#include <machine/asmacros.h>

#include "assym.s"

	.text

/*
 * cpu_switch(old, new)
 *
 * Save the current thread state, then select the next thread to run
 * and load its state.
 * 0(%esp) = ret
 * 4(%esp) = oldtd
 * 8(%esp) = newtd
 */
ENTRY(cpu_kswitch)
	movl	4(%esp),%ecx			/* Old thread */
	movl	TD_PCB(%ecx),%edx		/* Old pcb */

	/* Save context. */
	movl	(%esp),%eax			/* Hardware registers */
	movl	%eax,PCB_EIP(%edx)
	movl	%ebx,PCB_EBX(%edx)
	movl	%esp,PCB_ESP(%edx)
	movl	%ebp,PCB_EBP(%edx)
	movl	%esi,PCB_ESI(%edx)
	movl	%edi,PCB_EDI(%edx)

	movl	8(%esp),%ecx			/* New thread */
	movl	TD_PCB(%ecx),%edx		/* New pcb */

	/* Restore context. */
	movl	PCB_EBX(%edx),%ebx
	movl	PCB_ESP(%edx),%esp
	movl	PCB_EBP(%edx),%ebp
	movl	PCB_ESI(%edx),%esi
	movl	PCB_EDI(%edx),%edi
	movl	PCB_EIP(%edx),%eax
	movl	%eax,(%esp)
	pushl	PCB_PSL(%edx)
	popfl

	movl	%edx, PCPU(CURPCB)
	movl	%ecx, PCPU(CURTHREAD)		/* into next thread */

	ret