From 9a404ca6d4020fa77c61d4cd210b924b06deaf94 Mon Sep 17 00:00:00 2001
From: Pierre Bourdon <delroth@gmail.com>
Date: Sat, 16 Mar 2013 23:54:55 +0100
Subject: [PATCH] Ship by default a free DSP ROM that can handle most games
 with LLE

At the end of July 2011, LM published a free DSP ROM that works with games
using the Zelda UCode. His ROM only has the code to handle UCode loading and a
few utility functions, the rest is missing. This includes the four large sound
mixing functions used by the AX UCode and the DROM containing coefficients used
for polyphase resampling in AX.

This is an improved, updated version of this ROM, which changes the following:

- We now have a free DROM that works for polyphase resampling by "emulating"
  linear interpolation. The coefficients contained in the DROM are normally a
  list of { c1, c2, c3, c4 } which are used to interpolate a sample value from
  four previous samples:
    out_sample = prev1 * c1 + prev2 * c2 + prev3 * c3 + prev4 * c4

  The coefficients are chosen depending on the fractional part of the current
  position (basically, our position between the previous and the next sample).
  We can use this fact to generate (c1, c2, c3, c4) for each possible
  fractional part so that:
    out_sample = prev3 * curr_pos + prev4 * (1 - curr_pos)

  Which is the formula for linear interpolation between prev3 and prev4. Linear
  interpolation is not as good as polyphase resampling but it still works very
  well and I couldn't really hear any difference between the two. If someone
  wants to generate real polyphase filter coefficients, they are welcome to
  submit a patch.

- The IROM now contains the 4 mixing functions used by the AX UCode: mix_add,
  mix_add_two, mix_add_ramp, mix_add_ramp_two. They are large, inlined
  functions (probably for performance reasons) in the official DSP IROM, our
  version prefers to use a loop. This *should* be more performant with our DSP
  JIT implementation, but I did not benchmark that.

Because the new DSP ROM is working just as well as the official ROM in 95% of
cases, it is now shipped by default with Dolphin and will be used with DSPLLE
if you don't have an official DSP ROM in User/GC. It will still display a panic
alert at every boot to notice you that you are using a non official DSP ROM
made by us, which is not perfect.

Games using the CARD, IPL or GBA UCodes are still broken. I don't know what
games this actually impacts, but this is a very small proportion compared to
what works.
---
 Data/Sys/GC/dsp_coef.bin                  |  Bin 0 -> 4096 bytes
 Data/Sys/GC/dsp_rom.bin                   |  Bin 0 -> 8192 bytes
 Source/Core/Core/Src/DSP/DSPCore.cpp      |   61 +-
 Source/Core/Core/Src/HW/DSPLLE/DSPLLE.cpp |    8 +-
 docs/DSP/dsp_rom_v0.1.rar                 |  Bin 2118 -> 0 bytes
 docs/DSP/free_dsp_rom/dsp_rom.ds          | 1169 +++++++++++++++++++++
 docs/DSP/free_dsp_rom/dsp_rom_readme.txt  |   28 +
 7 files changed, 1238 insertions(+), 28 deletions(-)
 create mode 100644 Data/Sys/GC/dsp_coef.bin
 create mode 100644 Data/Sys/GC/dsp_rom.bin
 delete mode 100644 docs/DSP/dsp_rom_v0.1.rar
 create mode 100644 docs/DSP/free_dsp_rom/dsp_rom.ds
 create mode 100644 docs/DSP/free_dsp_rom/dsp_rom_readme.txt

diff --git a/Data/Sys/GC/dsp_coef.bin b/Data/Sys/GC/dsp_coef.bin
new file mode 100644
index 0000000000000000000000000000000000000000..a276f2cede1a8e6936b4526f9621a391ca6b9515
GIT binary patch
literal 4096
zcmeIz)mD&E6h+}l34*jBNOwwicXufuDXny;kFGEuL;rJezWX)y8Vlg}pV#kALiB}D
zeI`tw2-im<^nrJJPo&-vrMJA-8>01^7`@_yUJ|Pp#OXQldPahtlBg#n=`qRri;wz~
z6g?tU5Ba1Ar0G8Cy2oeTB|~?})E{K&HrcvGj&72x8|3La`MO4dey31ZDbf{+b(s?V
zMyY<KOqVFvMJjZGN}cD6&QYbaRO<{iI!&!kQKysC>jVutPNR;|q@y(J2rW8Hs}9ko
zgS6`a9okQ)_R*!ibZZYi+D)%^(WjmCYX<|`&Y-q2q^%5V3nSXhs5UXCjf`sp6I#!t
z)-k2EOlu7@TFtChF{fXc*Gd+&f<-N7Nz3@ErF_#8mbI7_En-y*`K|@5X+G<k$A;#z
zsX1(EHrtxT56xspGuYM7>}fjtn#O^C;!smL(iDE`M}BEC$C|{6CUU9?oM}Ag8pnmk
za;YD<(ipBanj3x3twwRDk=*M$9yEeS4d+S2c-Bx}G~~7MZ!hS7t~mt#5BmRh2toft
d?L)Bt!T!G;La_h;_WoP;;0qE668P^D_zP_)!utRK

literal 0
HcmV?d00001

diff --git a/Data/Sys/GC/dsp_rom.bin b/Data/Sys/GC/dsp_rom.bin
new file mode 100644
index 0000000000000000000000000000000000000000..54e03da7c7a620df76054e8422f645a3c0b97da1
GIT binary patch
literal 8192
zcmeIzy-UMD7zXgiBSKx2F4dUBWQwz6A*;Apm#*rd)KPE|ha%U~#YOOAaM0R6p^M-m
z3HU`3KSsA8_%R8tLd|)(k|k@FmcE(Zdk&7|mwWGU2#F&Hg|65t{6*h;sDb&SgiuN}
zTO)O_V`1s!Mn<@mlAVhjngP=@uAaF|(pE2>)9HPZwtK0k)7K<@>8+j9X`s^!x61+n
zb|w~B=tjCe6(v=7SO7!iWfo#UpMAu(;|!7P;9Wl9Lq6kEKH^J0D1-9kMD`D3e(e`y
z+~D)P!cXFny<;1LYnEMvR!9q&#k^BD%vE#w2j+AeOE`eFYgIR4&)Dn3xL26pSkXOm
z8CR-fMu$-$y-#RN0{tvdQ}?OqO<nQpywj*y)kRpIy8GU^%hy!0ot$uHF@47IS-wFX
q-p~J*-i-uEfCNZ@1W14cNPq-LfCNZ@1W14cNPq-LfCNY&tH3|JmVa>o

literal 0
HcmV?d00001

diff --git a/Source/Core/Core/Src/DSP/DSPCore.cpp b/Source/Core/Core/Src/DSP/DSPCore.cpp
index 972eb53858..2594a27eef 100644
--- a/Source/Core/Core/Src/DSP/DSPCore.cpp
+++ b/Source/Core/Core/Src/DSP/DSPCore.cpp
@@ -77,37 +77,50 @@ static bool LoadRom(const char *fname, int size_in_words, u16 *rom)
 // Returns false iff the hash fails and the user hits "Yes"
 static bool VerifyRoms(const char *irom_filename, const char *coef_filename)
 {
-	static const u32 hash[] = { 0x66f334fe, 0xf3b93527 };
-	static const u32 hash_mini[] = { 0x9c8f593c, 0x10000001 };
-	static const int size[] = { DSP_IROM_BYTE_SIZE, DSP_COEF_BYTE_SIZE };
-	const u16 *data[] = { g_dsp.irom, g_dsp.coef };
-	u32 h = 0;
-	u8 count = 0;
-
-	for (int i = 0; i < 2; i++)
+	struct DspRomHashes
 	{
-		h = HashAdler32((u8*)data[i], size[i]);
+		u32 hash_irom;		// dsp_rom.bin
+		u32 hash_drom;		// dsp_coef.bin
+	} KNOWN_ROMS[] = {
+		// Official Nintendo ROM
+		{ 0x66f334fe, 0xf3b93527 },
 
-		if (h == hash_mini[i])
-		{
-			count++;
-		}
-		else if (h != hash[i])
-		{
-			if (AskYesNoT("%s has an incorrect hash.\n"
-				"Would you like to stop now to fix the problem?\n"
-				"If you select \"No\", audio will be garbled.",
-				(i == 0) ? irom_filename : coef_filename))
-				return false;
-		}
+		// LM1234 replacement ROM (Zelda UCode only)
+		{ 0x9c8f593c, 0x10000001 },
+
+		// delroth's improvement on LM1234 replacement ROM (Zelda and AX only,
+        // IPL/Card/GBA still broken)
+		{ 0xd9907f71, 0xb019c2fb }
+	};
+
+	u32 hash_irom = HashAdler32((u8*)g_dsp.irom, DSP_IROM_BYTE_SIZE);
+	u32 hash_drom = HashAdler32((u8*)g_dsp.coef, DSP_COEF_BYTE_SIZE);
+	int rom_idx = -1;
+
+	for (u32 i = 0; i < sizeof (KNOWN_ROMS) / sizeof (KNOWN_ROMS[0]); ++i)
+	{
+		DspRomHashes& rom = KNOWN_ROMS[i];
+		if (hash_irom == rom.hash_irom && hash_drom == rom.hash_drom)
+			rom_idx = i;
 	}
 
-	if (count == 2)
+	if (rom_idx < 0)
 	{
-		PanicAlertT("You are using free dsp roms made by Dolphin Team.\n"
-					"Only Zelda ucode games will work correctly with them.\n");
+		if (AskYesNoT("Your DSP ROMs have incorrect hashes.\n"
+			"Would you like to stop now to fix the problem?\n"
+			"If you select \"No\", audio might be garbled."))
+			return false;
 	}
 
+	if (rom_idx == 1)
+		PanicAlertT("You are using an old free DSP ROM made by the Dolphin Team.\n"
+					"Only games using the Zelda UCode will work correctly.\n");
+
+	if (rom_idx == 2)
+		PanicAlertT("You are using a free DSP ROM made by the Dolphin Team.\n"
+					"All Wii games will work correctly, and most GC games should "
+					"also work fine, but the GBA/IPL/CARD UCodes will not work.\n");
+
 	return true;
 }
 
diff --git a/Source/Core/Core/Src/HW/DSPLLE/DSPLLE.cpp b/Source/Core/Core/Src/HW/DSPLLE/DSPLLE.cpp
index 2cbf39f457..0b1dfe524d 100644
--- a/Source/Core/Core/Src/HW/DSPLLE/DSPLLE.cpp
+++ b/Source/Core/Core/Src/HW/DSPLLE/DSPLLE.cpp
@@ -144,13 +144,13 @@ bool DSPLLE::Initialize(void *hWnd, bool bWii, bool bDSPThread)
 	m_bDSPThread = bDSPThread;
 	m_InitMixer = false;
 
-	std::string irom_file = File::GetSysDirectory() + GC_SYS_DIR DIR_SEP DSP_IROM;
-	std::string coef_file = File::GetSysDirectory() + GC_SYS_DIR DIR_SEP DSP_COEF;
+	std::string irom_file = File::GetUserPath(D_GCUSER_IDX) + DSP_IROM;
+	std::string coef_file = File::GetUserPath(D_GCUSER_IDX) + DSP_COEF;
 
 	if (!File::Exists(irom_file))
-		irom_file = File::GetUserPath(D_GCUSER_IDX) + DSP_IROM;
+		irom_file = File::GetSysDirectory() + GC_SYS_DIR DIR_SEP DSP_IROM;
 	if (!File::Exists(coef_file))
-		coef_file = File::GetUserPath(D_GCUSER_IDX) + DSP_COEF;
+		coef_file = File::GetSysDirectory() + GC_SYS_DIR DIR_SEP DSP_COEF;
 	if (!DSPCore_Init(irom_file.c_str(), coef_file.c_str(), AudioCommon::UseJIT()))
 		return false;
 
diff --git a/docs/DSP/dsp_rom_v0.1.rar b/docs/DSP/dsp_rom_v0.1.rar
deleted file mode 100644
index dc12816b22ea8461a3a04a93cbd8bd8194222f53..0000000000000000000000000000000000000000
GIT binary patch
literal 0
HcmV?d00001

literal 2118
zcmZ9Mc{J2*AI5*#HHOA0Z9++iA+kh<GGom$_I->&mQ2iyEk$L^$bP(KELmd+BaO8%
zk7;|1B^o3#Bq=<MUBpYzIq!Mv^Ur<m`<(ka=lY)O`dVY~(ntA$o-_ggfPsHWU=yX%
z&H)GaZU+E>3j!Q}ZI`<PmrxS|q;}uD2tjD<b#EV-rymYj_|k<qkPcml_*uF5uB}7>
z{&9<IU<(wb4?NvfQ2{#kRCa%H)zYiS<9?}t{-=V!9{5Xys=R&~l78esCQCn~{xgci
zJ5^x(B%Curb7G|Md(@r;FrVq_+H;H(khDu|dUz(?i2JWu(l+Bz?#SrDTCs{mL{Wq!
zbHi@S92sQUe+uyJa5d1L>-dyc1G<Aw+JLIhKhUF%If%|!OMpH4R_wjoH`0v}Av#yh
zFkrvdj1LARoMaDoqR5C%1+wH#iz!*wX6yPOk;4CiKe;!$A1z6HZ-w<fp3_Lcao)8U
z+0PaUY%8QHzm>@_ktrkV?Hw7Y=-7J5u4QFlcpm^L3+!4hw)9C|CGQPx|8JJP2msY+
z0wN$`#q82O4rx&WErg0L)e)l^InCyuT|;B<9BDRrwd9$s84zRM{4p+elLga{OZO$C
z-i!n(#erV6g4HMMMi<Q$dy*%Z?j3rmJ|1zihMq=j$H;hmN9vD{4?ev87;YK<73C&L
z3(1oVyr$Y-X686Y3Bb&Xj|qDTxE+CB6K;Jq&(?Pd{^4Rf!L!*TdiQCHKw-)S<r{_C
znEPjy&eJSu2H5z67we0{BvTwDGIioQPoz{j`r)lmTk`J8BVIB^D;dJ5EPrr@MZ<Vq
zz`(or1#)s=w82xOou>V9Y1>Q4Qp6?q+W98W!m}cHiZT5;Z=>SWd4HQKtud;p3MYuv
z-C$sLTSY{fsZn?Xwy`De=fUF<wr`4S9Do5|xSNI5M!ahy&EExmRI>=UTJ^KDK<4wL
zrPL0y5o_N<PGNXAN0R3_C1iaQAEvZ*x6yTBsfklHq~g0?z#D_I07dAaN7lFLp#b3)
zIcJe~e*3L0%l-NhavMi)r9bg7GHj}>dxh`rDj|FgRn-k&;}yf-iX8Gx%BP~W(if_-
zzYT1aKhm`6@{gS_M@>eNpCmgJ33B?oG}bV-koq7O<mnmyd!lsolH7hu$nxYlXN!96
z^AU=&=25;LpLT<w1&ne5fPmO;5ZX5HHH!brKJ@>CfcEku5HN&57%`j(P!Yi*Li>ce
zz|gKs;;nbugxf!T<KxQ+ENPnT?1lo3e1clt6g@ygu#RY!t77?sZi@qnpN=IH7+0Wh
zo`sv{s{V;48V*ba?~G(IlLB)EZ=UiB-nELR^Urm$iWT2ycN9#wR|vs&KONR{QopW0
zJS#*YtYqfnLt`~;E1$NO*|Y5Gdd<;#HOl>&=e{)?1Ru8hj~3g(sgDQ7F<H!;8e9PN
z#-!R;N!KihrdEN{Mqn3YKEw|tIG`w5vweme;T=k~vXw0UTxm4S9dvWWxapE(cGSeN
ztVrM2H|-H=vUBS6lDNE`w)J9`ap@|rVRe4%<S_V)KJ(|-m(D($0*sZ_>FR{F(>%|T
zqAwRpyVIh|n2!k&j<`pt&1d!#SX1cDW#q-K;o~6A`4-Z=%wU2I*B~mV&Dy#LL}j~;
zhL!5J_l>wVkUdGY2*&td#Y&pgrS$ffP|+bW7L<+oG}SqMbh7>R5&El9c#2@aO1UaO
zcyfFJSIK?lrDS@=h=WNW>B=Fq2-=vlTi4iXvtYwp1&ypxTcP0xaCB2cVvg=xr^WAg
zOKq!dW|JfDg^WkJ{}7vp1v}-T%|g#e_p|2g=4CXqJB;;wbX$jAe4z4-2Gr=8r9dyV
z>6lE&+Ufc#i2$L|#jzTAwg3KF;b@)2DO~TTFXmMkw=d5cUo55fqq^JH*RH|O)QaEd
zJ9ToVQrXJUgX#<e3yVk|WCb<4-as&3oap@n_8%<#4rkvVK=x3S*O8#ronW~}w5$<l
zkVUG`Z(^NPUt4tGvYqbFGpM9a`RL8r<+%QxvLs6+uf@`5Pa#u0XEFF{AL%w5S$xW;
zt_l(%)#za}|N0^MSObL{VR}pc00VyOveMNS*(4&kUTk=oe*fvkrT8A%RAAdGrFyp&
znn3REdW_j^23O~)LuHQ(_SU25Z>_+4W4r>r|1AYijV$<%6*KwPVMy2tY#n~B2+8I0
zWKiE2Sz>$1TH&91NPDQ(h_&G%^o@#2U&E1y>=5Vb&SqZ{mf0PJ<xGvKoePFvRTCcz
zkFuVX?l^I*8Sf?Jtj2fc=X`8w+T?)a--#W?Av3AY+dJCP=$I1q66%<M3B>t&q4#4Z
zyH{OSXTl8sw`V&Kg4=MVWL7m>POHpBN>#(nx#s)H%VxUNQ0+6r7vC3el4a<U!k8*b
zP;lu3mqLXPw1&r4J1RlYhuYImR@Dk$qB4@r1T$wP@}+g;{Wmk|w{4>mI5C4aaxAcj
z0jv22#|EZ&JkEB)^sM&ne~b%OEANG7-7Yyy#SNof+1v?33pDZX?6;oCa2*8}hhb7r
zjj#=jKUQ8jkYv$IIUA7grsNCb-7Jcp{wGh**d9XY<|_*Hx-cD_n>I8<lo!O2h_D`p
zlL~S9T&gDi@`sgf*`XMfO=b@Vs;K`k*0Z8Vs$d@$HG@%IY}J+QOAxD$=y)W=;-%PZ
nhrtPR{KRF$PJVe7=>j^ewYg`}|CxR1*ZdWIhHfOF&ky_;tK#&>

diff --git a/docs/DSP/free_dsp_rom/dsp_rom.ds b/docs/DSP/free_dsp_rom/dsp_rom.ds
new file mode 100644
index 0000000000..bf1ee0c60f
--- /dev/null
+++ b/docs/DSP/free_dsp_rom/dsp_rom.ds
@@ -0,0 +1,1169 @@
+IROM_BASE:	equ 0x8000
+
+lri $CR, #0x00ff
+lri $SR, #0x2000
+si @DMBH, #0x8071
+si @DMBL, #0xfeed
+
+mainloop:
+	clr $ACC1
+	clr $ACC0
+	call wait_for_cpu_mbox+#IROM_BASE
+
+;mmem-addr	
+param1:
+	lr $AC1.M, @CMBL
+	lri $AC0.M, #0xa001
+	cmp
+	jnz param2+#IROM_BASE
+	call wait_for_cpu_mbox+#IROM_BASE
+	lr $IX0, @CMBH
+	lr $IX1, @CMBL
+	jmp mainloop+#IROM_BASE
+
+;iram-addr	
+param2:
+	lri $AC0.M, #0xc002
+	cmp
+	jnz param3+#IROM_BASE
+	call wait_for_cpu_mbox+#IROM_BASE
+	lr $IX2, @CMBL
+	jmp mainloop+#IROM_BASE
+
+;iram-length	
+param3:
+	lri $AC0.M, #0xa002
+	cmp
+	jnz param4+#IROM_BASE
+	call wait_for_cpu_mbox+#IROM_BASE
+	lr $IX3, @CMBL
+	jmp mainloop+#IROM_BASE
+
+;dram-length	
+param4:
+	lri $AC0.M, #0xb002
+	cmp
+	jnz param5+#IROM_BASE
+	call wait_for_cpu_mbox+#IROM_BASE
+	lr $AX0.L, @CMBL
+	jmp mainloop+#IROM_BASE	
+
+;iram-start-addr	
+param5:
+	lri $AC0.M, #0xd001
+	cmp
+	jnz mainloop+#IROM_BASE
+	call wait_for_cpu_mbox+#IROM_BASE
+	lr $AR0, @CMBL
+	jmp 0x80b5
+	
+wait_for_dsp_mbox:
+	lrs		$AC0.M, @DMBH
+	andcf	$AC0.M, #0x8000
+	jlz		wait_for_dsp_mbox+#IROM_BASE
+	ret
+
+wait_for_cpu_mbox:
+	lrs		$AC0.M, @CMBH
+	andcf	$AC0.M, #0x8000
+	jlnz	wait_for_cpu_mbox+#IROM_BASE
+	ret
+	
+wait_dma:
+	lrs		$AC0.M, @DSCR
+	andcf	$AC0.M, #0x0004
+	jlz		wait_dma+#IROM_BASE
+	ret
+	
+bootucode:	
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop	
+	nop	
+	nop	
+	nop	
+	nop	
+	nop	
+	nop	
+	nop		
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop
+	nop	
+	nop	
+	nop	
+	nop	
+	nop	
+	nop	
+	nop	
+	nop		
+	nop		
+	nop		
+	nop		
+	nop		
+	nop		
+	nop		
+	nop		
+	nop		
+
+sub_80b5:
+	set16       
+	clr  $ACC1
+	clr  $ACC0
+	lris $AC0.M, #0x2
+	sr   @DSCR, $AC0.M
+	sr   @DSMAH, $IX0
+	sr   @DSMAL, $IX1
+	sr   @DSPA, $IX2
+	sr   @DSBL, $IX3
+	call wait_dma+#IROM_BASE
+	jmpr $AR0
+
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+
+; 80e7
+; Args:
+; AR0 points to the 32 input 1 samples (s16)
+; AR1 points to the volume data (init1, delta1, init2, delta2)
+; AR2 points to the already mixed samples for output 1 (s32)
+; AR3 points to where the output 1 should be stored (s32)
+; IX0 points to the 32 input 2 samples (s16)
+; IX1 points to where the output 2 should be stored (s32)
+;
+; Returns:
+; AX0.L is the value of the last sample from input 1
+; AX1.H is the value of the last sample from input 2
+mix_two_add:
+    call mix_add+#IROM_BASE
+    iar $AR1
+    mrr $AR0, $IX0
+    mrr $AR2, $IX1
+    mrr $AR3, $IX1
+    mrr $IX0, $AX0.L
+    call mix_add+#IROM_BASE
+    mrr $AX1.H, $AX0.L
+    mrr $AX0.L, $IX0
+    ret
+
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+
+; 81f9
+; Args:
+; AR0 points to the 32 input samples (s16)
+; AR1 points to the volume data (init, delta)
+; AR2 points to the already mixed samples (s32)
+; AR3 points to where the output should be stored (s32)
+;
+; Returns:
+; AX0.L is the value of the last sample
+; AX1.H is the first address after the output
+mix_add:
+    lrri $AX1.L, @$AR1
+    bloopi #32, ____mix_add_end_loop+#IROM_BASE
+        lrri $AC0.M, @$AR2
+        lrri $AC0.L, @$AR2
+        lsl16 $ACC0
+        lrri $AX0.H, @$AR0
+        mulx $AX0.H, $AX1.L
+        addp $ACC0
+        asr16 $ACC0
+        srri @$AR3, $AC0.M
+____mix_add_end_loop:
+        srri @$AR3, $AC0.L
+    movp $ACC0
+    mrr $AX0.L, $AC0.M
+    mrr $AX1.H, $AR3
+    ret
+
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+
+; 8282
+mix_two_add_ramp:
+    call mix_add_ramp+#IROM_BASE
+    mrr $AR0, $IX0
+    mrr $AR2, $IX1
+    mrr $IX1, $AX0.L
+    call mix_add_ramp+#IROM_BASE
+    mrr $AX1.H, $AX0.L
+    mrr $AX0.L, $IX1
+    ret
+
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+    nop
+
+; 845d
+mix_add_ramp:
+    clr $ACC0
+    clr $ACC1
+    lrri $AC0.L, @$AR1
+    lrrd $AC1.L, @$AR1
+    mrr $IX2, $AR3
+
+    bloopi #32, ____mix_add_ramp_end_ramp+#IROM_BASE
+        srri @$AR3, $AC0.L
+____mix_add_ramp_end_ramp:
+        add $ACC0, $ACC1
+
+    srri @$AR1, $AC0.L
+    iar $AR1
+    mrr $IX3, $AR1
+    mrr $AR1, $IX2
+    mrr $AR3, $AR2
+
+    bloopi #32, ____mix_add_ramp_end_loop+#IROM_BASE
+        lrri $AC0.M, @$AR2
+        lrri $AC0.L, @$AR2
+        lsl16 $ACC0
+        lrri $AX0.H, @$AR0
+        lrri $AX1.L, @$AR1
+        mulx $AX0.H, $AX1.L
+        addp $ACC0
+        asr16 $ACC0
+        srri @$AR3, $AC0.M
+____mix_add_ramp_end_loop:
+        srri @$AR3, $AC0.L
+    movp $ACC0
+    mrr $AX0.L, $AC0.M
+    mrr $AX1.H, $AR3
+    mrr $AR1, $IX3
+    mrr $AR3, $IX2
+    ret
diff --git a/docs/DSP/free_dsp_rom/dsp_rom_readme.txt b/docs/DSP/free_dsp_rom/dsp_rom_readme.txt
new file mode 100644
index 0000000000..bcaa2eee43
--- /dev/null
+++ b/docs/DSP/free_dsp_rom/dsp_rom_readme.txt
@@ -0,0 +1,28 @@
+Legal GC/WII DSP IROM replacement (v0.2)
+-------------------------------------------------------
+
+- coef: crafted to use a linear interpolation when resampling (instead of
+  having a real 4 TAP FIR filter)
+- irom: added all the mixing functions, some functions not used by AX/Zelda are
+  still missing
+
+Should work with all AX, AXWii and Zelda UCode games. Card/IPL/GBA are most
+likely still broken with it and require a real DSP ROM.
+
+delroth
+16/march/2013
+
+Legal GC/WII DSP IROM replacement (v0.1)
+-------------------------------------------------------
+- coef: fake (zeroes)
+- irom: reversed and rewrote ucode loading/reset part, everything else is missing
+
+Good enough for Zelda ucode games (and maybe some AX too):
+- WII: SMG 1/2, Pikmin 1/2 WII, Zelda TP WII, Donkey Kong Jungle Beat (WII), ... 
+- GC: Mario Kart Double Dash, Luigi Mansion, Super Mario Sunshine, Pikmin 1/2, Zelda WW, Zelda TP, ...
+
+Basically... If game is not using coef and irom mixing functions it will work ok.
+Dolphin emulator will report wrong CRCs, but it will work ok with mentioned games.
+
+LM
+31/july/2011