minix/lib/libc/arch/i386/misc/alloca.S

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/* */
/* alloca() - allocate space on the stack Author: Kees J. Bot */
/* 2 Dec 1993 */
.text
.balign 16
.globl _alloca
_alloca:
#if __ACK__
pop %ecx /* Return address */
pop %eax /* Bytes to allocate */
addl $2*4+3, %eax /* Add space for two saved register variables */
andb $0xFC, %al /* Align */
movl %esp, %ebx /* Keep current esp */
subl %eax, %esp /* Lower stack */
movl %esp, %eax /* Return value */
push 4(%ebx) /* Push what is probably the saved esi */
push (%ebx) /* Saved edi */
/* Now ACK can still do: */
/* pop edi; pop esi; leave; ret */
push %eax /* Dummy argument */
jmp *%ecx
#else
pop %ecx /* Return address */
pop %eax /* Bytes to allocate */
addl $3, %eax
andb $0xFC, %al /* Align */
subl %eax, %esp /* Lower stack */
movl %esp, %eax /* Return value */
push %eax /* Dummy argument */
jmp *%ecx
#endif