📄 iir32_mac.s.list
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;*********************************************
;* Freescale Semiconductor Inc.
;* (c) Copyright 2001 Freescale Semiconductor Inc.
;* ALL RIGHTS RESERVED.
;*********************************************
;* FILE NAME: iir32.s
;*********************************************
.section .text ;-=Locate the code in the ".text" section.=-
.align 4
.xdef _IIR32_MAC
;******************************************************
;* NAME: void IIR32( struct tIirStruct *pIIR, Frac32* pX, Frac32* pY, unsigned int n)
;*
;* DESCRIPTION: Computes a Infinite Impulse Response (IIR) filter for a array of 32-bit fractional data values.
;******************************************************
;* a2 pIIR - Pointer to a data structure containing private data for the iir filter
;* 68(a7) pX - Pointer to the input vector of n data elements
;* 72(a7) pY - Pointer to the output vector of n data elements
;* d6 n - Length of the input and output vectors
;* d2 k - Counter for inner loop
;* d1 i - Counter for outer loop
;* d0 N - Length of coefficients vector(N<=n)
;* a0 pCurY - Pointer to the current Y
;* a1 pCurX - Pointer to the current X
;* a3 pCurCoef - Pointer to the current coefficient
;* a4 pCurHistory - Pointer to the current element of history buffer
;* a5 pPredY - Pointer to the previous Y
;* acc output - Accumulator
;******************************************************
_IIR32_MAC
;---=Saving values of used registers=---
0x00000000: 4fefffc4 lea -60(a7),a7
0x00000004: 48d77fff movem.l d0-d7/a0-a6,(a7)
;---=Most useful parameters are moved from stack to registers.=---
0x00000008: 2c2f004c move.l 76(a7),d6 ; n - Length of the input and output vectors
0x0000000c: 206f0048 move.l 72(a7),a0 ; pCurY=pY; - Pointer to the current Y.
0x00000010: 226f0044 move.l 68(a7),a1 ; pCurX=pX; - Pointer to the current X.
0x00000014: 246f0040 move.l 64(a7),a2 ; -=N=pIIR->iIirCoefCount/2+1;=-
0x00000018: 202a0004 move.l 4(a2),d0
0x0000001c: e288 lsr.l #1,d0
0x0000001e: 5280 addq.l #1,d0
;---====== Begin of cycle of getting Y[1]..Y[N-1] ======---
0x00000020: 7201 moveq #1,d1 ; for(i=1;i<N;i++) -=Begin of outer loop (number 1)=-
.FORi1
0x00000022: b280 cmp.l d0,d1 ; -=Comparing "i" with "N"
0x00000024: 64000070 bcc .ENDFORi1 ; { -=If (i=>N) then jump to .ENDFORi1=-
0x00000028: a13c00000000 move.l #0,acc ; -=Accumulator initialization=-
0x0000002e: 2c6f0044 move.l 68(a7),a6 ; pCurX=pX+i-1; -=Current sample pointer initialization=-
0x00000032: 43f61c00 lea (0,a6,d1.l*4),a1 ;
0x00000036: 2c6f0048 move.l 72(a7),a6 ; pPredY=pY+i-2; -=Previous Y pointer initialization=-
0x0000003a: 4bf61cfc lea (-4,a6,d1.l*4),a5
;---== Begin of cycle Getting Y[i] ==---
0x0000003e: 2652 move.l (a2),a3 ; pCurCoef=pIIR->pIirCoef; -=Current coefficient pointer initialization=-
;;-=output=*pCurX--*(*pCurCoef++);=-
0x00000040: 2621 move.l -(a1),d3 ; -=Getting current sample=-
0x00000042: 281b move.l (a3)+,d4 ; -=Getting current coefficient=-
0x00000044: a8030ac0 mac.l d3,d4,<< ; -=Getting first iteration of inner loop=-
0x00000048: 7401 moveq #1,d2 ; for(k=1;k<i;k++) -=Begin of inner loop=-
0x0000004a: 281b move.l (a3)+,d4 ; -=Getting next current coefficient=-
.FORk1 ; {
0x0000004c: b481 cmp.l d1,d2 ; -=Comparing "k" with "i"=-
0x0000004e: 64000012 bcc .ENDFORk1 ; -=If (k=>i) then jump to .ENDFORk1=-
;-=output+=*pCurX--*(*pCurCoef++);=-
0x00000052: 2621 move.l -(a1),d3 ; -=Getting next current sample=-
0x00000054: a89b4ac3 mac.l d3,d4,<<,(a3)+,d4 ; -=First MAC and getting next current coefficient=-
;-=output+=*pPredY--*(*pCurCoef++);=-
0x00000058: 2625 move.l -(a5),d3 ; -=Getting previous Y=-
0x0000005a: a89b4ac3 mac.l d3,d4,<<,(a3)+,d4 ; -=Second MAC and getting next current coefficient=-
0x0000005e: 5282 addq.l #1,d2 ; -=Incrementing "k"=-
0x00000060: 60ea bra .FORk1 ; -=Jumping to .FORk1=-
.ENDFORk1 ; }
;---==Testing that History Buffer is filled => this is not first calling of this function==--
0x00000062: 4aaa000c tst.l 12(a2) ; if(pIIR->iIirHistoryCount>0) -=Testing that pFIR->iFirHistoryCount>0=-
0x00000066: 67000026 beq .ENDFORk2 ; { -=If (pFIR->iFirHistoryCount=0) then jump to .ENDFORk2=-
0x0000006a: 2c6a0008 move.l 8(a2),a6 ; pCurHistory=pIIR->pIirHistory+pIIR->iIirHistoryCount-1;
0x0000006e: 2e2a000c move.l 12(a2),d7
0x00000072: 49f67c00 lea (0,a6,d7.l*4),a4
0x00000076: 2401 move.l d1,d2 ; for(k=i;k<N;k++) -=Begin of inner loop=-
.FORk2
0x00000078: b480 cmp.l d0,d2 ; -=Comparing "k" with "N"=-
0x0000007a: 64000012 bcc .ENDFORk2 ; { -=If (k=>N) then jump to .ENDFORk2=-
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