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/*
* Allocates a C string on the stack, for
* use within system calls, which is the only
* place the Myrddin stack should need nul-terminated
* strings.
*
* This is in assembly, because for efficiency we
* allocate the C strings on the stack, and don't adjust
* SP when returning.
*/
TEXT sys$cstring+0(SB),$0
/* save registers */
MOVQ SP,AX
SUBQ $40,SP
MOVQ BP,-8(AX)
MOVQ R15,-16(AX)
MOVQ SI,-24(AX)
MOVQ DI,-32(AX)
MOVQ CX,-40(AX)
MOVQ AX,BP
MOVQ (BP),R15 /* ret addr */
MOVQ 8(BP),SI /* src */
MOVQ 16(BP),CX /* len */
SUBQ CX,SP /* get stack */
SUBQ $1,SP /* +1 for nul */
MOVQ SP,DI /* dest */
MOVQ SP,AX /* ret val */
ANDQ $(~15),SP /* align */
SUBQ $32,SP /* "unpop" the args and make room for return addr */
CLD
REP
MOVSB
MOVB $0,(DI) /* terminate */
/* Restore registers */
MOVQ R15,0(SP) /* place ret addr */
MOVQ -40(BP),CX
MOVQ -32(BP),DI
MOVQ -24(BP),SI
MOVQ -16(BP),R15
MOVQ -8(BP) ,BP
RET
TEXT sys$alloca+0(SB),$0
/* save registers */
MOVQ (SP),R10 /* ret addr */
/* get stack space */
SUBQ DI,SP /* get stack space */
MOVQ SP,AX /* top of stack (return value) */
ANDQ $(~15),SP /* align */
SUBQ $32,SP /* "unpop" the args, and make room for ret addr */
MOVQ R10,(SP) /* place ret addr */
RET
GLOBL sys$curbrk+0(SB),$8
DATA sys$curbrk+0(SB)/8,$end+0(SB)
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