ARM version of central ADPCM decoding block for NDS. Define ARM_ADPCM to

enable.

Apparently may not be required as this isn't speed critical - but I've
written it now, so seems a shame to lose it.

svn-id: r29980

backends/platform/ds/arm9/source/adpcm_arm.s

@@ -0,0 +1,108 @@
+@ ScummVM Scumm Interpreter
+@ Copyright (C) 2007 The ScummVM project
+@
+@ This program is free software@ you can redistribute it and/or
+@ modify it under the terms of the GNU General Public License
+@ as published by the Free Software Foundation@ either version 2
+@ of the License, or (at your option) any later version.
+@
+@ This program is distributed in the hope that it will be useful,
+@ but WITHOUT ANY WARRANTY; without even the implied warranty of
+@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+@ GNU General Public License for more details.
+@
+@ You should have received a copy of the GNU General Public License
+@ along with this program@ if not, write to the Free Software
+@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+@
+@ $URL:  $
+@ $Id:  $
+@
+@ @author Robin Watts (robin@wss.co.uk)
+
+	.global	ARM_adpcm
+	.section .itcm,"ax", %progbits
+	.align 2
+	.code 32
+
+	@ ARM implementation of inner ADPCM decoding loop
+	@
+	@ C prototype would be:
+	@
+	@ extern "C" void ARM_adpcm(int *block,
+	@                           int  len,
+	@                           int  stepTableIndex,
+	@                           int  firstSample,
+	@                           s16 *decompressionBuffer)
+ARM_adpcm
+	@ r0 = block
+	@ r1 = len
+	@ r2 = stepTableIndex
+	@ r3 = firstSample
+	@ <> = decompressionBuffer
+	STMFD	r13!,{r4-r11,r14}
+	LDR	r4,[r13,#4*9]
+
+	LDR	r12,[r0],#4	@ r12 = word = block[r>>3]
+	MOV	r14,#0
+	ADR	r11,stepTab
+	ADR	r7, indexTab
+	MOV	r2, r2, LSL #1	@ r2 = stepTableIndex*2 - hold it doubled
+	STR	r3, [r4],#2	@ decompBuff[0] = firstSample
+	MOV	r3, r3, LSL #16	@ r3 = firstSample<<16 (for saturated maths)
+	SUBS	r1, r1, #1
+	BLE	end
+loop:
+	LDRH	r10,[r11,r2]	@ r10 = stepTab[stepTableIndex]
+	TST	r12,#4		@ if ((offset & 4) == 0)
+	MOVEQ	r9, #0		@ 	r9 = diff = 0
+	MOVNE	r9, r10		@ else	r9 = diff = stepTab[stepTableIndex]
+
+	TST	r12,#2		@ if (offset & 2)
+	ADDNE	r9, r9, r10,ASR #1	@ 	diff += r10>>1
+
+	TST	r12,#1		@ if (offset & 1)
+	ADDNE	r9, r9, r10,ASR #2	@ 	diff += r10>>2
+
+	ADD	r9, r9, r10,ASR #3	@ diff += r10>>3
+
+	TST	r12,#8		@ if (offset & 8
+	RSBNE	r9, r9, r10
+
+	ADDS	r3, r3, r9	@ r3 = newSample = prevSample+diff
+	RSCVS	r3, r3, #1<<31	@ r3 = clip(newSample)
+	MOV	r8, r3, LSR #16
+
+	AND	r6, r12,#4	@ r6 = offset
+	LDRB	r6, [r7,r6]	@ r6 = indexTab[offset]
+	MOV	r12,r12,LSR #4
+	STRH	r8, [r4],#2
+
+	ADDS	r2,r2,r6,LSL #1	@ r2 = stepTableIndex += indexTab[offset]
+	MOVLT	r2,#0
+	CMP	r2,#88*2
+	MOVGT	r2,#88*2
+	SUBS	r1,r1,#1
+	BEQ	end
+	SUBS	r14,r14,#0x10000000
+	LDREQ	r12,[r0],#4
+	B	loop
+
+end:
+	LDMFD	r13!,{r4-r11,PC}
+
+stepTab:
+	DCW	7, 8, 9, 10, 11, 12, 13, 14,
+	DCW	16, 17, 19, 21, 23, 25, 28, 31,
+	DCW	34, 37, 41, 45, 50, 55, 60, 66,
+	DCW	73, 80, 88, 97, 107, 118, 130, 143,
+	DCW	157, 173, 190, 209, 230, 253, 279, 307,
+	DCW	337, 371, 408, 449, 494, 544, 598, 658,
+	DCW	724, 796, 876, 963, 1060, 1166, 1282, 1411,
+	DCW	1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024,
+	DCW	3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
+	DCW	7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
+	DCW	15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794,
+	DCW	32767
+indexTab:
+	DCB -1, -1, -1, -1, 2, 4, 6, 8, -1, -1, -1, -1, 2, 4, 6, 8

backends/platform/ds/arm9/source/cdaudio.cpp

@@ -244,6 +244,11 @@ void update() {
 	playNextBlock();
 }
 
+#ifdef ARM_ADPCM
+extern "C" void ARM_adcpm(int *block, int len, int stepTableIndex,
+                          int firstSample, s16 *decompressionBuffer);
+#endif
+
 void decompressBlock() {
 	int block[2048];
 	bool loop = false;
@@ -294,7 +299,13 @@ void decompressBlock() {
 			return;
 		}
 	}
-		
+
+#ifdef ARM_ADPCM
+	ARM_adpcm(block, waveHeader.fmtExtra,
+	          blockHeader.stepTableIndex,
+	          blockHeader.firstSample,
+	          decompressionBuffer);
+#else		
 	// First sample is in header
 	decompressionBuffer[0] = blockHeader.firstSample;
 	
@@ -387,6 +398,7 @@ void decompressBlock() {
 		
 
 	}
+#endif
 }
 
 void playNextBlock() {