From 74360f142c0d98a4f643f3417133bea0b7fca75e Mon Sep 17 00:00:00 2001 From: Georg-Johann Lay Date: Fri, 21 Jul 2017 08:20:51 +0000 Subject: [PATCH] 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 | 4 +++ gcc/doc/extend.texi | 77 ++++++++++++++++++++++++++--------------------------- 2 files changed, 42 insertions(+), 39 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 121af77..b024884 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,7 @@ +2017-07-21 Georg-Johann Lay + + * doc/invoke.texi (AVR Built-in Functions): Re-layout section. + 2016-07-21 Jan Hubicka * cfgcleanup.c (flow_find_cross_jump): Do not crossjump across diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index b6244a0..da5b0af 100644 --- a/gcc/doc/extend.texi +++ b/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 + +// 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 -- 2.7.4