Initial Commit

common/embeddedaudiosynthesis/arm-wt-22k/lib_src/ARM-E_mastergain_gnu.s

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+@***********************************************************
+@ Function:    SynthMasterGain
+@ Processor:   ARM-E
+@ Description: Copies 32-bit synth output to 16-bit buffer
+@              with saturated gain control
+@              C-callable.
+@
+@ Usage: 
+@	SynthMasterGain(
+@			pInputBuffer
+@			pOutputBuffer,
+@			nGain,
+@			nNumLoopSamples
+@	);
+@
+@ Copyright Sonic Network Inc. 2004
+@****************************************************************
+@ Revision Control:
+@   $Revision: 496 $
+@   $Date: 2006-12-11 14:33:26 -0800 (Mon, 11 Dec 2006) $
+@****************************************************************
+@
+@   where:
+@	long *pInputBuffer
+@	PASSED IN: r0
+@
+@	EAS_PCM *pOutputBuffer
+@	PASSED IN: r1
+@
+@	short nGain
+@	PASSED IN: r2
+@
+@	EAS_U16	nNumLoopSamples
+@	PASSED IN: r3
+@
+@****************************************************************
+
+	.include	"ARM_synth_constants_gnu.inc"
+
+	.arm
+	.text
+
+	.func	SynthMasterGain
+SynthMasterGain:
+
+	.global	SynthMasterGain	@ allow other files to use this function
+	
+
+
+
+
+@ Stack frame
+@ -----------
+	.equ	RET_ADDR_SZ, 0			@return address
+	.equ	REG_SAVE_SZ, 0			@save-on-entry registers saved
+	.equ	FRAME_SZ, (8)			@local variables
+	.equ	ARG_BLK_SZ, 0			@argument block
+
+	.equ	PARAM_OFFSET, (ARG_BLK_SZ + FRAME_SZ + REG_SAVE_SZ + RET_ADDR_SZ)
+
+@ Register usage
+@ --------------
+pnInputBuffer	.req	r0
+pnOutputBuffer	.req	r1
+nGain	.req	r2
+nNumLoopSamples	.req	r3
+
+	STMFD	sp!,{r4-r6,r14}					@Save any save-on-entry registers that are used
+
+	LDR		r6, =0x7fff						@constant for saturation tests
+
+loop:
+	LDR		r4, [pnInputBuffer], #4			@fetch 1st output sample
+	
+	LDR		r5, [pnInputBuffer], #4			@fetch 2nd output sample
+
+	SMULWB	r4, r4, nGain					@output = gain * input
+	
+	CMP		r4, r6							@check for positive saturation
+	MOVGT	r4, r6							@saturate
+	CMN		r4, r6							@check for negative saturation
+	MVNLT	r4, r6							@saturate
+	
+	SMULWB	r5, r5, nGain					@output = gain * input
+	
+	STRH	r4, [pnOutputBuffer], #NEXT_OUTPUT_PCM	@save 1st output sample
+	
+	CMP		r5, r6							@check for positive saturation
+	MOVGT	r5, r6							@saturate
+	CMN		r5, r6							@check for negative saturation
+	MVNLT	r5, r6							@saturate
+	STRH	r5, [pnOutputBuffer], #NEXT_OUTPUT_PCM	@save 2nd output sample
+
+	SUBS	nNumLoopSamples, nNumLoopSamples, #2
+	BGT		loop
+
+@
+@ Return to calling function
+@----------------------------------------------------------------
+
+	LDMFD	sp!,{r4-r6, lr}				@ return to calling function
+	BX		lr
+
+@*****************************************************************************
+
+	.endfunc		@ end of function/procedure
+
+	.end		@ end of assembly code
+