sysdep.h

glibc 库, 不仅可以学习使用库函数,还可以学习函数的具体实现,是提高功力的好资料

/* Assembly macros for 32-bit PowerPC.
   Copyright (C) 1999, 2001, 2002, 2003, 2006 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA
   02110-1301 USA.  */

#include <sysdeps/powerpc/sysdep.h>

#ifdef __ASSEMBLER__

#ifdef __ELF__

/* If compiled for profiling, call `_mcount' at the start of each
   function.  */
#ifdef	PROF
/* The mcount code relies on a the return address being on the stack
   to locate our caller and so it can restore it; so store one just
   for its benefit.  */
# define CALL_MCOUNT							      \
  mflr  r0;								      \
  stw   r0,4(r1);							      \
  cfi_offset (lr, 4);	       						      \
  bl    JUMPTARGET(_mcount);
#else  /* PROF */
# define CALL_MCOUNT		/* Do nothing.  */
#endif /* PROF */

#define	ENTRY(name)							      \
  ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME(name);				      \
  ASM_TYPE_DIRECTIVE (C_SYMBOL_NAME(name),@function)			      \
  .align ALIGNARG(2);							      \
  C_LABEL(name)								      \
  cfi_startproc;							      \
  CALL_MCOUNT

#define EALIGN_W_0  /* No words to insert.  */
#define EALIGN_W_1  nop
#define EALIGN_W_2  nop;nop
#define EALIGN_W_3  nop;nop;nop
#define EALIGN_W_4  EALIGN_W_3;nop
#define EALIGN_W_5  EALIGN_W_4;nop
#define EALIGN_W_6  EALIGN_W_5;nop
#define EALIGN_W_7  EALIGN_W_6;nop

/* EALIGN is like ENTRY, but does alignment to 'words'*4 bytes
   past a 2^align boundary.  */
#ifdef PROF
# define EALIGN(name, alignt, words)					      \
  ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME(name);				      \
  ASM_TYPE_DIRECTIVE (C_SYMBOL_NAME(name),@function)			      \
  .align ALIGNARG(2);							      \
  C_LABEL(name)								      \
  cfi_startproc;							      \
  CALL_MCOUNT								      \
  b 0f;									      \
  .align ALIGNARG(alignt);						      \
  EALIGN_W_##words;							      \
  0:
#else /* PROF */
# define EALIGN(name, alignt, words)					      \
  ASM_GLOBAL_DIRECTIVE C_SYMBOL_NAME(name);				      \
  ASM_TYPE_DIRECTIVE (C_SYMBOL_NAME(name),@function)			      \
  .align ALIGNARG(alignt);						      \
  EALIGN_W_##words;							      \
  C_LABEL(name)								      \
  cfi_startproc;
#endif

#undef	END
#define END(name)							      \
  cfi_endproc;								      \
  ASM_SIZE_DIRECTIVE(name)

#define DO_CALL(syscall)				      		      \
    li 0,syscall;						              \
    sc

#undef JUMPTARGET
#ifdef PIC
# define JUMPTARGET(name) name##@plt
#else
# define JUMPTARGET(name) name
#endif

#if defined SHARED && defined DO_VERSIONING && defined PIC \
    && !defined NO_HIDDEN
# undef HIDDEN_JUMPTARGET
# define HIDDEN_JUMPTARGET(name) __GI_##name##@local
#endif

#define PSEUDO(name, syscall_name, args)				      \
  .section ".text";							      \
  ENTRY (name)								      \
    DO_CALL (SYS_ify (syscall_name));

#define PSEUDO_RET							      \
    bnslr+;								      \
    b __syscall_error@local
#define ret PSEUDO_RET

#undef	PSEUDO_END
#define	PSEUDO_END(name)						      \
  END (name)

#define PSEUDO_NOERRNO(name, syscall_name, args)			      \
  .section ".text";							      \
  ENTRY (name)								      \
    DO_CALL (SYS_ify (syscall_name));

#define PSEUDO_RET_NOERRNO						      \
    blr
#define ret_NOERRNO PSEUDO_RET_NOERRNO

#undef	PSEUDO_END_NOERRNO
#define	PSEUDO_END_NOERRNO(name)					      \
  END (name)

#define PSEUDO_ERRVAL(name, syscall_name, args)				      \
  .section ".text";							      \
  ENTRY (name)								      \
    DO_CALL (SYS_ify (syscall_name));

#define PSEUDO_RET_ERRVAL						      \
    blr
#define ret_ERRVAL PSEUDO_RET_ERRVAL

#undef	PSEUDO_END_ERRVAL
#define	PSEUDO_END_ERRVAL(name)						      \
  END (name)

/* Local labels stripped out by the linker.  */
#undef L
#define L(x) .L##x

/* Label in text section.  */
#define C_TEXT(name) name

#endif /* __ELF__ */

#endif	/* __ASSEMBLER__ */