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lampret |
/* This is a simple version of setjmp and longjmp.
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Nick Clifton, Cygnus Solutions, 13 June 1997. */
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.text
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.code 32
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.align 2
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/* int setjmp (jmp_buf); */
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.globl _setjmp
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_setjmp:
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/* Save all the callee-preserved registers into the jump buffer. */
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stmea a1!, { v1-v7, fp, ip, sp, lr }
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#if 0 /* Simulator does not cope with FP instructions yet.... */
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#ifndef __SOFTFP__
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/* Save the floating point registers */
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sfmea f4, 4, [a1]
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#endif
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#endif
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/* When setting up the jump buffer return 0. */
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mov a1, #0
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/* Return to caller, see comment in longjmp below */
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#ifdef __APCS_26__
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movs pc, lr
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#else
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tst lr, #1
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moveq pc, lr
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.word 0xe12fff1e /* bx lr */
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#endif
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/* volatile void longjmp (jmp_buf, int); */
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.globl _longjmp
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_longjmp:
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/* If we have stack extension code it ought to be handled here. */
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/* Restore the registers, retrieving the state when setjmp() was called. */
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ldmfd a1!, { v1-v7, fp, ip, sp, lr }
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#if 0 /* Simulator does not cope with FP instructions yet.... */
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#ifndef __SOFTFP__
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/* Restore floating point registers as well */
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lfmfd f4, 4, [a1]
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#endif
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#endif
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/* Put the return value into the integer result register.
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But if it is zero then return 1 instead. */
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movs a1, a2
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moveq a1, #1
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/* Arm/Thumb interworking support:
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The interworking scheme expects functions to use a BX instruction
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to return control to their parent. Since we need this code to work
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in both interworked and non-interworked environments as well as with
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older processors which do not have the BX instruction we do the
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following:
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Test the return address.
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If the bottom bit is clear perform an "old style" function exit.
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(We know that we are in ARM mode and returning to an ARM mode caller).
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Otherwise use the BX instruction to perform the function exit.
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We know that we will never attempt to perform the BX instruction on
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an older processor, because that kind of processor will never be
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interworked, and a return address with the bottom bit set will never
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be generated.
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In addition, we do not actually assemble the BX instruction as this would
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require us to tell the assembler that the processor is an ARM7TDMI and
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it would store this information in the binary. We want this binary to be
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able to be linked with binaries compiled for older processors however, so
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we do not want such information stored there.
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If we are running using the APCS-26 convention however, then we never
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test the bottom bit, because this is part of the processor status.
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Instead we just do a normal return, since we know that we cannot be
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returning to a Thumb caller - the Thumb doe snot support APCS-26
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*/
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#ifdef __APCS_26__
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movs pc, lr
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#else
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tst lr, #1
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moveq pc, lr
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.word 0xe12fff1e /* bx lr */
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#endif
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