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 180