--- /dev/null
+/* Copyright (C) 1994 Free Software Foundation, Inc.
+ Contributed by Joel Sherrill (jsherril@redstone-emh2.army.mil),
+ On-Line Applications Research Corporation.
+
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+/* entry.s
+ *
+ * This file contains the entry point for the application.
+ * The name of this entry point is compiler dependent.
+ * It jumps to the BSP which is responsible for performing
+ * all initialization.
+ *
+ */
+
+ .data
+ .global _Do_Load_IDT
+ .global _Do_Load_GDT
+
+ .text
+ .global start # GNU default entry point
+ .global _establish_stack
+
+ .global _bsp_start
+ .global _load_segments
+ .global __exit
+
+start:
+ nop
+ cli # DISABLE INTERRUPTS!!!
+#
+# Load the segment registers
+#
+# NOTE: Upon return, gs will contain the segment descriptor for
+# a segment which maps directly to all of physical memory.
+#
+ jmp _load_segments # load board dependent segments
+
+#
+# Set up the stack
+#
+
+_establish_stack:
+
+ movl $stack_end,%esp # set stack pointer
+ movl $stack_end,%ebp # set base pointer
+
+#
+# Zero out the BSS segment
+#
+zero_bss:
+ cld # make direction flag count up
+ movl $_end,%ecx # find end of .bss
+ movl $_bss_start,%edi # edi = beginning of .bss
+ subl %edi,%ecx # ecx = size of .bss in bytes
+ shrl $2,%ecx # size of .bss in longs
+ xorl %eax,%eax # value to clear out memory
+ repne # while ecx != 0
+ stosl # clear a long in the bss
+
+#
+# Set the C heap information for malloc
+#
+ movl $heap_size,___C_heap_size # set ___C_heap_size
+ movl $heap_memory,___C_heap_start # set ___C_heap_start
+
+#
+# Copy the Global Descriptor Table to our space
+#
+
+ sgdt _Original_GDTR # save original GDT
+ movzwl _Original_GDTR_limit,%ecx # size of GDT in bytes; limit
+ # is 8192 entries * 8 bytes per
+
+ # make ds:esi point to the original GDT
+
+ movl _Original_GDTR_base,%esi
+ push %ds # save ds
+ movw %gs,%ax
+ movw %ax,%ds
+
+ # make es:edi point to the new (our copy) GDT
+ movl $_Global_descriptor_table,%edi
+
+ rep
+ movsb # copy the GDT (ds:esi -> es:edi)
+
+ pop %ds # restore ds
+
+ # Build and load new contents of GDTR
+ movw _Original_GDTR_limit,%ecx # set new limit
+ movw %cx,_New_GDTR_limit
+
+ push $_Global_descriptor_table
+ push %es
+ call _Logical_to_physical
+ addl $6,%esp
+ movl %eax,_New_GDTR_base # set new base
+
+ cmpb $0,_Do_Load_GDT # Should the new GDT be loaded?
+ je no_gdt_load # NO, then branch
+ lgdt _New_GDTR # load the new GDT
+no_gdt_load:
+
+#
+# Copy the Interrupt Descriptor Table to our space
+#
+
+ sidt _Original_IDTR # save original IDT
+ movzwl _Original_IDTR_limit,%ecx # size of IDT in bytes; limit
+ # is 256 entries * 8 bytes per
+
+
+ # make ds:esi point to the original IDT
+ movl _Original_IDTR_base,%esi
+
+ push %ds # save ds
+ movw %gs,%ax
+ movw %ax,%ds
+
+ # make es:edi point to the new (our copy) IDT
+ movl $_Interrupt_descriptor_table,%edi
+
+ rep
+ movsb # copy the IDT (ds:esi -> es:edi)
+ pop %ds # restore ds
+
+ # Build and load new contents of IDTR
+ movw _Original_IDTR_limit,%ecx # set new limit
+ movw %cx,_New_IDTR_limit
+
+ push $_Interrupt_descriptor_table
+ push %es
+ call _Logical_to_physical
+ addl $6,%esp
+ movl %eax,_New_IDTR_base # set new base
+
+ cmpb $0,_Do_Load_IDT # Should the new IDT be loaded?
+ je no_idt_load # NO, then branch
+ lidt _New_IDTR # load the new IDT
+no_idt_load:
+
+#
+# Initialize the i387.
+#
+# Using the NO WAIT form of the instruction insures that if
+# it is not present the board will not lock up or get an
+# exception.
+#
+
+ fninit # MUST USE NO-WAIT FORM
+
+ call __Board_Initialize # initialize the board
+
+ pushl $0 # envp = NULL
+ pushl $0 # argv = NULL
+ pushl $0 # argc = NULL
+ call ___libc_init # initialize the library and
+ # call main
+ addl $12,%esp
+
+ pushl $0 # argc = NULL
+ call __exit # call the Board specific exit
+ addl $4,%esp
+
+#
+# Clean up
+#
+
+
+ .global _Bsp_cleanup
+
+ .global _return_to_monitor
+
+_Bsp_cleanup:
+ cmpb $0,_Do_Load_IDT # Was the new IDT loaded?
+ je no_idt_restore # NO, then branch
+ lidt _Original_IDTR # restore the new IDT
+no_idt_restore:
+
+ cmpb $0,_Do_Load_GDT # Was the new GDT loaded?
+ je no_gdt_restore # NO, then branch
+ lgdt _Original_GDTR # restore the new GDT
+no_gdt_restore:
+ jmp _return_to_monitor
+
+#
+# void *Logical_to_physical(
+# rtems_unsigned16 segment,
+# void *address
+# );
+#
+# Returns thirty-two bit physical address for segment:address.
+#
+
+ .global _Logical_to_physical
+
+.set SEGMENT_ARG, 4
+.set ADDRESS_ARG, 8
+
+_Logical_to_physical:
+
+ xorl %eax,%eax # clear eax
+ movzwl SEGMENT_ARG(%esp),%ecx # ecx = segment value
+ movl $_Global_descriptor_table,%edx # edx = address of our GDT
+ addl %ecx,%edx # edx = address of desired entry
+ movb 7(%edx),%ah # ah = base 31:24
+ movb 4(%edx),%al # al = base 23:16
+ shll $16,%eax # move ax into correct bits
+ movw 2(%edx),%ax # ax = base 0:15
+ movl ADDRESS_ARG(%esp),%ecx # ecx = address to convert
+ addl %eax,%ecx # ecx = physical address equivalent
+ movl %ecx,%eax # eax = ecx
+ ret
+
+#
+# void *Physical_to_logical(
+# rtems_unsigned16 segment,
+# void *address
+# );
+#
+# Returns thirty-two bit physical address for segment:address.
+#
+
+ .global _Physical_to_logical
+
+#.set SEGMENT_ARG, 4
+#.set ADDRESS_ARG, 8 -- use sets from above
+
+_Physical_to_logical:
+
+ xorl %eax,%eax # clear eax
+ movzwl SEGMENT_ARG(%esp),%ecx # ecx = segment value
+ movl $_Global_descriptor_table,%edx # edx = address of our GDT
+ addl %ecx,%edx # edx = address of desired entry
+ movb 7(%edx),%ah # ah = base 31:24
+ movb 4(%edx),%al # al = base 23:16
+ shll $16,%eax # move ax into correct bits
+ movw 2(%edx),%ax # ax = base 0:15
+ movl ADDRESS_ARG(%esp),%ecx # ecx = address to convert
+ subl %eax,%ecx # ecx = logical address equivalent
+ movl %ecx,%eax # eax = ecx
+ ret
+
+
+/*
+ * Data Declarations. Start with a macro which helps declare space.
+ */
+
+ .bss
+
+#define DECLARE_SPACE(_name,_space,_align) \
+ .globl _name ; \
+ .align _align ; \
+_name##: .space _space
+
+#define DECLARE_LABEL(_name) \
+ .globl _name ; \
+_name##:
+
+#define DECLARE_PTR(_name) DECLARE_SPACE(_name,4,2)
+#define DECLARE_U32(_name) DECLARE_SPACE(_name,4,2)
+#define DECLARE_U16(_name) DECLARE_SPACE(_name,2,1)
+
+/*
+ * Require environment stuff
+ */
+
+DECLARE_LABEL(_environ)
+DECLARE_PTR(environ)
+
+DECLARE_LABEL(_errno)
+DECLARE_U32(errno)
+
+/*
+ * Miscellaneous Variables used to restore the CPU state.
+ *
+ * Start with a macro to declare the space for the contents of
+ * a Descriptor Table register.
+ */
+
+#define DECLARE_DTR_SPACE(_name) \
+ .global _name ; \
+ .align 4 ; \
+_name##: ; \
+_name##_limit: .space 2 ; \
+_name##_base: .space 4
+
+DECLARE_SPACE(_Interrupt_descriptor_table,256*8,4)
+DECLARE_SPACE(_Global_descriptor_table,8192*8,4)
+
+DECLARE_DTR_SPACE(_Original_IDTR)
+DECLARE_DTR_SPACE(_New_IDTR)
+DECLARE_DTR_SPACE(_Original_GDTR)
+DECLARE_DTR_SPACE(_New_GDTR)
+
+DECLARE_SPACE(_Physical_base_of_ds,4,4)
+DECLARE_SPACE(_Physical_base_of_cs,4,4)
+
+/*
+ * Stack Size and Space
+ */
+
+ .set stack_size, 0x20000
+
+DECLARE_SPACE(stack_memory,stack_size,4)
+DECLARE_LABEL(stack_end)
+
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