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1 /* Low-level libffi support for Altera Nios II.
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2
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3 Copyright (c) 2013 Mentor Graphics.
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4
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5 Permission is hereby granted, free of charge, to any person obtaining
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6 a copy of this software and associated documentation files (the
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7 ``Software''), to deal in the Software without restriction, including
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8 without limitation the rights to use, copy, modify, merge, publish,
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9 distribute, sublicense, and/or sell copies of the Software, and to
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10 permit persons to whom the Software is furnished to do so, subject to
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11 the following conditions:
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12
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13 The above copyright notice and this permission notice shall be
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14 included in all copies or substantial portions of the Software.
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15
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16 THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND,
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17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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19 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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20 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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21 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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22 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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23
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24 /* This function is declared on the C side as
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25
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26 extern UINT64 ffi_call_sysv (void (*arghook) (char *, extended_cif *),
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27 extended_cif *ecif,
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28 unsigned nbytes,
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29 void (*fn) (void));
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30
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31 On input, the arguments appear as
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32 r4 = arghook
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33 r5 = ecif
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34 r6 = nbytes
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35 r7 = fn
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36 */
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37
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38 .section .text
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39 .align 2
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40 .global ffi_call_sysv
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41 .type ffi_call_sysv, @function
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42
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43 ffi_call_sysv:
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44 .cfi_startproc
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45
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46 /* Create the stack frame, saving r16 so we can use it locally. */
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47 addi sp, sp, -12
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48 .cfi_def_cfa_offset 12
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49 stw ra, 8(sp)
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50 stw fp, 4(sp)
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51 stw r16, 0(sp)
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52 .cfi_offset 31, -4
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53 .cfi_offset 28, -8
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54 .cfi_offset 16, -12
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55 mov fp, sp
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56 .cfi_def_cfa_register 28
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57 mov r16, r7
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58
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59 /* Adjust the stack pointer to create the argument buffer
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60 nbytes long. */
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61 sub sp, sp, r6
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62
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63 /* Call the arghook function. */
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64 mov r2, r4 /* fn */
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65 mov r4, sp /* argbuffer */
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66 callr r2 /* r5 already contains ecif */
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67
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68 /* Pop off the first 16 bytes of the argument buffer on the stack,
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69 transferring the contents to the argument registers. */
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70 ldw r4, 0(sp)
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71 ldw r5, 4(sp)
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72 ldw r6, 8(sp)
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73 ldw r7, 12(sp)
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74 addi sp, sp, 16
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75
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76 /* Call the user function, which leaves its result in r2 and r3. */
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77 callr r16
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78
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79 /* Pop off the stack frame. */
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80 mov sp, fp
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81 ldw ra, 8(sp)
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82 ldw fp, 4(sp)
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83 ldw r16, 0(sp)
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84 addi sp, sp, 12
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85 ret
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86 .cfi_endproc
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87 .size ffi_call_sysv, .-ffi_call_sysv
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88
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89
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90 /* Closure trampolines jump here after putting the C helper address
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91 in r9 and the closure pointer in r10. The user-supplied arguments
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92 to the closure are in the normal places, in r4-r7 and on the
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93 stack. Push the register arguments on the stack too and then call the
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94 C helper function to deal with them. */
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95
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96 .section .text
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97 .align 2
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98 .global ffi_closure_sysv
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99 .type ffi_closure_sysv, @function
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100
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101 ffi_closure_sysv:
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102 .cfi_startproc
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103
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104 /* Create the stack frame, pushing the register args on the stack
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105 just below the stack args. This is the same trick illustrated
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106 in Figure 7-3 in the Nios II Processor Reference Handbook, used
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107 for variable arguments and structures passed by value. */
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108 addi sp, sp, -20
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109 .cfi_def_cfa_offset 20
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110 stw ra, 0(sp)
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111 .cfi_offset 31, -20
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112 stw r4, 4(sp)
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113 .cfi_offset 4, -16
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114 stw r5, 8(sp)
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115 .cfi_offset 5, -12
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116 stw r6, 12(sp)
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117 .cfi_offset 6, -8
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118 stw r7, 16(sp)
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119 .cfi_offset 7, -4
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120
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121 /* Call the helper.
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122 r4 = pointer to arguments on stack
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123 r5 = closure pointer (loaded in r10 by the trampoline)
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124 r9 = address of helper function (loaded by trampoline) */
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125 addi r4, sp, 4
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126 mov r5, r10
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127 callr r9
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128
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129 /* Pop the stack and return. */
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130 ldw ra, 0(sp)
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131 addi sp, sp, 20
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132 .cfi_def_cfa_offset -20
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133 ret
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134 .cfi_endproc
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135 .size ffi_closure_sysv, .-ffi_closure_sysv
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136
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