| 1 | @ 32 bit ARM context switch |
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| 2 | @ This function assumes that r9 has no special meaning on the platform it's |
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| 3 | @ being built on. |
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| 4 | @ If r9 is special, uncomment the following line and it will be left alone |
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| 5 | |
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| 6 | @ #define R9_SPECIAL |
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| 7 | |
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| 8 | #define PTR_BYTE 4 |
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| 9 | #define SP_OFFSET ( 0 * PTR_BYTE ) |
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| 10 | #define FP_OFFSET ( 1 * PTR_BYTE ) |
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| 11 | #define PC_OFFSET ( 2 * PTR_BYTE ) |
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| 12 | |
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| 13 | .text |
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| 14 | .align 2 |
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| 15 | .global CtxSwitch |
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| 16 | .type CtxSwitch, %function |
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| 17 | |
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| 18 | CtxSwitch: |
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| 19 | @ save callee-saved registers: r4-r8, r10, r11, r13(sp) (plus r9 depending on platform specification) |
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| 20 | @ I've seen reference to 31 registers on 64-bit, if this is the case, more need to be saved |
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| 21 | @ save thread state registers: r14(lr) |
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| 22 | @ r12(ip) is intra-procedure-call scratch register, does not need saving between function calls |
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| 23 | |
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| 24 | #ifdef R9_SPECIAL |
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| 25 | stmfd r13!, {r4-r8,r10,r11,r14} |
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| 26 | #else |
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| 27 | stmfd r13!, {r4-r11,r14} |
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| 28 | #endif // R9_SPECIAL |
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| 29 | |
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| 30 | @ save floating point registers: s16-s31 |
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| 31 | vstmdb r13!, {s16-s31} |
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| 32 | |
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| 33 | @ save frame pointer and stack pointer to outgoing datastructure |
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| 34 | str sp, [r0, #SP_OFFSET] |
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| 35 | str fp, [r0, #FP_OFFSET] |
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| 36 | |
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| 37 | @ restore frame pointer and stack pointer from incoming datastructure |
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| 38 | ldr fp, [r1, #FP_OFFSET] |
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| 39 | ldr sp, [r1, #SP_OFFSET] |
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| 40 | |
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| 41 | @ restore floating point registers: s16-s31 |
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| 42 | vldm r13!, {s16-s31} |
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| 43 | @ restore r14(lr) |
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| 44 | @ restore 64-bit extra registers? |
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| 45 | @ restore callee-saved registers: r4-r8, r10, r11, r13 |
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| 46 | |
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| 47 | #ifdef R9_SPECIAL |
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| 48 | ldmfd r13!, {r4-r8,r10,r11,r15} |
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| 49 | #else |
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| 50 | ldmfd r13!, {r4-r11,r14} @ loading r14 back into r15 returns |
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| 51 | |
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| 52 | mov r15, r14 |
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| 53 | #endif // R9_SPECIAL |
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| 54 | |
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| 55 | .text |
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| 56 | .align 2 |
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| 57 | .global CtxInvokeStub |
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| 58 | .type CtxInvokeStub, %function |
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| 59 | |
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| 60 | CtxInvokeStub: |
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| 61 | ldmfd r13!, {r0-r1} |
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| 62 | mov r15, r1 |
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