| 1 | /* This is a simple version of setjmp and longjmp. |
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| 2 | |
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| 3 | Nick Clifton, Cygnus Solutions, 13 June 1997. */ |
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| 4 | |
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| 5 | /* ANSI concatenation macros. */ |
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| 6 | #define CONCAT(a, b) CONCAT2(a, b) |
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| 7 | #define CONCAT2(a, b) a##b |
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| 8 | |
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| 9 | #ifndef __USER_LABEL_PREFIX__ |
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| 10 | #error __USER_LABEL_PREFIX__ not defined |
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| 11 | #endif |
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| 12 | |
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| 13 | #define SYM(x) CONCAT (__USER_LABEL_PREFIX__, x) |
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| 14 | |
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| 15 | #ifdef __ELF__ |
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| 16 | #define TYPE(x) .type SYM(x),function |
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| 17 | #define SIZE(x) .size SYM(x), . - SYM(x) |
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| 18 | #else |
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| 19 | #define TYPE(x) |
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| 20 | #define SIZE(x) |
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| 21 | #endif |
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| 22 | |
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| 23 | /* Arm/Thumb interworking support: |
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| 24 | |
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| 25 | The interworking scheme expects functions to use a BX instruction |
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| 26 | to return control to their parent. Since we need this code to work |
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| 27 | in both interworked and non-interworked environments as well as with |
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| 28 | older processors which do not have the BX instruction we do the |
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| 29 | following: |
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| 30 | Test the return address. |
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| 31 | If the bottom bit is clear perform an "old style" function exit. |
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| 32 | (We know that we are in ARM mode and returning to an ARM mode caller). |
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| 33 | Otherwise use the BX instruction to perform the function exit. |
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| 34 | |
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| 35 | We know that we will never attempt to perform the BX instruction on |
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| 36 | an older processor, because that kind of processor will never be |
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| 37 | interworked, and a return address with the bottom bit set will never |
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| 38 | be generated. |
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| 39 | |
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| 40 | In addition, we do not actually assemble the BX instruction as this would |
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| 41 | require us to tell the assembler that the processor is an ARM7TDMI and |
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| 42 | it would store this information in the binary. We want this binary to be |
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| 43 | able to be linked with binaries compiled for older processors however, so |
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| 44 | we do not want such information stored there. |
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| 45 | |
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| 46 | If we are running using the APCS-26 convention however, then we never |
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| 47 | test the bottom bit, because this is part of the processor status. |
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| 48 | Instead we just do a normal return, since we know that we cannot be |
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| 49 | returning to a Thumb caller - the Thumb does not support APCS-26. |
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| 50 | |
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| 51 | Function entry is much simpler. If we are compiling for the Thumb we |
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| 52 | just switch into ARM mode and then drop through into the rest of the |
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| 53 | function. The function exit code will take care of the restore to |
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| 54 | Thumb mode. */ |
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| 55 | |
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| 56 | #ifdef __APCS_26__ |
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| 57 | #define RET movs pc, lr |
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| 58 | #else |
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| 59 | #define RET tst lr, #1; \ |
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| 60 | moveq pc, lr ; \ |
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| 61 | .word 0xe12fff1e /* bx lr */ |
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| 62 | #endif |
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| 63 | |
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| 64 | #ifdef __thumb__ |
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| 65 | #define MODE .thumb_func |
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| 66 | .macro PROLOGUE name |
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| 67 | .code 16 |
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| 68 | bx pc |
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| 69 | nop |
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| 70 | .code 32 |
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| 71 | SYM (.arm_start_of.\name): |
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| 72 | .endm |
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| 73 | #else |
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| 74 | #define MODE .code 32 |
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| 75 | .macro PROLOGUE name |
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| 76 | .endm |
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| 77 | #endif |
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| 78 | |
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| 79 | .macro FUNC_START name |
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| 80 | .text |
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| 81 | .align 2 |
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| 82 | MODE |
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| 83 | .globl SYM (\name) |
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| 84 | TYPE (\name) |
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| 85 | SYM (\name): |
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| 86 | PROLOGUE \name |
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| 87 | .endm |
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| 88 | |
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| 89 | .macro FUNC_END name |
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| 90 | RET |
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| 91 | SIZE (\name) |
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| 92 | .endm |
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| 93 | |
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| 94 | /* -------------------------------------------------------------------- |
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| 95 | int setjmp (jmp_buf); |
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| 96 | -------------------------------------------------------------------- */ |
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| 97 | |
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| 98 | FUNC_START setjmp |
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| 99 | |
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| 100 | /* Save all the callee-preserved registers into the jump buffer. */ |
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| 101 | stmea a1!, { v1-v7, fp, ip, sp, lr } |
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| 102 | |
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| 103 | #if 0 /* Simulator does not cope with FP instructions yet. */ |
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| 104 | #ifndef __SOFTFP__ |
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| 105 | /* Save the floating point registers. */ |
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| 106 | sfmea f4, 4, [a1] |
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| 107 | #endif |
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| 108 | #endif |
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| 109 | /* When setting up the jump buffer return 0. */ |
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| 110 | mov a1, #0 |
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| 111 | |
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| 112 | FUNC_END setjmp |
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| 113 | |
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| 114 | /* -------------------------------------------------------------------- |
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| 115 | volatile void longjmp (jmp_buf, int); |
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| 116 | -------------------------------------------------------------------- */ |
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| 117 | |
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| 118 | FUNC_START longjmp |
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| 119 | |
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| 120 | /* If we have stack extension code it ought to be handled here. */ |
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| 121 | |
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| 122 | /* Restore the registers, retrieving the state when setjmp() was called. */ |
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| 123 | ldmfd a1!, { v1-v7, fp, ip, sp, lr } |
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| 124 | |
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| 125 | #if 0 /* Simulator does not cope with FP instructions yet. */ |
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| 126 | #ifndef __SOFTFP__ |
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| 127 | /* Restore floating point registers as well. */ |
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| 128 | lfmfd f4, 4, [a1] |
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| 129 | #endif |
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| 130 | #endif |
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| 131 | /* Put the return value into the integer result register. |
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| 132 | But if it is zero then return 1 instead. */ |
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| 133 | movs a1, a2 |
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| 134 | moveq a1, #1 |
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| 135 | |
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| 136 | FUNC_END longjmp |
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| 137 | |
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