freebsd-dev/sys/libkern/arm/ldivmod.S
2013-03-16 04:08:01 +00:00

70 lines
2.6 KiB
ArmAsm

/*
* Copyright (C) 2012 Andrew Turner
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#include <machine/asm.h>
__FBSDID("$FreeBSD$");
#ifdef __ARM_EABI__
/*
* These calculate:
* q = n / m
* With a remainer r.
*
* They take n in {r0, r1} and m in {r2, r3} then pass them into the
* helper function. The hepler functions return q in {r0, r1} as
* required by the API spec however r is returned on the stack. The
* ABI required us to return r in {r2, r3}.
*
* We need to allocate 8 bytes on the stack to store r, the link
* register, and a pointer to the space where the helper function
* will write r to. After returning from the helper fuinction we load
* the old link register and r from the stack and return.
*/
ENTRY_NP(__aeabi_ldivmod)
sub sp, sp, #8 /* Space for the remainder */
stmfd sp!, {sp, lr} /* Save a pointer to the above space and lr */
bl PIC_SYM(_C_LABEL(__kern_ldivmod), PLT)
ldr lr, [sp, #4] /* Restore lr */
add sp, sp, #8 /* Move sp to the remainder value */
ldmfd sp!, {r2, r3} /* Load the remainder */
RET
END(__aeabi_ldivmod)
ENTRY_NP(__aeabi_uldivmod)
sub sp, sp, #8 /* Space for the remainder */
stmfd sp!, {sp, lr} /* Save a pointer to the above space and lr */
bl PIC_SYM(_C_LABEL(__qdivrem), PLT)
ldr lr, [sp, #4] /* Restore lr */
add sp, sp, #8 /* Move sp to the remainder value */
ldmfd sp!, {r2, r3} /* Load the remainder */
RET
END(__aeabi_uldivmod)
#endif