github.com/prattmic/llgo-embedded@v0.0.0-20150820070356-41cfecea0e1e/third_party/gofrontend/libffi/src/bfin/sysv.S (about)

     1  /* -----------------------------------------------------------------------
     2     sysv.S - Copyright (c) 2012  Alexandre K. I. de Mendonca <alexandre.keunecke@gmail.com>,
     3                                  Paulo Pizarro <paulo.pizarro@gmail.com>
     4  
     5     Blackfin Foreign Function Interface
     6  
     7     Permission is hereby granted, free of charge, to any person obtaining
     8     a copy of this software and associated documentation files (the
     9     ``Software''), to deal in the Software without restriction, including
    10     without limitation the rights to use, copy, modify, merge, publish,
    11     distribute, sublicense, and/or sell copies of the Software, and to
    12     permit persons to whom the Software is furnished to do so, subject to
    13     the following conditions:
    14  
    15     The above copyright notice and this permission notice shall be included
    16     in all copies or substantial portions of the Software.
    17  
    18     THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND,
    19     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    20     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    21     NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    22     HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
    23     WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    24     OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    25     DEALINGS IN THE SOFTWARE.
    26     ----------------------------------------------------------------------- */
    27  
    28  #define LIBFFI_ASM
    29  #include <fficonfig.h>
    30  #include <ffi.h>
    31  
    32  .text
    33  .align 4
    34  
    35  	/*
    36  	 There is a "feature" in the bfin toolchain that it puts a _ before function names
    37  	 that's why the function here it's called _ffi_call_SYSV and not ffi_call_SYSV
    38  	 */
    39  	.global _ffi_call_SYSV;
    40  	.type _ffi_call_SYSV, STT_FUNC;
    41  	.func ffi_call_SYSV
    42  
    43  	/*
    44           cif->bytes    = R0    (fp+8)
    45           &ecif         = R1    (fp+12)
    46           ffi_prep_args = R2    (fp+16)
    47           ret_type      = stack (fp+20)
    48           ecif.rvalue   = stack (fp+24)
    49           fn            = stack (fp+28)
    50                             got (fp+32)
    51  
    52          There is room for improvement here (we can use temporary registers
    53          instead of saving the values in the memory)
    54          REGS:
    55          P5 => Stack pointer (function arguments)
    56          R5 => cif->bytes
    57          R4 => ret->type
    58  
    59          FP-20 = P3
    60          FP-16 = SP (parameters area)
    61          FP-12 = SP (temp)
    62          FP-08 = function return part 1 [R0]
    63          FP-04 = function return part 2 [R1]
    64  	*/
    65  
    66  _ffi_call_SYSV:
    67  .prologue:
    68  	LINK 20;
    69  	[FP-20] = P3;
    70  	[FP+8] = R0;
    71  	[FP+12] = R1;
    72  	[FP+16] = R2;
    73  
    74  .allocate_stack:
    75  	//alocate cif->bytes into the stack
    76  	R1 = [FP+8];
    77  	R0 = SP;
    78  	R0 = R0 - R1;
    79  	R1 = 4;
    80  	R0 = R0 - R1;
    81  	[FP-12] = SP;
    82  	SP = R0;
    83  	[FP-16] = SP;
    84  
    85  .call_prep_args:
    86  	//get the addr of prep_args
    87  	P0 = [P3 + _ffi_prep_args@FUNCDESC_GOT17M4];
    88  	P1 = [P0];
    89  	P3 = [P0+4];
    90  	R0 = [FP-16];//SP (parameter area)
    91  	R1 = [FP+12];//ecif
    92  	call (P1);
    93  
    94  .call_user_function:
    95  	//ajust SP so as to allow the user function access the parameters on the stack
    96  	SP = [FP-16]; //point to function parameters
    97  	R0 = [SP];
    98  	R1 = [SP+4];
    99  	R2 = [SP+8];
   100  	//load user function address
   101  	P0 = FP;
   102  	P0 +=28;
   103  	P1 = [P0];
   104  	P1 = [P1];
   105  	P3 = [P0+4];
   106  	/*
   107  		For functions returning aggregate values (struct) occupying more than 8 bytes,
   108  		the caller allocates the return value object on the stack and the address
   109  		of this object is passed to the callee as a hidden argument in register P0.
   110  	*/
   111  	P0 = [FP+24];
   112  
   113  	call (P1);
   114  	SP = [FP-12];
   115  .compute_return:
   116  	P2 = [FP-20];
   117  	[FP-8] = R0;
   118  	[FP-4] = R1;
   119  
   120  	R0 = [FP+20];
   121  	R1 = R0 << 2;
   122  
   123  	R0 = [P2+.rettable@GOT17M4];
   124  	R0 = R1 + R0;
   125  	P2 = R0;
   126  	R1 = [P2];
   127  
   128  	P2 = [FP+-20];
   129  	R0 = [P2+.rettable@GOT17M4];
   130  	R0 = R1 + R0;
   131  	P2 = R0;
   132  	R0 = [FP-8];
   133  	R1 = [FP-4];
   134  	jump (P2);
   135  
   136  /*
   137  #define FFIBFIN_RET_VOID 0
   138  #define FFIBFIN_RET_BYTE 1
   139  #define FFIBFIN_RET_HALFWORD 2
   140  #define FFIBFIN_RET_INT64 3
   141  #define FFIBFIN_RET_INT32 4
   142  */
   143  .align 4
   144  .align 4
   145  .rettable:
   146  	.dd .epilogue - .rettable
   147  	.dd	.rbyte - .rettable;
   148  	.dd	.rhalfword - .rettable;
   149  	.dd	.rint64 - .rettable;
   150  	.dd	.rint32 - .rettable;
   151  
   152  .rbyte:
   153  	P0 = [FP+24];
   154  	R0 = R0.B (Z);
   155  	[P0] = R0;
   156  	JUMP .epilogue
   157  .rhalfword:
   158  	P0 = [FP+24];
   159  	R0 = R0.L;
   160  	[P0] = R0;
   161  	JUMP .epilogue
   162  .rint64:
   163  	P0 = [FP+24];// &rvalue
   164  	[P0] = R0;
   165  	[P0+4] = R1;
   166  	JUMP .epilogue
   167  .rint32:
   168  	P0 = [FP+24];
   169  	[P0] = R0;
   170  .epilogue:
   171  	R0 = [FP+8];
   172  	R1 = [FP+12];
   173  	R2 = [FP+16];
   174  	P3 = [FP-20];
   175  	UNLINK;
   176  	RTS;
   177  
   178  .size _ffi_call_SYSV,.-_ffi_call_SYSV;
   179  .endfunc