From 8aba78483226a9904e1e1790853a25f5a08abbd0 Mon Sep 17 00:00:00 2001 From: Mauro Carvalho Chehab Date: Sat, 13 May 2017 07:07:47 -0300 Subject: [PATCH] docs-rst: convert librs book to ReST Use pandoc to convert documentation to ReST by calling Documentation/sphinx/tmplcvt script. Signed-off-by: Mauro Carvalho Chehab --- Documentation/DocBook/Makefile | 2 +- Documentation/DocBook/librs.tmpl | 289 ------------------------------- Documentation/core-api/index.rst | 1 + Documentation/core-api/librs.rst | 212 +++++++++++++++++++++++ 4 files changed, 214 insertions(+), 290 deletions(-) delete mode 100644 Documentation/DocBook/librs.tmpl create mode 100644 Documentation/core-api/librs.rst diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile index baedb14f3b40..0a82f6253682 100644 --- a/Documentation/DocBook/Makefile +++ b/Documentation/DocBook/Makefile @@ -8,7 +8,7 @@ DOCBOOKS := \ lsm.xml \ - mtdnand.xml librs.xml \ + mtdnand.xml \ sh.xml ifeq ($(DOCBOOKS),) diff --git a/Documentation/DocBook/librs.tmpl b/Documentation/DocBook/librs.tmpl deleted file mode 100644 index 94f21361e0ed..000000000000 --- a/Documentation/DocBook/librs.tmpl +++ /dev/null @@ -1,289 +0,0 @@ - - - - - - Reed-Solomon Library Programming Interface - - - - Thomas - Gleixner - -
- tglx@linutronix.de -
- - - - - - 2004 - Thomas Gleixner - - - - - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License version 2 as published by the Free Software Foundation. - - - - 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 - - - - For more details see the file COPYING in the source - distribution of Linux. - - - - - - - - Introduction - - The generic Reed-Solomon Library provides encoding, decoding - and error correction functions. - - - Reed-Solomon codes are used in communication and storage - applications to ensure data integrity. - - - This documentation is provided for developers who want to utilize - the functions provided by the library. - - - - - Known Bugs And Assumptions - - None. - - - - - Usage - - This chapter provides examples of how to use the library. - - - Initializing - - The init function init_rs returns a pointer to an - rs decoder structure, which holds the necessary - information for encoding, decoding and error correction - with the given polynomial. It either uses an existing - matching decoder or creates a new one. On creation all - the lookup tables for fast en/decoding are created. - The function may take a while, so make sure not to - call it in critical code paths. - - -/* the Reed Solomon control structure */ -static struct rs_control *rs_decoder; - -/* Symbolsize is 10 (bits) - * Primitive polynomial is x^10+x^3+1 - * first consecutive root is 0 - * primitive element to generate roots = 1 - * generator polynomial degree (number of roots) = 6 - */ -rs_decoder = init_rs (10, 0x409, 0, 1, 6); - - - - Encoding - - The encoder calculates the Reed-Solomon code over - the given data length and stores the result in - the parity buffer. Note that the parity buffer must - be initialized before calling the encoder. - - - The expanded data can be inverted on the fly by - providing a non-zero inversion mask. The expanded data is - XOR'ed with the mask. This is used e.g. for FLASH - ECC, where the all 0xFF is inverted to an all 0x00. - The Reed-Solomon code for all 0x00 is all 0x00. The - code is inverted before storing to FLASH so it is 0xFF - too. This prevents that reading from an erased FLASH - results in ECC errors. - - - The databytes are expanded to the given symbol size - on the fly. There is no support for encoding continuous - bitstreams with a symbol size != 8 at the moment. If - it is necessary it should be not a big deal to implement - such functionality. - - -/* Parity buffer. Size = number of roots */ -uint16_t par[6]; -/* Initialize the parity buffer */ -memset(par, 0, sizeof(par)); -/* Encode 512 byte in data8. Store parity in buffer par */ -encode_rs8 (rs_decoder, data8, 512, par, 0); - - - - Decoding - - The decoder calculates the syndrome over - the given data length and the received parity symbols - and corrects errors in the data. - - - If a syndrome is available from a hardware decoder - then the syndrome calculation is skipped. - - - The correction of the data buffer can be suppressed - by providing a correction pattern buffer and an error - location buffer to the decoder. The decoder stores the - calculated error location and the correction bitmask - in the given buffers. This is useful for hardware - decoders which use a weird bit ordering scheme. - - - The databytes are expanded to the given symbol size - on the fly. There is no support for decoding continuous - bitstreams with a symbolsize != 8 at the moment. If - it is necessary it should be not a big deal to implement - such functionality. - - - - - Decoding with syndrome calculation, direct data correction - - -/* Parity buffer. Size = number of roots */ -uint16_t par[6]; -uint8_t data[512]; -int numerr; -/* Receive data */ -..... -/* Receive parity */ -..... -/* Decode 512 byte in data8.*/ -numerr = decode_rs8 (rs_decoder, data8, par, 512, NULL, 0, NULL, 0, NULL); - - - - - - Decoding with syndrome given by hardware decoder, direct data correction - - -/* Parity buffer. Size = number of roots */ -uint16_t par[6], syn[6]; -uint8_t data[512]; -int numerr; -/* Receive data */ -..... -/* Receive parity */ -..... -/* Get syndrome from hardware decoder */ -..... -/* Decode 512 byte in data8.*/ -numerr = decode_rs8 (rs_decoder, data8, par, 512, syn, 0, NULL, 0, NULL); - - - - - - Decoding with syndrome given by hardware decoder, no direct data correction. - - - Note: It's not necessary to give data and received parity to the decoder. - - -/* Parity buffer. Size = number of roots */ -uint16_t par[6], syn[6], corr[8]; -uint8_t data[512]; -int numerr, errpos[8]; -/* Receive data */ -..... -/* Receive parity */ -..... -/* Get syndrome from hardware decoder */ -..... -/* Decode 512 byte in data8.*/ -numerr = decode_rs8 (rs_decoder, NULL, NULL, 512, syn, 0, errpos, 0, corr); -for (i = 0; i < numerr; i++) { - do_error_correction_in_your_buffer(errpos[i], corr[i]); -} - - - - - Cleanup - - The function free_rs frees the allocated resources, - if the caller is the last user of the decoder. - - -/* Release resources */ -free_rs(rs_decoder); - - - - - - - Structures - - This chapter contains the autogenerated documentation of the structures which are - used in the Reed-Solomon Library and are relevant for a developer. - -!Iinclude/linux/rslib.h - - - - Public Functions Provided - - This chapter contains the autogenerated documentation of the Reed-Solomon functions - which are exported. - -!Elib/reed_solomon/reed_solomon.c - - - - Credits - - The library code for encoding and decoding was written by Phil Karn. - - - Copyright 2002, Phil Karn, KA9Q - May be used under the terms of the GNU General Public License (GPL) - - - The wrapper functions and interfaces are written by Thomas Gleixner. - - - Many users have provided bugfixes, improvements and helping hands for testing. - Thanks a lot. - - - The following people have contributed to this document: - - - Thomas Gleixnertglx@linutronix.de - - - diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst index 62abd36bfffb..0606be3a3111 100644 --- a/Documentation/core-api/index.rst +++ b/Documentation/core-api/index.rst @@ -19,6 +19,7 @@ Core utilities workqueue genericirq flexible-arrays + librs Interfaces for kernel debugging =============================== diff --git a/Documentation/core-api/librs.rst b/Documentation/core-api/librs.rst new file mode 100644 index 000000000000..6010f5bc5bf9 --- /dev/null +++ b/Documentation/core-api/librs.rst @@ -0,0 +1,212 @@ +========================================== +Reed-Solomon Library Programming Interface +========================================== + +:Author: Thomas Gleixner + +Introduction +============ + +The generic Reed-Solomon Library provides encoding, decoding and error +correction functions. + +Reed-Solomon codes are used in communication and storage applications to +ensure data integrity. + +This documentation is provided for developers who want to utilize the +functions provided by the library. + +Known Bugs And Assumptions +========================== + +None. + +Usage +===== + +This chapter provides examples of how to use the library. + +Initializing +------------ + +The init function init_rs returns a pointer to an rs decoder structure, +which holds the necessary information for encoding, decoding and error +correction with the given polynomial. It either uses an existing +matching decoder or creates a new one. On creation all the lookup tables +for fast en/decoding are created. The function may take a while, so make +sure not to call it in critical code paths. + +:: + + /* the Reed Solomon control structure */ + static struct rs_control *rs_decoder; + + /* Symbolsize is 10 (bits) + * Primitive polynomial is x^10+x^3+1 + * first consecutive root is 0 + * primitive element to generate roots = 1 + * generator polynomial degree (number of roots) = 6 + */ + rs_decoder = init_rs (10, 0x409, 0, 1, 6); + + +Encoding +-------- + +The encoder calculates the Reed-Solomon code over the given data length +and stores the result in the parity buffer. Note that the parity buffer +must be initialized before calling the encoder. + +The expanded data can be inverted on the fly by providing a non-zero +inversion mask. The expanded data is XOR'ed with the mask. This is used +e.g. for FLASH ECC, where the all 0xFF is inverted to an all 0x00. The +Reed-Solomon code for all 0x00 is all 0x00. The code is inverted before +storing to FLASH so it is 0xFF too. This prevents that reading from an +erased FLASH results in ECC errors. + +The databytes are expanded to the given symbol size on the fly. There is +no support for encoding continuous bitstreams with a symbol size != 8 at +the moment. If it is necessary it should be not a big deal to implement +such functionality. + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6]; + /* Initialize the parity buffer */ + memset(par, 0, sizeof(par)); + /* Encode 512 byte in data8. Store parity in buffer par */ + encode_rs8 (rs_decoder, data8, 512, par, 0); + + +Decoding +-------- + +The decoder calculates the syndrome over the given data length and the +received parity symbols and corrects errors in the data. + +If a syndrome is available from a hardware decoder then the syndrome +calculation is skipped. + +The correction of the data buffer can be suppressed by providing a +correction pattern buffer and an error location buffer to the decoder. +The decoder stores the calculated error location and the correction +bitmask in the given buffers. This is useful for hardware decoders which +use a weird bit ordering scheme. + +The databytes are expanded to the given symbol size on the fly. There is +no support for decoding continuous bitstreams with a symbolsize != 8 at +the moment. If it is necessary it should be not a big deal to implement +such functionality. + +Decoding with syndrome calculation, direct data correction +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6]; + uint8_t data[512]; + int numerr; + /* Receive data */ + ..... + /* Receive parity */ + ..... + /* Decode 512 byte in data8.*/ + numerr = decode_rs8 (rs_decoder, data8, par, 512, NULL, 0, NULL, 0, NULL); + + +Decoding with syndrome given by hardware decoder, direct data correction +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6], syn[6]; + uint8_t data[512]; + int numerr; + /* Receive data */ + ..... + /* Receive parity */ + ..... + /* Get syndrome from hardware decoder */ + ..... + /* Decode 512 byte in data8.*/ + numerr = decode_rs8 (rs_decoder, data8, par, 512, syn, 0, NULL, 0, NULL); + + +Decoding with syndrome given by hardware decoder, no direct data correction. +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Note: It's not necessary to give data and received parity to the +decoder. + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6], syn[6], corr[8]; + uint8_t data[512]; + int numerr, errpos[8]; + /* Receive data */ + ..... + /* Receive parity */ + ..... + /* Get syndrome from hardware decoder */ + ..... + /* Decode 512 byte in data8.*/ + numerr = decode_rs8 (rs_decoder, NULL, NULL, 512, syn, 0, errpos, 0, corr); + for (i = 0; i < numerr; i++) { + do_error_correction_in_your_buffer(errpos[i], corr[i]); + } + + +Cleanup +------- + +The function free_rs frees the allocated resources, if the caller is +the last user of the decoder. + +:: + + /* Release resources */ + free_rs(rs_decoder); + + +Structures +========== + +This chapter contains the autogenerated documentation of the structures +which are used in the Reed-Solomon Library and are relevant for a +developer. + +.. kernel-doc:: include/linux/rslib.h + :internal: + +Public Functions Provided +========================= + +This chapter contains the autogenerated documentation of the +Reed-Solomon functions which are exported. + +.. kernel-doc:: lib/reed_solomon/reed_solomon.c + :export: + +Credits +======= + +The library code for encoding and decoding was written by Phil Karn. + +:: + + Copyright 2002, Phil Karn, KA9Q + May be used under the terms of the GNU General Public License (GPL) + + +The wrapper functions and interfaces are written by Thomas Gleixner. + +Many users have provided bugfixes, improvements and helping hands for +testing. Thanks a lot. + +The following people have contributed to this document: + +Thomas Gleixner\ tglx@linutronix.de