1/* 2 Copyright Oliver Kowalke 2009. 3 Distributed under the Boost Software License, Version 1.0. 4 (See accompanying file LICENSE_1_0.txt or copy at 5 http://www.boost.org/LICENSE_1_0.txt) 6*/ 7 8/******************************************************* 9 * * 10 * ------------------------------------------------- * 11 * | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | * 12 * ------------------------------------------------- * 13 * | 0 | 4 | 8 | 12 | 16 | 20 | 24 | 28 | * 14 * ------------------------------------------------- * 15 * | R13 | R14 | R15 | R16 | * 16 * ------------------------------------------------- * 17 * ------------------------------------------------- * 18 * | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | * 19 * ------------------------------------------------- * 20 * | 32 | 36 | 40 | 44 | 48 | 52 | 56 | 60 | * 21 * ------------------------------------------------- * 22 * | R17 | R18 | R19 | R20 | * 23 * ------------------------------------------------- * 24 * ------------------------------------------------- * 25 * | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | * 26 * ------------------------------------------------- * 27 * | 64 | 68 | 72 | 76 | 80 | 84 | 88 | 92 | * 28 * ------------------------------------------------- * 29 * | R21 | R22 | R23 | R24 | * 30 * ------------------------------------------------- * 31 * ------------------------------------------------- * 32 * | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | * 33 * ------------------------------------------------- * 34 * | 96 | 100 | 104 | 108 | 112 | 116 | 120 | 124 | * 35 * ------------------------------------------------- * 36 * | R25 | R26 | R27 | R28 | * 37 * ------------------------------------------------- * 38 * ------------------------------------------------- * 39 * | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | * 40 * ------------------------------------------------- * 41 * | 128 | 132 | 136 | 140 | 144 | 148 | 152 | 156 | * 42 * ------------------------------------------------- * 43 * | R29 | R30 | R31 | hidden | * 44 * ------------------------------------------------- * 45 * ------------------------------------------------- * 46 * | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | * 47 * ------------------------------------------------- * 48 * | 160 | 164 | 168 | 172 | 176 | 180 | 184 | 188 | * 49 * ------------------------------------------------- * 50 * | CR | LR | PC | back-chain| * 51 * ------------------------------------------------- * 52 * ------------------------------------------------- * 53 * | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | * 54 * ------------------------------------------------- * 55 * | 192 | 196 | 200 | 204 | 208 | 212 | 216 | 220 | * 56 * ------------------------------------------------- * 57 * | cr saved | lr saved | compiler | linker | * 58 * ------------------------------------------------- * 59 * ------------------------------------------------- * 60 * | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | * 61 * ------------------------------------------------- * 62 * | 224 | 228 | 232 | 236 | 240 | 244 | 248 | 252 | * 63 * ------------------------------------------------- * 64 * | FCTX | DATA | | | * 65 * ------------------------------------------------- * 66 * * 67 *******************************************************/ 68 69.text 70.globl _make_fcontext 71_make_fcontext: 72 ; save return address into R6 73 mflr r6 74 75 ; first arg of make_fcontext() == top address of context-function 76 ; shift address in R3 to lower 16 byte boundary 77 clrrwi r3, r3, 4 78 79 ; reserve space for context-data on context-stack 80 ; including 64 byte of linkage + parameter area (R1 16 == 0) 81 subi r3, r3, 240 82 83 ; third arg of make_fcontext() == address of context-function 84 stw r5, 176(r3) 85 86 ; set back-chain to zero 87 li r0, 0 88 std r0, 184(r3) 89 90 ; compute address of returned transfer_t 91 addi r0, r3, 224 92 mr r4, r0 93 std r4, 152(r3) 94 95 ; load LR 96 mflr r0 97 ; jump to label 1 98 bl l1 99l1: 100 ; load LR into R4 101 mflr r4 102 ; compute abs address of label finish 103 addi r4, r4, lo16((finish - .) + 4) 104 ; restore LR 105 mtlr r0 106 ; save address of finish as return-address for context-function 107 ; will be entered after context-function returns 108 std r4, 168(r3) 109 110 ; restore return address from R6 111 mtlr r6 112 113 blr ; return pointer to context-data 114 115finish: 116 ; save return address into R0 117 mflr r0 118 ; save return address on stack, set up stack frame 119 stw r0, 8(r1) 120 ; allocate stack space, R1 16 == 0 121 stwu r1, -32(r1) 122 123 ; set return value to zero 124 li r3, 0 125 ; exit application 126 bl __exit 127 nop 128