From de064ac74b8ed1b26441562fbd9e3975a7a9dc67 Mon Sep 17 00:00:00 2001
From: Matt Jenkins <matt@majenko.co.uk>
Date: Fri, 11 Apr 2014 10:20:46 +0100
Subject: [PATCH] Moved rdisk.c into kernel. Renamed startup.S to _startup.S

---
 sys/{pic32 => kernel}/rdisk.c |   0
 sys/pic32/_startup.S          | 406 +++++++++++++++++++++++++++++++++-
 sys/pic32/startup.S           | 405 ---------------------------------
 3 files changed, 405 insertions(+), 406 deletions(-)
 rename sys/{pic32 => kernel}/rdisk.c (100%)
 mode change 120000 => 100644 sys/pic32/_startup.S
 delete mode 100644 sys/pic32/startup.S

diff --git a/sys/pic32/rdisk.c b/sys/kernel/rdisk.c
similarity index 100%
rename from sys/pic32/rdisk.c
rename to sys/kernel/rdisk.c
diff --git a/sys/pic32/_startup.S b/sys/pic32/_startup.S
deleted file mode 120000
index cac3df3..0000000
--- a/sys/pic32/_startup.S
+++ /dev/null
@@ -1 +0,0 @@
-startup.S
\ No newline at end of file
diff --git a/sys/pic32/_startup.S b/sys/pic32/_startup.S
new file mode 100644
index 0000000..dddbdee
--- /dev/null
+++ b/sys/pic32/_startup.S
@@ -0,0 +1,405 @@
+#
+# Startup code for Microchip PIC32 microcontrollers.
+# Using HID bootloader.
+#
+# Copyright (C) 2010 Serge Vakulenko, <serge@vak.ru>
+#
+# Permission to use, copy, modify, and distribute this software
+# and its documentation for any purpose and without fee is hereby
+# granted, provided that the above copyright notice appear in all
+# copies and that both that the copyright notice and this
+# permission notice and warranty disclaimer appear in supporting
+# documentation, and that the name of the author not be used in
+# advertising or publicity pertaining to distribution of the
+# software without specific, written prior permission.
+#
+# The author disclaim all warranties with regard to this
+# software, including all implied warranties of merchantability
+# and fitness.  In no event shall the author be liable for any
+# special, indirect or consequential damages or any damages
+# whatsoever resulting from loss of use, data or profits, whether
+# in an action of contract, negligence or other tortious action,
+# arising out of or in connection with the use or performance of
+# this software.
+#
+#include "machine/io.h"
+
+#define UBASE	0x7f008000	/* User space base address */
+
+		.set	noreorder
+		.set	mips32r2
+		.set	nomips16
+
+		.extern	u
+		.extern	u_end
+		.extern	u0
+		.extern	main
+		.extern exception
+
+#---------------------------------------
+# Reset vector: main entry point
+#
+		.section .startup,"ax",@progbits
+		.org	0
+		.type	_reset_vector_, @function
+_reset_vector_:	.globl	_reset_vector_
+
+		.set	noat
+		move    $1, $zero                       # Clear all regs
+		move    $2, $zero
+		move    $3, $zero
+		move    $4, $zero
+		move    $5, $zero
+		move    $6, $zero
+		move    $7, $zero
+		move    $8, $zero
+		move    $9, $zero
+		move    $10, $zero
+		move    $11, $zero
+		move    $12, $zero
+		move    $13, $zero
+		move    $14, $zero
+		move    $15, $zero
+		move    $16, $zero
+		move    $17, $zero
+		move    $18, $zero
+		move    $19, $zero
+		move    $20, $zero
+		move    $21, $zero
+		move    $22, $zero
+		move    $23, $zero
+		move    $24, $zero
+		move    $25, $zero
+		move    $26, $zero
+		move    $27, $zero
+		move    $28, $zero
+		move    $29, $zero
+		move    $30, $zero
+		move    $31, $zero
+		mtlo	$zero
+		mthi	$zero
+		.set	at
+
+		la	$sp, u_end - 16			# Stack at end of U area
+                la      $a0, main
+		jalr	$a0				# Jump to main()
+		lui	$gp, 0x8000			# Set global pointer (delay slot)
+
+                la      $k0, UBASE
+		mtc0	$k0, $C0_EPC                    # Entry to user code.
+
+		mfc0	$k0, $C0_STATUS
+		ori	$k0, $k0, ST_UM | ST_EXL | ST_IE # Set user mode and enable interrupts
+		mtc0	$k0, $C0_STATUS			# Put SR back
+		ehb
+		eret					# PC <= EPC; EXL <= 0
+		nop					# just to be safe
+
+
+#---------------------------------------
+# Secondary entry point for RetroBSD bootloader.
+#
+		.section .exception,"ax",@progbits
+_exception_base_: .globl _exception_base_
+
+		.org	0
+		.type	_entry_vector_, @function
+_entry_vector_: .globl  _entry_vector_
+                la      $k0, _reset_vector_
+                jr      $k0
+                nop
+
+#---------------------------------------
+# Exception vector: handle interrupts and exceptions
+#
+		.org	0x200
+		.type	_exception_vector_, @function
+_exception_vector_: .globl _exception_vector_
+
+		mfc0	$k0, $C0_STATUS
+		andi	$k1, $k0, ST_UM			# Check user mode
+		beqz	$k1, kernel_exception
+		move	$k1, $sp
+
+		#
+		# Exception in user mode: switch stack.
+		#
+user_exception:
+		la	$sp, u_end                      # Stack at end of U area
+kernel_exception:
+		addi    $sp, -16-FRAME_WORDS*4		# Allocate space for registers
+save_regs:
+		sw	$k0, (16+FRAME_STATUS*4) ($sp)
+                sw      $k1, (16+FRAME_SP*4) ($sp)
+
+		.set	noat
+		sw	$1, (16+FRAME_R1*4) ($sp)	# Save general registers
+		sw	$2, (16+FRAME_R2*4) ($sp)
+		sw	$3, (16+FRAME_R3*4) ($sp)
+		sw	$4, (16+FRAME_R4*4) ($sp)
+		sw	$5, (16+FRAME_R5*4) ($sp)
+		sw	$6, (16+FRAME_R6*4) ($sp)
+		sw	$7, (16+FRAME_R7*4) ($sp)
+		sw	$8, (16+FRAME_R8*4) ($sp)
+		sw	$9, (16+FRAME_R9*4) ($sp)
+		sw	$10, (16+FRAME_R10*4) ($sp)
+		sw	$11, (16+FRAME_R11*4) ($sp)
+		sw	$12, (16+FRAME_R12*4) ($sp)
+		sw	$13, (16+FRAME_R13*4) ($sp)
+		sw	$14, (16+FRAME_R14*4) ($sp)
+		sw	$15, (16+FRAME_R15*4) ($sp)
+		sw	$16, (16+FRAME_R16*4) ($sp)
+		sw	$17, (16+FRAME_R17*4) ($sp)
+		sw	$18, (16+FRAME_R18*4) ($sp)
+		sw	$19, (16+FRAME_R19*4) ($sp)
+		sw	$20, (16+FRAME_R20*4) ($sp)
+		sw	$21, (16+FRAME_R21*4) ($sp)
+		sw	$22, (16+FRAME_R22*4) ($sp)
+		sw	$23, (16+FRAME_R23*4) ($sp)
+		sw	$24, (16+FRAME_R24*4) ($sp)
+		sw	$25, (16+FRAME_R25*4) ($sp)
+		# Skip $26 - K0
+		# Skip $27 - K1
+		sw	$28, (16+FRAME_GP*4) ($sp)
+		# Skip $29 - SP
+		sw	$30, (16+FRAME_FP*4) ($sp)
+		sw	$31, (16+FRAME_RA*4) ($sp)
+		.set	at
+
+		mfhi	$k0				# Save special registers
+		sw	$k0, (16+FRAME_HI*4) ($sp)
+
+		mflo	$k0
+		sw	$k0, (16+FRAME_LO*4) ($sp)
+
+		mfc0	$k0, $C0_EPC
+		sw	$k0, (16+FRAME_PC*4) ($sp)
+
+		move	$a0, $sp
+		addi	$a0, 16				# Arg 0: saved regs.
+		jal	exception			# Call C code.
+		lui	$gp, 0x8000			# Set global pointer (delay slot)
+
+		#
+		# Restore CPU state and return from interrupt.
+		#
+restore_regs:
+		lw	$a0, (16+FRAME_LO*4) ($sp)	# Load HI, LO registers
+		mtlo	$a0
+		lw	$a0, (16+FRAME_HI*4) ($sp)
+		mthi	$a0
+
+		.set	noat
+		lw	$1, (16+FRAME_R1*4) ($sp)	# Load general registers
+		lw	$2, (16+FRAME_R2*4) ($sp)
+		lw	$3, (16+FRAME_R3*4) ($sp)
+		lw	$4, (16+FRAME_R4*4) ($sp)
+		lw	$5, (16+FRAME_R5*4) ($sp)
+		lw	$6, (16+FRAME_R6*4) ($sp)
+		lw	$7, (16+FRAME_R7*4) ($sp)
+		lw	$8, (16+FRAME_R8*4) ($sp)
+		lw	$9, (16+FRAME_R9*4) ($sp)
+		lw	$10, (16+FRAME_R10*4) ($sp)
+		lw	$11, (16+FRAME_R11*4) ($sp)
+		lw	$12, (16+FRAME_R12*4) ($sp)
+		lw	$13, (16+FRAME_R13*4) ($sp)
+		lw	$14, (16+FRAME_R14*4) ($sp)
+		lw	$15, (16+FRAME_R15*4) ($sp)
+		lw	$16, (16+FRAME_R16*4) ($sp)
+		lw	$17, (16+FRAME_R17*4) ($sp)
+		lw	$18, (16+FRAME_R18*4) ($sp)
+		lw	$19, (16+FRAME_R19*4) ($sp)
+		lw	$20, (16+FRAME_R20*4) ($sp)
+		lw	$21, (16+FRAME_R21*4) ($sp)
+		lw	$22, (16+FRAME_R22*4) ($sp)
+		lw	$23, (16+FRAME_R23*4) ($sp)
+		lw	$24, (16+FRAME_R24*4) ($sp)
+		lw	$25, (16+FRAME_R25*4) ($sp)
+		# Skip $26 - K0
+		# Skip $27 - K1
+		lw	$28, (16+FRAME_GP*4) ($sp)
+		# Skip $29 - SP
+		lw	$30, (16+FRAME_FP*4) ($sp)
+		.set	at
+
+                # Do not use k0/k1 here, as interrupts are still enabled
+		lw	$31, (16+FRAME_STATUS*4) ($sp)	# K0 = saved status
+		ori	$31, ST_EXL                     # Set EXL
+		mtc0	$31, $C0_STATUS			# put SR back: disable interrupts
+                ehb
+
+		lw	$k0, (16+FRAME_PC*4) ($sp)	# K0 = EPC
+		mtc0	$k0, $C0_EPC			# put PC in EPC
+                ext     $k1, $31, 27, 1                 # get RP bit: single-step request
+
+		lw	$31, (16+FRAME_RA*4) ($sp)
+		lw	$sp, (16+FRAME_SP*4) ($sp)	# Restore stack
+
+		# Return from exception
+                bnez    $k1, debug_request              # single-step request
+		ehb
+		eret					# PC <= EPC; EXL <= 0
+debug_request:
+		sdbbp					# enter debug mode
+
+#---------------------------------------
+# Debug exception processing.
+#
+		.org	0x480
+		.type	_debug_vector_, @function
+_debug_vector_: .globl _debug_vector_
+
+		mfc0	$k0, $C0_DEPC
+		la	$k1, debug_request
+		bne     $k0, $k1, single_step_done
+		nop
+
+                # single step request
+		mfc0	$k0, $C0_DEBUG
+		ori     $k0, DB_SST                     # set SST bit
+		mtc0	$k0, $C0_DEBUG
+
+		mfc0	$k1, $C0_EPC
+		mtc0	$k1, $C0_DEPC                   # DEPC <= EPC
+		mfc0	$k0, $C0_STATUS
+		xori	$k0, ST_EXL                     # Clear EXL
+		mtc0	$k0, $C0_STATUS
+		ehb
+		deret					# PC <= DEPC; DM <= 0
+
+single_step_done:
+		mtc0	$k0, $C0_EPC                    # EPC <= DEPC
+
+		la      $k1, _exception_vector_
+		mtc0	$k1, $C0_DEPC                   # DEPC <= exception handler
+
+		mfc0	$k0, $C0_DEBUG
+		sw	$k0, c0_debug                   # save Debug register
+		ori     $k0, DB_SST
+		xori    $k0, DB_SST                     # clear SST bit
+		mtc0	$k0, $C0_DEBUG
+
+		mfc0	$k1, $C0_STATUS
+		ori	$k1, ST_EXL                     # Set EXL
+		mtc0	$k1, $C0_STATUS
+		ehb
+		deret					# PC <= DEPC; DM <= 0
+
+#---------------------------------------
+# Icode is copied out to process 1 to exec /sbin/init.
+# If the exec fails, process 1 exits.
+#
+		.globl	icode, icodeend
+		.type	icode, @function
+		.type	icodeend, @function
+icode:
+		la	$a0, UBASE
+		move	$a1, $a0
+		addi	$a0, etcinit - icode
+		addi	$a1, argv - icode
+		syscall	11				# SYS_execv
+		move	$a0, $v0
+		syscall	1				# SYS_exit
+etcinit:
+		.ascii	"/sbin/init\0"
+initflags:
+		.ascii	"-\0"                          # ASCII initflags
+argv:
+		.word	etcinit + 6 - icode + UBASE	# address of "init\0"
+		.word	initflags - icode + UBASE	# init options
+		.word	0
+
+icodeend:	nop
+
+#---------------------------------------
+# int setjmp (label_t *env);
+#
+# Setjmp(env) will save the process' current register variables, stack
+# and program counter context and return a zero.
+#
+		.type	setjmp, @function
+setjmp:		.globl	setjmp
+		sw	$s0, (0 * 4) ($a0)		# save register variables s0-s8
+		sw	$s1, (1 * 4) ($a0)
+		sw	$s2, (2 * 4) ($a0)
+		sw	$s3, (3 * 4) ($a0)
+		sw	$s4, (4 * 4) ($a0)
+		sw	$s5, (5 * 4) ($a0)
+		sw	$s6, (6 * 4) ($a0)
+		sw	$s7, (7 * 4) ($a0)
+		sw	$s8, (8 * 4) ($a0)		# frame pointer
+		sw	$ra, (9 * 4) ($a0)		# return address
+		sw	$gp, (10 * 4) ($a0)		# global data pointer
+		sw	$sp, (11 * 4) ($a0)		# stack pointer
+		j	$ra
+		move	$v0, $zero			# return a zero for the setjmp call
+
+#---------------------------------------
+# void longjmp (memaddr uaddr, label_t *env);
+#
+# Longjmp(uaddr, env) will generate a "return(1)" from the last
+# call to setjmp(env) by mapping in the user structure pointed to by uaddr,
+# restoring the context saved by setjmp in env and returning a "1".
+# Note that registers are recovered statically from the env buffer.
+# Stack is not used.
+#
+# This longjmp differs from the longjmp found in the standard library -
+# it's actually closer to the resume routine of the 4.3BSD kernel.
+#
+		.type	longjmp, @function
+longjmp:	.globl	longjmp
+
+		di				# can't let anything in till we get a valid stack...
+
+		la	$v0, u			# pointer to &u
+		beq	$v0, $a0, 2f		# if uaddr == &u...
+		nop				# ...no need to remap U area
+
+		la	$a3, u_end		# pointer to &u + USIZE
+		la	$a0, u0			# pointer to &u0
+
+		lw	$v1, 0($v0)		# u.u_procp
+		sw	$a0, 60($v1)		# u.u_procp->p_addr = &u0
+
+		# exchange contents of u and u0
+		move	$v1, $v0
+1:
+                lw	$t1, 0($v1)
+                lw	$t0, 0($a0)
+                sw	$t0, 0($v1)
+                sw	$t1, 0($a0)
+                lw	$t1, 4($v1)
+                lw	$t0, 4($a0)
+                sw	$t0, 4($v1)
+                sw	$t1, 4($a0)
+                lw	$t1, 8($v1)
+                lw	$t0, 8($a0)
+                sw	$t0, 8($v1)
+                sw	$t1, 8($a0)
+                lw	$t1, 12($v1)
+                lw	$t0, 12($a0)
+                sw	$t0, 12($v1)
+                sw	$t1, 12($a0)
+                addiu	$v1, $v1, 16
+                bne	$a3, $v1, 1b
+                addiu	$a0, $a0, 16
+
+		lw	$v1, 0($v0)		# u.u_procp
+		sw	$v0, 60($v1)		# u.u_procp->p_addr = &u
+2:
+		lw	$s0, (0 * 4) ($a1)	# restore register variables s0-s8
+		lw	$s1, (1 * 4) ($a1)
+		lw	$s2, (2 * 4) ($a1)
+		lw	$s3, (3 * 4) ($a1)
+		lw	$s4, (4 * 4) ($a1)
+		lw	$s5, (5 * 4) ($a1)
+		lw	$s6, (6 * 4) ($a1)
+		lw	$s7, (7 * 4) ($a1)
+		lw	$s8, (8 * 4) ($a1)	# frame pointer
+		lw	$ra, (9 * 4) ($a1)	# return address
+		lw	$gp, (10 * 4) ($a1)	# global data pointer
+		lw	$sp, (11 * 4) ($a1)	# stack pointer
+
+		ei				# release interrupts
+		j	$ra			# transfer back to setjmp()
+		li	$v0, 1			# return value of 1
diff --git a/sys/pic32/startup.S b/sys/pic32/startup.S
deleted file mode 100644
index dddbdee..0000000
--- a/sys/pic32/startup.S
+++ /dev/null
@@ -1,405 +0,0 @@
-#
-# Startup code for Microchip PIC32 microcontrollers.
-# Using HID bootloader.
-#
-# Copyright (C) 2010 Serge Vakulenko, <serge@vak.ru>
-#
-# Permission to use, copy, modify, and distribute this software
-# and its documentation for any purpose and without fee is hereby
-# granted, provided that the above copyright notice appear in all
-# copies and that both that the copyright notice and this
-# permission notice and warranty disclaimer appear in supporting
-# documentation, and that the name of the author not be used in
-# advertising or publicity pertaining to distribution of the
-# software without specific, written prior permission.
-#
-# The author disclaim all warranties with regard to this
-# software, including all implied warranties of merchantability
-# and fitness.  In no event shall the author be liable for any
-# special, indirect or consequential damages or any damages
-# whatsoever resulting from loss of use, data or profits, whether
-# in an action of contract, negligence or other tortious action,
-# arising out of or in connection with the use or performance of
-# this software.
-#
-#include "machine/io.h"
-
-#define UBASE	0x7f008000	/* User space base address */
-
-		.set	noreorder
-		.set	mips32r2
-		.set	nomips16
-
-		.extern	u
-		.extern	u_end
-		.extern	u0
-		.extern	main
-		.extern exception
-
-#---------------------------------------
-# Reset vector: main entry point
-#
-		.section .startup,"ax",@progbits
-		.org	0
-		.type	_reset_vector_, @function
-_reset_vector_:	.globl	_reset_vector_
-
-		.set	noat
-		move    $1, $zero                       # Clear all regs
-		move    $2, $zero
-		move    $3, $zero
-		move    $4, $zero
-		move    $5, $zero
-		move    $6, $zero
-		move    $7, $zero
-		move    $8, $zero
-		move    $9, $zero
-		move    $10, $zero
-		move    $11, $zero
-		move    $12, $zero
-		move    $13, $zero
-		move    $14, $zero
-		move    $15, $zero
-		move    $16, $zero
-		move    $17, $zero
-		move    $18, $zero
-		move    $19, $zero
-		move    $20, $zero
-		move    $21, $zero
-		move    $22, $zero
-		move    $23, $zero
-		move    $24, $zero
-		move    $25, $zero
-		move    $26, $zero
-		move    $27, $zero
-		move    $28, $zero
-		move    $29, $zero
-		move    $30, $zero
-		move    $31, $zero
-		mtlo	$zero
-		mthi	$zero
-		.set	at
-
-		la	$sp, u_end - 16			# Stack at end of U area
-                la      $a0, main
-		jalr	$a0				# Jump to main()
-		lui	$gp, 0x8000			# Set global pointer (delay slot)
-
-                la      $k0, UBASE
-		mtc0	$k0, $C0_EPC                    # Entry to user code.
-
-		mfc0	$k0, $C0_STATUS
-		ori	$k0, $k0, ST_UM | ST_EXL | ST_IE # Set user mode and enable interrupts
-		mtc0	$k0, $C0_STATUS			# Put SR back
-		ehb
-		eret					# PC <= EPC; EXL <= 0
-		nop					# just to be safe
-
-
-#---------------------------------------
-# Secondary entry point for RetroBSD bootloader.
-#
-		.section .exception,"ax",@progbits
-_exception_base_: .globl _exception_base_
-
-		.org	0
-		.type	_entry_vector_, @function
-_entry_vector_: .globl  _entry_vector_
-                la      $k0, _reset_vector_
-                jr      $k0
-                nop
-
-#---------------------------------------
-# Exception vector: handle interrupts and exceptions
-#
-		.org	0x200
-		.type	_exception_vector_, @function
-_exception_vector_: .globl _exception_vector_
-
-		mfc0	$k0, $C0_STATUS
-		andi	$k1, $k0, ST_UM			# Check user mode
-		beqz	$k1, kernel_exception
-		move	$k1, $sp
-
-		#
-		# Exception in user mode: switch stack.
-		#
-user_exception:
-		la	$sp, u_end                      # Stack at end of U area
-kernel_exception:
-		addi    $sp, -16-FRAME_WORDS*4		# Allocate space for registers
-save_regs:
-		sw	$k0, (16+FRAME_STATUS*4) ($sp)
-                sw      $k1, (16+FRAME_SP*4) ($sp)
-
-		.set	noat
-		sw	$1, (16+FRAME_R1*4) ($sp)	# Save general registers
-		sw	$2, (16+FRAME_R2*4) ($sp)
-		sw	$3, (16+FRAME_R3*4) ($sp)
-		sw	$4, (16+FRAME_R4*4) ($sp)
-		sw	$5, (16+FRAME_R5*4) ($sp)
-		sw	$6, (16+FRAME_R6*4) ($sp)
-		sw	$7, (16+FRAME_R7*4) ($sp)
-		sw	$8, (16+FRAME_R8*4) ($sp)
-		sw	$9, (16+FRAME_R9*4) ($sp)
-		sw	$10, (16+FRAME_R10*4) ($sp)
-		sw	$11, (16+FRAME_R11*4) ($sp)
-		sw	$12, (16+FRAME_R12*4) ($sp)
-		sw	$13, (16+FRAME_R13*4) ($sp)
-		sw	$14, (16+FRAME_R14*4) ($sp)
-		sw	$15, (16+FRAME_R15*4) ($sp)
-		sw	$16, (16+FRAME_R16*4) ($sp)
-		sw	$17, (16+FRAME_R17*4) ($sp)
-		sw	$18, (16+FRAME_R18*4) ($sp)
-		sw	$19, (16+FRAME_R19*4) ($sp)
-		sw	$20, (16+FRAME_R20*4) ($sp)
-		sw	$21, (16+FRAME_R21*4) ($sp)
-		sw	$22, (16+FRAME_R22*4) ($sp)
-		sw	$23, (16+FRAME_R23*4) ($sp)
-		sw	$24, (16+FRAME_R24*4) ($sp)
-		sw	$25, (16+FRAME_R25*4) ($sp)
-		# Skip $26 - K0
-		# Skip $27 - K1
-		sw	$28, (16+FRAME_GP*4) ($sp)
-		# Skip $29 - SP
-		sw	$30, (16+FRAME_FP*4) ($sp)
-		sw	$31, (16+FRAME_RA*4) ($sp)
-		.set	at
-
-		mfhi	$k0				# Save special registers
-		sw	$k0, (16+FRAME_HI*4) ($sp)
-
-		mflo	$k0
-		sw	$k0, (16+FRAME_LO*4) ($sp)
-
-		mfc0	$k0, $C0_EPC
-		sw	$k0, (16+FRAME_PC*4) ($sp)
-
-		move	$a0, $sp
-		addi	$a0, 16				# Arg 0: saved regs.
-		jal	exception			# Call C code.
-		lui	$gp, 0x8000			# Set global pointer (delay slot)
-
-		#
-		# Restore CPU state and return from interrupt.
-		#
-restore_regs:
-		lw	$a0, (16+FRAME_LO*4) ($sp)	# Load HI, LO registers
-		mtlo	$a0
-		lw	$a0, (16+FRAME_HI*4) ($sp)
-		mthi	$a0
-
-		.set	noat
-		lw	$1, (16+FRAME_R1*4) ($sp)	# Load general registers
-		lw	$2, (16+FRAME_R2*4) ($sp)
-		lw	$3, (16+FRAME_R3*4) ($sp)
-		lw	$4, (16+FRAME_R4*4) ($sp)
-		lw	$5, (16+FRAME_R5*4) ($sp)
-		lw	$6, (16+FRAME_R6*4) ($sp)
-		lw	$7, (16+FRAME_R7*4) ($sp)
-		lw	$8, (16+FRAME_R8*4) ($sp)
-		lw	$9, (16+FRAME_R9*4) ($sp)
-		lw	$10, (16+FRAME_R10*4) ($sp)
-		lw	$11, (16+FRAME_R11*4) ($sp)
-		lw	$12, (16+FRAME_R12*4) ($sp)
-		lw	$13, (16+FRAME_R13*4) ($sp)
-		lw	$14, (16+FRAME_R14*4) ($sp)
-		lw	$15, (16+FRAME_R15*4) ($sp)
-		lw	$16, (16+FRAME_R16*4) ($sp)
-		lw	$17, (16+FRAME_R17*4) ($sp)
-		lw	$18, (16+FRAME_R18*4) ($sp)
-		lw	$19, (16+FRAME_R19*4) ($sp)
-		lw	$20, (16+FRAME_R20*4) ($sp)
-		lw	$21, (16+FRAME_R21*4) ($sp)
-		lw	$22, (16+FRAME_R22*4) ($sp)
-		lw	$23, (16+FRAME_R23*4) ($sp)
-		lw	$24, (16+FRAME_R24*4) ($sp)
-		lw	$25, (16+FRAME_R25*4) ($sp)
-		# Skip $26 - K0
-		# Skip $27 - K1
-		lw	$28, (16+FRAME_GP*4) ($sp)
-		# Skip $29 - SP
-		lw	$30, (16+FRAME_FP*4) ($sp)
-		.set	at
-
-                # Do not use k0/k1 here, as interrupts are still enabled
-		lw	$31, (16+FRAME_STATUS*4) ($sp)	# K0 = saved status
-		ori	$31, ST_EXL                     # Set EXL
-		mtc0	$31, $C0_STATUS			# put SR back: disable interrupts
-                ehb
-
-		lw	$k0, (16+FRAME_PC*4) ($sp)	# K0 = EPC
-		mtc0	$k0, $C0_EPC			# put PC in EPC
-                ext     $k1, $31, 27, 1                 # get RP bit: single-step request
-
-		lw	$31, (16+FRAME_RA*4) ($sp)
-		lw	$sp, (16+FRAME_SP*4) ($sp)	# Restore stack
-
-		# Return from exception
-                bnez    $k1, debug_request              # single-step request
-		ehb
-		eret					# PC <= EPC; EXL <= 0
-debug_request:
-		sdbbp					# enter debug mode
-
-#---------------------------------------
-# Debug exception processing.
-#
-		.org	0x480
-		.type	_debug_vector_, @function
-_debug_vector_: .globl _debug_vector_
-
-		mfc0	$k0, $C0_DEPC
-		la	$k1, debug_request
-		bne     $k0, $k1, single_step_done
-		nop
-
-                # single step request
-		mfc0	$k0, $C0_DEBUG
-		ori     $k0, DB_SST                     # set SST bit
-		mtc0	$k0, $C0_DEBUG
-
-		mfc0	$k1, $C0_EPC
-		mtc0	$k1, $C0_DEPC                   # DEPC <= EPC
-		mfc0	$k0, $C0_STATUS
-		xori	$k0, ST_EXL                     # Clear EXL
-		mtc0	$k0, $C0_STATUS
-		ehb
-		deret					# PC <= DEPC; DM <= 0
-
-single_step_done:
-		mtc0	$k0, $C0_EPC                    # EPC <= DEPC
-
-		la      $k1, _exception_vector_
-		mtc0	$k1, $C0_DEPC                   # DEPC <= exception handler
-
-		mfc0	$k0, $C0_DEBUG
-		sw	$k0, c0_debug                   # save Debug register
-		ori     $k0, DB_SST
-		xori    $k0, DB_SST                     # clear SST bit
-		mtc0	$k0, $C0_DEBUG
-
-		mfc0	$k1, $C0_STATUS
-		ori	$k1, ST_EXL                     # Set EXL
-		mtc0	$k1, $C0_STATUS
-		ehb
-		deret					# PC <= DEPC; DM <= 0
-
-#---------------------------------------
-# Icode is copied out to process 1 to exec /sbin/init.
-# If the exec fails, process 1 exits.
-#
-		.globl	icode, icodeend
-		.type	icode, @function
-		.type	icodeend, @function
-icode:
-		la	$a0, UBASE
-		move	$a1, $a0
-		addi	$a0, etcinit - icode
-		addi	$a1, argv - icode
-		syscall	11				# SYS_execv
-		move	$a0, $v0
-		syscall	1				# SYS_exit
-etcinit:
-		.ascii	"/sbin/init\0"
-initflags:
-		.ascii	"-\0"                          # ASCII initflags
-argv:
-		.word	etcinit + 6 - icode + UBASE	# address of "init\0"
-		.word	initflags - icode + UBASE	# init options
-		.word	0
-
-icodeend:	nop
-
-#---------------------------------------
-# int setjmp (label_t *env);
-#
-# Setjmp(env) will save the process' current register variables, stack
-# and program counter context and return a zero.
-#
-		.type	setjmp, @function
-setjmp:		.globl	setjmp
-		sw	$s0, (0 * 4) ($a0)		# save register variables s0-s8
-		sw	$s1, (1 * 4) ($a0)
-		sw	$s2, (2 * 4) ($a0)
-		sw	$s3, (3 * 4) ($a0)
-		sw	$s4, (4 * 4) ($a0)
-		sw	$s5, (5 * 4) ($a0)
-		sw	$s6, (6 * 4) ($a0)
-		sw	$s7, (7 * 4) ($a0)
-		sw	$s8, (8 * 4) ($a0)		# frame pointer
-		sw	$ra, (9 * 4) ($a0)		# return address
-		sw	$gp, (10 * 4) ($a0)		# global data pointer
-		sw	$sp, (11 * 4) ($a0)		# stack pointer
-		j	$ra
-		move	$v0, $zero			# return a zero for the setjmp call
-
-#---------------------------------------
-# void longjmp (memaddr uaddr, label_t *env);
-#
-# Longjmp(uaddr, env) will generate a "return(1)" from the last
-# call to setjmp(env) by mapping in the user structure pointed to by uaddr,
-# restoring the context saved by setjmp in env and returning a "1".
-# Note that registers are recovered statically from the env buffer.
-# Stack is not used.
-#
-# This longjmp differs from the longjmp found in the standard library -
-# it's actually closer to the resume routine of the 4.3BSD kernel.
-#
-		.type	longjmp, @function
-longjmp:	.globl	longjmp
-
-		di				# can't let anything in till we get a valid stack...
-
-		la	$v0, u			# pointer to &u
-		beq	$v0, $a0, 2f		# if uaddr == &u...
-		nop				# ...no need to remap U area
-
-		la	$a3, u_end		# pointer to &u + USIZE
-		la	$a0, u0			# pointer to &u0
-
-		lw	$v1, 0($v0)		# u.u_procp
-		sw	$a0, 60($v1)		# u.u_procp->p_addr = &u0
-
-		# exchange contents of u and u0
-		move	$v1, $v0
-1:
-                lw	$t1, 0($v1)
-                lw	$t0, 0($a0)
-                sw	$t0, 0($v1)
-                sw	$t1, 0($a0)
-                lw	$t1, 4($v1)
-                lw	$t0, 4($a0)
-                sw	$t0, 4($v1)
-                sw	$t1, 4($a0)
-                lw	$t1, 8($v1)
-                lw	$t0, 8($a0)
-                sw	$t0, 8($v1)
-                sw	$t1, 8($a0)
-                lw	$t1, 12($v1)
-                lw	$t0, 12($a0)
-                sw	$t0, 12($v1)
-                sw	$t1, 12($a0)
-                addiu	$v1, $v1, 16
-                bne	$a3, $v1, 1b
-                addiu	$a0, $a0, 16
-
-		lw	$v1, 0($v0)		# u.u_procp
-		sw	$v0, 60($v1)		# u.u_procp->p_addr = &u
-2:
-		lw	$s0, (0 * 4) ($a1)	# restore register variables s0-s8
-		lw	$s1, (1 * 4) ($a1)
-		lw	$s2, (2 * 4) ($a1)
-		lw	$s3, (3 * 4) ($a1)
-		lw	$s4, (4 * 4) ($a1)
-		lw	$s5, (5 * 4) ($a1)
-		lw	$s6, (6 * 4) ($a1)
-		lw	$s7, (7 * 4) ($a1)
-		lw	$s8, (8 * 4) ($a1)	# frame pointer
-		lw	$ra, (9 * 4) ($a1)	# return address
-		lw	$gp, (10 * 4) ($a1)	# global data pointer
-		lw	$sp, (11 * 4) ($a1)	# stack pointer
-
-		ei				# release interrupts
-		j	$ra			# transfer back to setjmp()
-		li	$v0, 1			# return value of 1