/*

 Package: dyncall
 Library: dyncall
 File: dyncall/dyncall_call_arm32_arm_armhf.S
 Description: Call Kernel for ARM 32-bit ARM Architecture - Hard Float
 License:

   Copyright (c) 2007-2015 Daniel Adler <dadler@uni-goettingen.de>, 
                           Tassilo Philipp <tphilipp@potion-studios.com>

   Permission to use, copy, modify, and distribute this software for any
   purpose with or without fee is hereby granted, provided that the above
   copyright notice and this permission notice appear in all copies.

   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS 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, DIRECT, 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 "../portasm/portasm-arm.S"

/* ============================================================================
   DynCall Call Kernel for ARM 32-bit ARM Architecture Hard-Float
   ----------------------------------------------------------------------------
   C Interface:
     dcCall_arm32_armhf (DCpointer target, DCpointer argv, DCsize size, DCfloat* regdata);

   This Call Kernel was tested on Raspberry Pi/Raspbian (Debian)
*/

.text
.code 32	/* ARM mode */
.arch armv6
.fpu  vfp

/*
  1st arg / r0 = funptr
  2st arg / r1 = ptr to int args
  3st arg / r2 = size
  4st arg / r3 = ptr to float args
*/
GLOBAL_C(dcCall_arm32_armhf)
ENTRY_C(dcCall_arm32_armhf)

	/* Prolog. This function never needs to spill inside its prolog, so just store the permanent registers. */
	mov	r12 , r13	 /* Stack ptr (r13) -> temporary (r12). */
	stmdb	r13!, {r4-r5, r11, r12, r14} /* Permanent registers and stack pointer (now in r12), etc... -> save area on stack (except counter). */

	mov	r11 , r12	 /* Set frame ptr. */
	mov	r4  , r0 	 /* r4 = 'fptr' (1st argument is passed in r0). */
	mov	r5  , r1	 /* r5 = 'args' (2nd argument is passed in r1). */
	
	/* Load 16 single-precision registers (= 8 double-precision registers). */
	fldmiad	r3, {d0-d7}

	sub	r2 , r2 , #16	/* skip spill area */
	cmp     r2, #0
	ble	armhf_call

	sub	r13, r13, r2
	and	r13, r13, #-8	/* align 8-byte. */

	mov	r3, #0		/* Init byte counter. */
	add	r1 , r1 , #16
armhf_pushArgs:
	ldr	r0, [r1,  +r3]	/* Load word into r0. */
	str	r0, [r13, +r3]	/* Push word onto stack. */
	add	r3, r3, #4	/* Increment byte counter. */
	cmp	r2, r3
	bne	armhf_pushArgs

armhf_call:
	ldmia	r5, {r0-r3}	/* Load first 4 arguments for new call into r0-r3. */
				/* 'blx %r4' workaround for ARMv4t: */
	mov	r14, r15	/*   Branch return address(r15) -> link register (r14) -- r15 always points to address of current + 2 instructions (= Epilog code). */ 
	bx	r4		/*   Call (ARM/THUMB), available for ARMv4t. */

	/* Epilog. */
	ldmdb	r11, {r4-r5, r11, r13, r15}	/* Restore permanent registers (ignore temporary (r12), restore stack ptr and program counter).@@@db not needed since we rewrite r13? */