Document the format specifier codes used by U-Boot's printf()
implementation.
Signed-off-by: Heinrich Schuchardt <heinrich.schucha...@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.
--
2.33.1
