nf_asm.S

#ifndef NF_ASM_S
#define NF_ASM_S

/*
 * nf_asm.s - GCC NatFeats ASM detection code
 *
 * Copyright (c) 2014 by Eero Tamminen
 *
 * Mostly based on code from EmuTOS,
 * Copyright (c) 2001-2013 by the EmuTOS development team
 *
 * This file is distributed under the GPL, version 2 or at your
 * option any later version.
 *
 * TODO: test this
 */

/*
 * public interface
 */
	.globl  _nf_id
	.globl  _nf_call
	.globl  _detect_nf

/* illegal exception vector */
	.equ vec_illegal, 0x10

/*
 * code
 */
	.text

/*
 * NatFeats test
 *
 * Needs to be called from Supervisor mode,
 * otherwise exception handler change bombs
 */
_detect_nf:
	clr.l   d0			/* assume no NatFeats available */
	move.l  sp,a1
	move.l  vec_illegal,a0
#ifndef __mcoldfire__
	move.l  #fail_nf,vec_illegal
#endif
	pea     nf_version_name
	sub.l   #4,sp
#ifdef __mcoldfire__
#warning Conflict with instruction mvs.b d0,d1
#else
	.dc.w   0x7300			/* Jump to NATFEAT_ID */
#endif
	tst.l   d0
	beq.s   fail_nf
	moveq   #1,d0			/* NatFeats detected */

fail_nf:
	move.l  a1,sp
	move.l  a0,vec_illegal

	rts

nf_version_name:
	.ascii  "NF_VERSION\0"
	.even

/*
 * map native features to NF ID
 */
_nf_id:
	.dc.w   0x7300			/* Conflict with ColdFire instruction mvs.b d0,d1 */
	rts

/*
 * call native feature by its ID
 */
_nf_call:
	.dc.w   0x7301			/* Conflict with ColdFire instruction mvs.b d1,d1 */
	rts
#endif // NF_ASM_S