diff options
Diffstat (limited to 'ld/ld.texi')
| -rw-r--r-- | ld/ld.texi | 498 |
1 files changed, 4 insertions, 494 deletions
@@ -5302,7 +5302,7 @@ __stop_SECNAME, where SECNAME is the name of the section. These indicate the start address and end address of the output section respectively. Note: most section names are not representable as C identifiers because they contain a @samp{.} character. -@page + @node Output Section Data @subsection Output Section Data @cindex data @@ -5353,28 +5353,10 @@ whereas this will work: @smallexample SECTIONS @{@ .text : @{@ *(.text) ; LONG(1) @}@ .data : @{@ *(.data) @}@ @}@ @end smallexample -@page + @cindex output section strings @kindex ASCII (@var{expression}) ``@var{string}'' @kindex ASCIZ ``@var{string}'' -@code{ASCII strings} -@sp 1 -@multitable @columnfractions .25 .20 .30 .20 .05 -@item -ASCIZ -@tab -@tab -"<string" -@tab -@item -ASCII -@tab -(<size>) -@tab -"<string" -@tab -@end multitable -@sp 1 You can include a zero-terminated string in an output section by using @code{ASCIZ}. The keyword is followed by a string which is stored at the current value of the location counter including adding a zero byte @@ -5399,490 +5381,18 @@ it must be enclosed in double quotes. The string can have C escape characters like '\n', '\r', '\t' and octal numbers. The '\"' escape is not supported. Nor are escaped hex values. -@sp 2 + Example 1: This is string of 16 characters and will create a 32 byte area: @smallexample ASCII (32) "This is 16 bytes" @end smallexample -@sp 2 + Example 2: This is a string of 16 characters and will create a 17 byte area: @smallexample ASCIZ "This is 16 bytes" @end smallexample -@page -@cindex output section strings -@kindex DIGEST "<label>[#<endian>]" "CRC64-ECMA" (@var{expr}, @var{expr}) -@kindex DIGEST "<label>[#<endian>]" "CRC64-ISO" (@var{expr}, @var{expr}) -@kindex DIGEST "<label>[#<endian>]" "CRC64-ISO-R" (@var{expr}, @var{expr}) -@kindex DIGEST "<label>[#<endian>]" "CRC64-WE" (@var{expr}, @var{expr}) -@kindex DIGEST "<label>[#<endian>]" "CRC64-XZ" (@var{expr}, @var{expr}) -@kindex DIGEST "<label>[#<endian>]" "CRC32" (@var{expr}, @var{expr}) -@kindex DIGEST "<label>[#<endian>]" POLY (@var{<parms>}) (@var{expr}, @var{expr}) - -@code{CRC Calculation} -@sp 1 -@multitable @columnfractions .20 .27 .28 .25 -@item -DIGEST -@tab -"<label>[#<endian>]" -@tab -"CRC32" -@tab -(start, end) -@item -DIGEST -@tab -"<label>[#<endian>]" -@tab -"CRC64-ECMA" -@tab -(start, end) -@item -DIGEST -@tab -"<label>[#<endian>]" -@tab -"CRC64-GO-ISO" -@tab -(start, end) -@item -DIGEST -@tab -"<label>[#<endian>]" -@tab -"CRC64-GO-ISO-R" -@tab -(start, end) -@item -DIGEST -@tab -"<label>[#<endian>]" -@tab -"CRC64-WE" -@tab -(start, end) -@item -DIGEST -@tab -"<label>[#<endian>]" -@tab -"CRC64-XZ" -@tab -(start, end) -@item -DIGEST -@tab -"<label>[#<endian>]" -@tab -POLY (<params>) -@tab -(start, end) -@item -DIGEST TABLE -@tab -"<label>[#<endian>]" -@tab -@tab -(start, end) -@end multitable - -You can calculate the CRC of a part of an output section through the -@code{DIGEST} command. The default section is the @code{".text"} section. -The commands take parameters for a label, a @code{polynome} and then two more, -specifying range of the checked area. The end address is the first address -past the checked area. - -The checksum is generated in little endian format, but this can be overridden by -adding a @code{#BE} or @code{#LE} modifier to the label string. -The generated label does not include the modifier. The endian can also be -specified on the command line using @code{-BE} or @code{-LE}. - -@sp 1 -There is one predefined 32-bit polynome - -@multitable @columnfractions .3 .4 .4 -@item -* @code{CRC32} -@tab -@code{0x04C11DB7} -@tab -@end multitable - -There are five predefined 64-bit polynomes - -@multitable @columnfractions .3 .4 .4 -@item -* @code{CRC64-ECMA} -@tab -@code{0x42F0E1EBA9EA3693} -@tab -@item -* @code{CRC64-ISO} -@tab -@code{0x000000000000001B} -@tab -@item -* @code{CRC64-ISO-R} -@tab -@code{0xD800000000000000} -@tab -@item -* @code{CRC64-WE} -@tab -@code{0x42F0E1EBA9EA3693} -@tab -@item -* @code{CRC64-XZ} -@tab -@code{0x42F0E1EBA9EA3693} -@tab -@end multitable -@sp 1 -You can also select your own @code{polynome} using the @code{DIGEST POLY}. - -It takes the following @code{parameters} separated by commas. - -@multitable @columnfractions .3 .7 -@item -@code{size} -@tab -size of CRC (32 or 64) -@item -@code{polynome} -@tab -@item -@code{initial} -@tab -initial value of crc before calculation -@item -@code{xor} -@tab -xor result before return -@item -@code{input reflect} -@tab -bitreverse input data -@item -@code{output reflect} -@tab -bitreverse result (before xor'ing) -@item -@code{reciprocal} -@tab -bitreverse polynome before generating table -@end multitable - -The parameters are explained in detail in - -@code{http://www.sunshine2k.de/articles/coding/crc/understanding_crc.html} - -Some of the predefined polynomes are the same, but differs in the other -parameters. -@page -The 32-bit <polynome> command defines the following global symbols. - -@multitable @columnfractions .3 .7 -@item -@code{___CRC32___} -@tab -address of the CRC32 checksum -@item -@code{___CRC32_START___} -@tab -first address in the checked area. -@item -@code{___CRC32_END___} -@tab -first address past the checked area. -@end multitable -@sp 2 -The 64-bit <polynome> command defines the following global symbols. - -@multitable @columnfractions .3 .7 -@item -@code{___CRC64___} -@tab -address of the CRC64 checksum -@item -@code{___CRC64_START___} -@tab -first address in the checked area. -@item -@code{___CRC64_END___} -@tab -first address past the checked area. -@end multitable -@sp 2 -Note: The generated CRC value must be stored outside the checked area. -@sp 2 -Example 1: This request a CRC check using the @code{ECMA} algorithm - -@smallexample - DIGEST "C64" "CRC64-ECMA" (START_CHECK,END_TEXT) -@end smallexample - -The user can retrieve the CRC value through the @code{C64} label. -@sp 2 -Example 2: This request a CRC check using the @code{ISO} algorithm - - The checksum is stored as big endian - -@smallexample - DIGEST "C64I#BE" "CRC64-ISO" (START_CHECK,END_TEXT) -@end smallexample - -The user can retrieve the big endian CRC value through the @code{C64I} label. -@sp 2 -Example 3: This request a CRC check using a user defined @code{polynome} - - The setup is the "CRC32" algorithm - -@smallexample - DIGEST "CRC" POLY (32, 0x04C11DB7,~0,~0,1,1,0) (START_CHECK,END_TEXT) -@end smallexample - -The user can retrieve the CRC value through the @code{CRC} label. -@sp 2 -Example 4: This request a CRC check using the @code{CRC32} polynome - -@smallexample - DIGEST "C32.SE" (START_CHECK,END_TEXT) -@end smallexample - -The user can retrieve the CRC value through the @code{C32} label. - -@page -@cindex output section strings -@kindex DIGEST TABLE "<label>[#<endian>]" -@page -The @code{DIGEST TABLE} command creates a 1 or 2 kByte table for a table-driven -CRC calculation. This speeds up the CRC calculation over a non-table-driver -version since you can handle 8 bits at a time, instead of 1 bit. - -The table generated is for the @code{polynome} selected using a -@code{DIGEST <polynome>} command. - -The command will define the label supplied as a parameter. -The table will be in small endian, unless the @code{.BE} or @code{.LE} extension -is given to the label. -It also defines a symbol based on the size of the polynome. - -@enumerate -@item -@code{___CRC32_TABLE___} address of the CRC32 table, or -@item -@code{___CRC64_TABLE___} address of the CRC64 table -@end enumerate - -@sp 2 -Example 1: Generate a 1 kB table - -(assuming a previous @code{DIGEST "CRC32"} command) - -@smallexample - DIGEST TABLE "crc_tab32" -@end smallexample - -The user must declare @code{extern uint32_t *crc_tab32;} in his code. -@sp 2 -Example 2: Generate a 2 kB table in big endian format. - -(assuming a previous @code{DIGEST "CRC64-###"} command) - -@smallexample - DIGEST TABLE "crc_tab64.be" -@end smallexample - -The user must declare @code{extern uint64_t *crc_tab64;} in his code. - -Using the tables: - The user must include CRC code in the application to test the CRC -@sp 2 - -@multitable @columnfractions .15 .85 -@item -Example 1: -@tab -Calculating CRC-64 -@end multitable -@sp 1 -@multitable @columnfractions .05 .95 -@item -@tab -Copyright (c) 2016 Lammert Bies -@item -@tab -Copyright (c) 2021 Bastian Molkenthin -@item -@tab -Copyright (c) 2023 Ulf Samuelsson -@end multitable -@sp 2 -@smallexample -#define SHIFT(t) ((sizeof(t)-1)*8) -uint64_t calc_crc64 - (algorithm_desc_t * dsc, const unsigned char *input_str, size_t num_bytes) -@{ - uint64_t crc; - const unsigned char *ptr; - uint64_t *crc_tab = dsc->crc_tab; - uint64_t index; - - if ((ptr = input_str) == NULL) - return 0; - - if (crc_tab == NULL) - return 0; - - - crc = dsc->initial; - if (dsc->reciprocal) - @{ - for (uint32_t i = 0; i < num_bytes; i++) - @{ - index = ((crc >> 0) ^ (uint64_t) * ptr++) & 0x00000000000000FFull; - crc = (crc >> 8) ^ crc_tab[index]; - @} - @} - else - @{ - uint32_t shift = SHIFT (uint64_t); - for (uint32_t i = 0; i < num_bytes; i++) - @{ - const unsigned char c = *ptr++; - uint64_t rc = (uint64_t) (dsc->ireflect ? reflect8 (c) : c); - crc = (crc ^ (rc << shift)); - index = (uint32_t) (crc >> shift); - crc = (crc << 8); - crc = (crc ^ (crc_tab[index])); - @} - @} - crc = (dsc->oreflect ? reflect64 (crc) : crc); - crc = crc ^ dsc->xor_val; - return crc; -@} /* calc_crc64 */ -@end smallexample -@page -@multitable @columnfractions .15 .85 -@item -Example 2: -@tab -Calculating CRC-32 -@end multitable -@sp 1 -@multitable @columnfractions .05 .95 -@item -@tab -Copyright (c) 2016 Lammert Bies -@item -@tab -Copyright (c) 2021 Bastian Molkenthin -@item -@tab -Copyright (c) 2023 Ulf Samuelsson -@end multitable -@sp 2 -@smallexample -#define SHIFT(t) ((sizeof(t)-1)*8) -uint32_t -calc_crc32 (algorithm_desc_t * dsc, const unsigned char *input_str, - size_t num_bytes) -@{ - uint32_t crc; - const unsigned char *ptr; - uint32_t index; - uint32_t *crc_tab = dsc->crc_tab; - - if ((ptr = input_str) == NULL) - return 0; - - if (crc_tab == NULL) - return 0; - - crc = dsc->initial; - - if (dsc->reciprocal) - @{ - for (uint32_t i = 0; i < num_bytes; i++) - @{ - index = ((crc >> 0) ^ (uint32_t) * ptr++) & 0x000000FFul; - crc = (crc >> 8) ^ crc_tab[index]; - @} - @} - else - @{ - uint32_t shift = SHIFT (uint32_t); - for (uint32_t i = 0; i < num_bytes; i++) - @{ - const unsigned char c = *ptr++; - uint32_t rc = (uint32_t) (dsc->ireflect ? reflect8 (c) : c); - crc = (crc ^ (rc << shift)); - index = (uint32_t) (crc >> shift); - crc = (crc << 8); - crc = (crc ^ (crc_tab[index])); - @} - @} - crc = (dsc->oreflect ? reflect32 (crc) : crc); - crc = crc ^ dsc->xor_val; - return crc; -@} /* calc_crc32 */ -@end smallexample -@page -@multitable @columnfractions .15 .85 -@item -Example 3: -@tab -Calculating CRC-32 using optimized routine -@end multitable -@sp 1 -@multitable @columnfractions .05 .95 -@item -@tab -Copyright (c) 2016 Lammert Bies -@item -@tab -Copyright (c) 2021 Bastian Molkenthin -@item -@tab -Copyright (c) 2023 Ulf Samuelsson -@end multitable -@sp 2 -@smallexample -#define SHIFT(t) ((sizeof(t)-1)*8) -extern uint32_t *crc_tab; - -uint32_t -calc_crc32 (const unsigned char *input_str, size_t num_bytes) -@{ - uint32_t crc; - const unsigned char *ptr; - uint32_t index; - uint32_t shift = SHIFT (uint32_t); - - if ((ptr = input_str) == NULL) - return 0; - - crc = 0xFFFFFFFF; - for (uint32_t i = 0; i < num_bytes; i++) - @{ - const unsigned char c = *ptr++; - crc = (crc ^ (c << shift)); - index = (uint32_t) (crc >> shift); - crc = (crc << 8); - crc = (crc ^ (crc_tab[index])); - @} - return crc ^ 0xFFFFFFFF; -@} /* calc_crc32 */ -@end smallexample -@page -@cindex output section strings -@kindex TIMESTAMP - -The @code{TIMESTAMP} command creates 64-bit integer with the number of seconds -since Epoch (1970-01-01 00:00). @kindex FILL(@var{expression}) @cindex holes, filling |