Document the format specifier codes used by U-Boot's printf() implementation.
Signed-off-by: Heinrich Schuchardt heinrich.schuchardt@canonical.com --- doc/develop/index.rst | 1 + doc/develop/printf.rst | 132 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 133 insertions(+) create mode 100644 doc/develop/printf.rst
diff --git a/doc/develop/index.rst b/doc/develop/index.rst index 9592d193fc..c84b10ea88 100644 --- a/doc/develop/index.rst +++ b/doc/develop/index.rst @@ -21,6 +21,7 @@ Implementation logging makefiles menus + printf uefi/index version
diff --git a/doc/develop/printf.rst b/doc/develop/printf.rst new file mode 100644 index 0000000000..6a1266618e --- /dev/null +++ b/doc/develop/printf.rst @@ -0,0 +1,132 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +Printf() format codes +===================== + +Integer types +------------- + +Integer qualifiers +'''''''''''''''''' + +Inter qualifers describe how integer types are passed as arguments. + +no specifier + int (used for bool, enum, short, int) + +%h + int, consider only the low 16 bits + +%l + long + +%ll, %L + long long + +%t + ptr_diff_t + +%z, %Z + size_t, ssize_t + +Format specifiers +''''''''''''''''' + +Format specifiers control the output. + +%d + signed decimal + +%u + unsigned decimal + +%x + lower case hexadecimal + +%X + upper case hexadecimal + +The following tables shows the correct combinations of qulifiers and specifiers +for the individual integer types. + +=================== ===================== +Type Format specifier +=================== ===================== +bool %d, %x +char %d, %x +unsigned char %u, %x +short %d, %x +unsigned short %u, %x +int %d, %x +unsigned int %d, %x +long %ld, %lx +unsigned long %lu, %lx +long long %lld, %llx +unsigned long long %llu, %llx +off_t %llu, %llx +ptr_diff_t %td, %tx +fdt_addr_t %pa, see pointers +fdt_size_t %pa, see pointers +phys_addr_t %pa, see pointers +phys_size_t %pa, see pointers +size_t %zu, %zx, %Zu, %Zx +ssize_t %zd, %zx, %Zd, %Zx +=================== ===================== + +Characters +---------- + +%c + prints a single character + +Strings +------- + +%s + prints a UTF-8 string (char *) + +%ls + prints a UTF-16 string (u16 *) + +Pointers +-------- + +%p + prints the address the pointer points to hexadecimally + +%pa, %pap + prints the value of a phys_addr_t value that the pointer points to + preceded with 0x and zero padding according to size of phys_addr_t + +%pD + prints an UEFI device path + +%pi4, %pI4 + prints IPv4 address, e.g. '192.168.0.1' + +%pm + prints MAC address without separators, e.g. '001122334455' + +%pM + print MAC address colon separated, e.g. '00:01:02:03:04:05' + +%pUb + prints GUID big endian, lower case + e.g. '00112233-4455-6677-8899-aabbccddeeff' + +%pUB + prints GUID big endian, upper case + e.g. '00112233-4455-6677-8899-AABBCCDDEEFF' + +%pUl + prints GUID low endian, lower case + e.g. '33221100-5544-7766-8899-aabbccddeeff' + +%pUL + prints GUID low endian, upper case + e.g. '33221100-5544-7766-8899-AABBCCDDEEFF' + +%pUs + prints text description of a GUID or if such is not known low endian, + lower case, e.g. 'system' for a GUID identifying an EFI system + partition.