| 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 __cfactx_switch
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| 16 | .type __cfactx_switch, %function
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| 17 |
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| 18 | __cfactx_switch:
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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 __cfactx_invoke_stub
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| 58 | .type __cfactx_invoke_stub, %function
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| 59 |
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| 60 | __cfactx_invoke_stub:
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| 61 | ldmfd r13!, {r0-r1}
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| 62 | mov r15, r1
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