source: mainline/arch/ia32/src/context.s@ d47f0e1

#
# Copyright (C) 2001-2004 Jakub Jermar
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.text

.global context_save
.global context_restore


## Save current CPU context
#
# Save CPU context to the kernel_context variable
# pointed by the 1st argument. Returns 1 in EAX.
#
context_save:
        push %ebx

        movl 4(%esp),%eax       # the caller's return %eip
        movl 8(%esp),%ebx       # address of the kernel_context variable to save context to
        movl %eax,4(%ebx)       # %eip -> ctx->pc
        movl %esp,(%ebx)        # %esp -> ctx->sp

        movl %ebx,%eax
        pop %ebx

        movl %ebx,8(%eax)
        movl %ecx,12(%eax)
        movl %edx,16(%eax)
        movl %esi,20(%eax)
        movl %edi,24(%eax)
        movl %ebp,28(%eax)    
    
        xorl %eax,%eax          # context_save returns 1
        incl %eax
        ret


## Restore current CPU context
#
# Restore CPU context from the kernel_context variable
# pointed by the 1st argument. Returns 0 in EAX.
#    
context_restore:
        movl 4(%esp),%eax       # address of the kernel_context variable to restore context from
        movl (%eax),%esp        # ctx->sp -> %esp
        addl $4,%esp            # this is for the pop we don't do

        movl 8(%eax),%ebx
        movl 12(%eax),%ecx
        movl 16(%eax),%edx
        movl 20(%eax),%esi
        movl 24(%eax),%edi
        movl 28(%eax),%ebp

        movl 4(%eax),%eax
        movl %eax,(%esp)        # ctx->pc -> saver's return %eip
        xorl %eax,%eax          # context_restore returns 0
        ret