Import of the watch repository from Pebble

third_party/ARM/Source/TransformFunctions/arm_bitreversal2.S

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+;/* ----------------------------------------------------------------------
+;* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
+;*
+;* $Date:       19. March 2015 
+;* $Revision: 	V.1.4.5
+;*
+;* Project: 	CMSIS DSP Library
+;* Title:	    arm_bitreversal2.S
+;*
+;* Description:	This is the arm_bitreversal_32 function done in
+;*              assembly for maximum speed.  This function is called
+;*              after doing an fft to reorder the output.  The function
+;*              is loop unrolled by 2. arm_bitreversal_16 as well.
+;*
+;* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
+;*
+;* Redistribution and use in source and binary forms, with or without
+;* modification, are permitted provided that the following conditions
+;* are met:
+;*   - Redistributions of source code must retain the above copyright
+;*     notice, this list of conditions and the following disclaimer.
+;*   - 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.
+;*   - Neither the name of ARM LIMITED nor the names of its contributors
+;*     may be used to endorse or promote products derived from this
+;*     software without specific prior written permission.
+;*
+;* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
+;* COPYRIGHT OWNER 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.
+;* -------------------------------------------------------------------- */
+#if defined(__CC_ARM)       // Keil
+    #define CODESECT AREA     ||.text||, CODE, READONLY, ALIGN=2
+    #define LABEL
+#elif defined(__IASMARM__)  // IAR
+    #define CODESECT SECTION `.text`:CODE
+    #define PROC
+    #define LABEL
+    #define ENDP
+    #define EXPORT PUBLIC
+#elif defined(__CSMC__)		/* Cosmic */
+	#define	CODESECT	switch .text
+	#define THUMB
+	#define EXPORT	xdef
+	#define PROC	:
+	#define LABEL	:
+	#define ENDP
+	#define arm_bitreversal_32 _arm_bitreversal_32
+#elif defined (__GNUC__)    // GCC
+    #define THUMB .thumb
+    #define CODESECT .section .text
+    #define EXPORT .global
+    #define PROC :
+    #define LABEL :
+    #define ENDP
+    #define END
+
+    .syntax unified
+#endif
+
+	CODESECT
+	THUMB
+
+;/*
+;* @brief  In-place bit reversal function.
+;* @param[in, out] *pSrc        points to the in-place buffer of unknown 32-bit data type.
+;* @param[in]      bitRevLen    bit reversal table length
+;* @param[in]      *pBitRevTab  points to bit reversal table.
+;* @return none.
+;*/
+	EXPORT arm_bitreversal_32
+	EXPORT arm_bitreversal_16
+
+#if defined(ARM_MATH_CM0) || defined(ARM_MATH_CM0PLUS)
+
+arm_bitreversal_32 PROC
+	ADDS     r3,r1,#1
+	PUSH     {r4-r6}
+	ADDS     r1,r2,#0
+	LSRS     r3,r3,#1
+arm_bitreversal_32_0 LABEL
+	LDRH     r2,[r1,#2]
+	LDRH     r6,[r1,#0]
+	ADD      r2,r0,r2
+	ADD      r6,r0,r6
+	LDR      r5,[r2,#0]
+	LDR      r4,[r6,#0]
+	STR      r5,[r6,#0]
+	STR      r4,[r2,#0]
+	LDR      r5,[r2,#4]
+	LDR      r4,[r6,#4]
+	STR      r5,[r6,#4]
+	STR      r4,[r2,#4]
+	ADDS     r1,r1,#4
+	SUBS     r3,r3,#1
+	BNE      arm_bitreversal_32_0
+	POP      {r4-r6}
+	BX       lr
+	ENDP
+
+arm_bitreversal_16 PROC
+	ADDS     r3,r1,#1
+	PUSH     {r4-r6}
+	ADDS     r1,r2,#0
+	LSRS     r3,r3,#1
+arm_bitreversal_16_0 LABEL
+	LDRH     r2,[r1,#2]
+	LDRH     r6,[r1,#0]
+    LSRS     r2,r2,#1
+    LSRS     r6,r6,#1
+	ADD      r2,r0,r2
+	ADD      r6,r0,r6
+	LDR      r5,[r2,#0]
+	LDR      r4,[r6,#0]
+	STR      r5,[r6,#0]
+	STR      r4,[r2,#0]
+	ADDS     r1,r1,#4
+	SUBS     r3,r3,#1
+	BNE      arm_bitreversal_16_0
+	POP      {r4-r6}
+	BX       lr
+	ENDP
+
+#else
+
+arm_bitreversal_32 PROC
+	ADDS     r3,r1,#1
+	CMP      r3,#1
+	IT       LS
+	BXLS     lr
+	PUSH     {r4-r9}
+	ADDS     r1,r2,#2
+	LSRS     r3,r3,#2
+arm_bitreversal_32_0 LABEL       ;/* loop unrolled by 2 */
+	LDRH     r8,[r1,#4]
+	LDRH     r9,[r1,#2]
+	LDRH     r2,[r1,#0]
+	LDRH     r12,[r1,#-2]
+	ADD      r8,r0,r8
+	ADD      r9,r0,r9
+	ADD      r2,r0,r2
+	ADD      r12,r0,r12
+	LDR      r7,[r9,#0]
+	LDR      r6,[r8,#0]
+	LDR      r5,[r2,#0]
+	LDR      r4,[r12,#0]
+	STR      r6,[r9,#0]
+	STR      r7,[r8,#0]
+	STR      r5,[r12,#0]
+	STR      r4,[r2,#0]
+	LDR      r7,[r9,#4]
+	LDR      r6,[r8,#4]
+	LDR      r5,[r2,#4]
+	LDR      r4,[r12,#4]
+	STR      r6,[r9,#4]
+	STR      r7,[r8,#4]
+	STR      r5,[r12,#4]
+	STR      r4,[r2,#4]
+	ADDS     r1,r1,#8
+	SUBS     r3,r3,#1
+	BNE      arm_bitreversal_32_0
+	POP      {r4-r9}
+	BX       lr
+	ENDP
+
+arm_bitreversal_16 PROC
+	ADDS     r3,r1,#1
+	CMP      r3,#1
+	IT       LS
+	BXLS     lr
+	PUSH     {r4-r9}
+	ADDS     r1,r2,#2
+	LSRS     r3,r3,#2
+arm_bitreversal_16_0 LABEL       ;/* loop unrolled by 2 */
+	LDRH     r8,[r1,#4]
+	LDRH     r9,[r1,#2]
+	LDRH     r2,[r1,#0]
+	LDRH     r12,[r1,#-2]
+	ADD      r8,r0,r8,LSR #1
+	ADD      r9,r0,r9,LSR #1
+	ADD      r2,r0,r2,LSR #1
+	ADD      r12,r0,r12,LSR #1
+	LDR      r7,[r9,#0]
+	LDR      r6,[r8,#0]
+	LDR      r5,[r2,#0]
+	LDR      r4,[r12,#0]
+	STR      r6,[r9,#0]
+	STR      r7,[r8,#0]
+	STR      r5,[r12,#0]
+	STR      r4,[r2,#0]
+	ADDS     r1,r1,#8
+	SUBS     r3,r3,#1
+	BNE      arm_bitreversal_16_0
+	POP      {r4-r9}
+	BX       lr
+	ENDP
+
+#endif
+
+	END