC \
+ _SEG7('0',1,1,1,1,1,1,0), _SEG7('1',0,1,1,0,0,0,0), _SEG7('2',1,1,0,1,1,0,1),\
+ _SEG7('3',1,1,1,1,0,0,1), _SEG7('4',0,1,1,0,0,1,1), _SEG7('5',1,0,1,1,0,1,1),\
+ _SEG7('6',1,0,1,1,1,1,1), _SEG7('7',1,1,1,0,0,0,0), _SEG7('8',1,1,1,1,1,1,1),\
+ _SEG7('9',1,1,1,1,0,1,1),
+
+#define _MAP_58_64_ASCII_SEG7_SYMBOL \
+ _SEG7(':',0,0,0,1,0,0,1), _SEG7(';',0,0,0,1,0,0,1), _SEG7('<',1,0,0,0,0,1,1),\
+ _SEG7('=',0,0,0,1,0,0,1), _SEG7('>',1,1,0,0,0,0,1), _SEG7('?',1,1,1,0,0,1,0),\
+ _SEG7('@',1,1,0,1,1,1,1),
+
+#define _MAP_65_90_ASCII_SEG7_ALPHA_UPPR \
+ _SEG7('A',1,1,1,0,1,1,1), _SEG7('B',1,1,1,1,1,1,1), _SEG7('C',1,0,0,1,1,1,0),\
+ _SEG7('D',1,1,1,1,1,1,0), _SEG7('E',1,0,0,1,1,1,1), _SEG7('F',1,0,0,0,1,1,1),\
+ _SEG7('G',1,1,1,1,0,1,1), _SEG7('H',0,1,1,0,1,1,1), _SEG7('I',0,1,1,0,0,0,0),\
+ _SEG7('J',0,1,1,1,0,0,0), _SEG7('K',0,1,1,0,1,1,1), _SEG7('L',0,0,0,1,1,1,0),\
+ _SEG7('M',1,1,1,0,1,1,0), _SEG7('N',1,1,1,0,1,1,0), _SEG7('O',1,1,1,1,1,1,0),\
+ _SEG7('P',1,1,0,0,1,1,1), _SEG7('Q',1,1,1,1,1,1,0), _SEG7('R',1,1,1,0,1,1,1),\
+ _SEG7('S',1,0,1,1,0,1,1), _SEG7('T',0,0,0,1,1,1,1), _SEG7('U',0,1,1,1,1,1,0),\
+ _SEG7('V',0,1,1,1,1,1,0), _SEG7('W',0,1,1,1,1,1,1), _SEG7('X',0,1,1,0,1,1,1),\
+ _SEG7('Y',0,1,1,0,0,1,1), _SEG7('Z',1,1,0,1,1,0,1),
+
+#define _MAP_91_96_ASCII_SEG7_SYMBOL \
+ _SEG7('[',1,0,0,1,1,1,0), _SEG7('\\',0,0,1,0,0,1,1),_SEG7(']',1,1,1,1,0,0,0),\
+ _SEG7('^',1,1,0,0,0,1,0), _SEG7('_',0,0,0,1,0,0,0), _SEG7('`',0,1,0,0,0,0,0),
+
+#define _MAP_97_122_ASCII_SEG7_ALPHA_LOWER \
+ _SEG7('A',1,1,1,0,1,1,1), _SEG7('b',0,0,1,1,1,1,1), _SEG7('c',0,0,0,1,1,0,1),\
+ _SEG7('d',0,1,1,1,1,0,1), _SEG7('E',1,0,0,1,1,1,1), _SEG7('F',1,0,0,0,1,1,1),\
+ _SEG7('G',1,1,1,1,0,1,1), _SEG7('h',0,0,1,0,1,1,1), _SEG7('i',0,0,1,0,0,0,0),\
+ _SEG7('j',0,0,1,1,0,0,0), _SEG7('k',0,0,1,0,1,1,1), _SEG7('L',0,0,0,1,1,1,0),\
+ _SEG7('M',1,1,1,0,1,1,0), _SEG7('n',0,0,1,0,1,0,1), _SEG7('o',0,0,1,1,1,0,1),\
+ _SEG7('P',1,1,0,0,1,1,1), _SEG7('q',1,1,1,0,0,1,1), _SEG7('r',0,0,0,0,1,0,1),\
+ _SEG7('S',1,0,1,1,0,1,1), _SEG7('T',0,0,0,1,1,1,1), _SEG7('u',0,0,1,1,1,0,0),\
+ _SEG7('v',0,0,1,1,1,0,0), _SEG7('W',0,1,1,1,1,1,1), _SEG7('X',0,1,1,0,1,1,1),\
+ _SEG7('y',0,1,1,1,0,1,1), _SEG7('Z',1,1,0,1,1,0,1),
+
+#define _MAP_123_126_ASCII_SEG7_SYMBOL \
+ _SEG7('{',1,0,0,1,1,1,0), _SEG7('|',0,0,0,0,1,1,0), _SEG7('}',1,1,1,1,0,0,0),\
+ _SEG7('~',1,0,0,0,0,0,0),
+
+/* Maps */
+
+/* This set tries to map as close as possible to the visible characteristics
+ * of the ASCII symbol, lowercase and uppercase letters may differ in
+ * presentation on the display.
+ */
+#define MAP_ASCII7SEG_ALPHANUM \
+ _MAP_0_32_ASCII_SEG7_NON_PRINTABLE \
+ _MAP_33_47_ASCII_SEG7_SYMBOL \
+ _MAP_48_57_ASCII_SEG7_NUMERIC \
+ _MAP_58_64_ASCII_SEG7_SYMBOL \
+ _MAP_65_90_ASCII_SEG7_ALPHA_UPPR \
+ _MAP_91_96_ASCII_SEG7_SYMBOL \
+ _MAP_97_122_ASCII_SEG7_ALPHA_LOWER \
+ _MAP_123_126_ASCII_SEG7_SYMBOL
+
+/* This set tries to map as close as possible to the symbolic characteristics
+ * of the ASCII character for maximum discrimination.
+ * For now this means all alpha chars are in lower case representations.
+ * (This for example facilitates the use of hex numbers with uppercase input.)
+ */
+#define MAP_ASCII7SEG_ALPHANUM_LC \
+ _MAP_0_32_ASCII_SEG7_NON_PRINTABLE \
+ _MAP_33_47_ASCII_SEG7_SYMBOL \
+ _MAP_48_57_ASCII_SEG7_NUMERIC \
+ _MAP_58_64_ASCII_SEG7_SYMBOL \
+ _MAP_97_122_ASCII_SEG7_ALPHA_LOWER \
+ _MAP_91_96_ASCII_SEG7_SYMBOL \
+ _MAP_97_122_ASCII_SEG7_ALPHA_LOWER \
+ _MAP_123_126_ASCII_SEG7_SYMBOL
+
+#define SEG7_DEFAULT_MAP(_name) \
+ SEG7_CONVERSION_MAP(_name,MAP_ASCII7SEG_ALPHANUM)
+
+#endif /* MAP_TO_7SEGMENT_H */
+
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