invoke.texi (AVR Built-in Functions): Re-layout section.

gcc/
	* doc/invoke.texi (AVR Built-in Functions): Re-layout section.

From-SVN: r250419

gcc/ChangeLog

+2017-07-21  Georg-Johann Lay  <avr@gjlay.de>
+
+	* doc/invoke.texi (AVR Built-in Functions): Re-layout section.
+
 2016-07-21  Jan Hubicka  <hubicka@ucw.cz>
 
 	* cfgcleanup.c (flow_find_cross_jump): Do not crossjump across

gcc/doc/extend.texi

@@ -12748,54 +12748,37 @@ or if not a specific built-in is implemented or not. For example, if
 @code{__builtin_avr_nop} is available the macro
 @code{__BUILTIN_AVR_NOP} is defined to @code{1} and undefined otherwise.
 
-The following built-in functions map to the respective machine
+@table @code
+
+@item void __builtin_avr_nop (void)
+@itemx void __builtin_avr_sei (void)
+@itemx void __builtin_avr_cli (void)
+@itemx void __builtin_avr_sleep (void)
+@itemx void __builtin_avr_wdr (void)
+@itemx unsigned char __builtin_avr_swap (unsigned char)
+@itemx unsigned int __builtin_avr_fmul (unsigned char, unsigned char)
+@itemx int __builtin_avr_fmuls (char, char)
+@itemx int __builtin_avr_fmulsu (char, unsigned char)
+These built-in functions map to the respective machine
 instruction, i.e.@: @code{nop}, @code{sei}, @code{cli}, @code{sleep},
 @code{wdr}, @code{swap}, @code{fmul}, @code{fmuls}
 resp. @code{fmulsu}. The three @code{fmul*} built-ins are implemented
 as library call if no hardware multiplier is available.
 
-@smallexample
-void __builtin_avr_nop (void)
-void __builtin_avr_sei (void)
-void __builtin_avr_cli (void)
-void __builtin_avr_sleep (void)
-void __builtin_avr_wdr (void)
-unsigned char __builtin_avr_swap (unsigned char)
-unsigned int __builtin_avr_fmul (unsigned char, unsigned char)
-int __builtin_avr_fmuls (char, char)
-int __builtin_avr_fmulsu (char, unsigned char)
-@end smallexample
-
-In order to delay execution for a specific number of cycles, GCC
-implements
-@smallexample
-void __builtin_avr_delay_cycles (unsigned long ticks)
-@end smallexample
-
-@noindent
-@code{ticks} is the number of ticks to delay execution. Note that this
+@item void __builtin_avr_delay_cycles (unsigned long ticks)
+Delay execution for @var{ticks} cycles. Note that this
 built-in does not take into account the effect of interrupts that
-might increase delay time. @code{ticks} must be a compile-time
+might increase delay time. @var{ticks} must be a compile-time
 integer constant; delays with a variable number of cycles are not supported.
 
-@smallexample
-char __builtin_avr_flash_segment (const __memx void*)
-@end smallexample
-
-@noindent
+@item char __builtin_avr_flash_segment (const __memx void*)
 This built-in takes a byte address to the 24-bit
 @ref{AVR Named Address Spaces,address space} @code{__memx} and returns
 the number of the flash segment (the 64 KiB chunk) where the address
 points to.  Counting starts at @code{0}.
 If the address does not point to flash memory, return @code{-1}.
 
-@smallexample
-unsigned char __builtin_avr_insert_bits (unsigned long map,
-                                         unsigned char bits,
-                                         unsigned char val)
-@end smallexample
-
-@noindent
+@item uint8_t __builtin_avr_insert_bits (uint32_t map, uint8_t bits, uint8_t val)
 Insert bits from @var{bits} into @var{val} and return the resulting
 value. The nibbles of @var{map} determine how the insertion is
 performed: Let @var{X} be the @var{n}-th nibble of @var{map}
@@ -12840,13 +12823,29 @@ __builtin_avr_insert_bits (0xffff3210, bits, val)
 __builtin_avr_insert_bits (0x01234567, bits, 0)
 @end smallexample
 
-@smallexample
-void __builtin_avr_nops (unsigned count)
-@end smallexample
+@item void __builtin_avr_nops (unsigned count)
+Insert @var{count} @code{NOP} instructions.
+The number of instructions must be a compile-time integer constant.
+
+@end table
 
 @noindent
-Insert @code{count} @code{NOP} instructions.
-The number of instructions must be a compile-time integer constant.
+There are many more AVR-specific built-in functions that are used to
+implement the ISO/IEC TR 18037 ``Embedded C'' fixed-point functions of
+section 7.18a.6.  You don't need to use these built-ins directly.
+Instead, use the declarations as supplied by the @code{stdfix.h} header
+with GNU-C99:
+
+@smallexample
+#include <stdfix.h>
+
+// Re-interpret the bit representation of unsigned 16-bit
+// integer @var{uval} as Q-format 0.16 value.
+unsigned fract get_bits (uint_ur_t uval)
+@{
+    return urbits (uval);
+@}
+@end smallexample
 
 @node Blackfin Built-in Functions
 @subsection Blackfin Built-in Functions