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.align 4
.text
.globl DecodeBlockAsm
/*
;Bit-Rate Expand Waveform
;
;Desc:
; Decompresses a 9-byte bit-rate reduced block into 16 16-bit samples.
; This procedure is designed to be recursively called to decompress a series of blocks.
;In:
; R0=ESI-> Sample Block
; R1=EDI -> Output buffer
; R2=EDX =3D Last sample of previous block (32-bit)
; R3=EBX =3D Next to last sample (sign extended from 16-bits)
;Out:
; R0=ESI -> Next Block
; R1=EDI -> After last sample
; R2=EDX =3D Last sample (32-bit)
; R3=EBX =3D Next to last sample (16-bit)
;Destroys:
; R4=EAX
*/
@ void DecodeBlockAsm2 (int8 *, int16 *, int32 *, int32 *);
@ DecodeBlockAsm2 (compressed, raw, &ch->previous [0], &ch->previous [1]);
.align 4
DecodeBlockAsm:
stmfd sp!, {r2, r3, r4, r5, r6, r7}
LDRB R4,[R0],#1
LDR R2,[R2]
LDR R3,[R3]
CMP R4,#0xD0
MOVHS R5,#0
rsblo r5, r4, #0xcf
MOVLO R5,R5,LSR #4
MOV R6,#8
TST R4,#0xC
BEQ Method0
TST R4,#0x8
BEQ Method1
TST R4,#0x4
BEQ Method2
B Method3 @ ;Must use method 3
/*
ALIGN 16
;[Smp] ----------------------------------*/
Method0:
ADD R5,R5,#16
.macro MMethod0
.endm
Method0loop:
@ two in a go
LDRB R4,[R0],#1
ldrb r7,[r0],#1
MOV R2,R4,LSL #(28)
MOV R4,R4,LSL #(24)
BIC R4,R4,#0x0F000000
MOV R4,R4,ASR R5
MOV R2,R2,ASR R5
STRH R4,[R1],#2
STRH R2,[R1],#2
@SUBS R6,R6,#1
@beq Exit0
@LDRB R4,[R0],#1
MOV R2,R7,LSL #(28)
MOV R4,R7,LSL #(24)
BIC R4,R4,#0x0F000000
MOV R4,R4,ASR R5
MOV R2,R2,ASR R5
STRH R4,[R1],#2
STRH R2,[R1],#2
@SUBS R6,R6,#1
subs r6, r6, #2
BNE Method0loop
mov r3, r4
ldmfd sp!, {r0, r1, r4, r5, r6, r7}
STR R2,[R0]
STR R3,[R1]
bx lr
@ ALIGN 16
@ ;[Delta]+[Smp-1](15/16) -----------------
Method1:
ADD R7,R5,#16
Method1loop:
LDRSB R3,[R0]
BIC R3,R3,#0xF
MOV R3,R3,LSL #8
MOV R3,R3,ASR R5
MOV R4,R2,LSL #16
ADD R3,R3,R4,ASR #16
SUB R3,R3,R4,ASR #20
STRH R3,[R1],#2
LDRSB R2,[R0],#1
MOV R2,R2,LSL #(12+16)
MOV R2,R2,ASR R7
MOV R4,R3,LSL #16
ADD R2,R2,R4,ASR #16
SUB R2,R2,R4,ASR #20
STRH R2,[R1],#2
SUBS R6,R6,#1
BNE Method1loop
MOV R3,R3,LSL #16
MOV R3,R3,ASR #16
ldmfd sp!, {r0, r1, r4, r5, r6, r7}
STR R2,[R0]
STR R3,[R1]
bx lr
@ ;[Delta]+[Smp-1](61/32)-[Smp-2](30/32) --
Method2:
ADD R7,R5,#16
Method2loop:
LDRSB R4,[R0], #1
mov r12, r4
BIC R4,R4,#0xF
MOV R4,R4,LSL #8
MOV R4,R4,ASR R5
SUB R4,R4,R3
ADD R4,R4,R3,ASR #4
MOV R3,R2
BIC R2,R2,#3
ADD R4,R4,R2,LSL #1
SUB R4,R4,R2,ASR #4
SUB R4,R4,R2,ASR #5
STRH R4,[R1],#2
MOV R2,R12,LSL #(12+16)
MOV R2,R2,ASR R7
SUB R2,R2,R3
ADD R2,R2,R3,ASR #4
MOV R3,R4
BIC R4,R4,#3
ADD R2,R2,R4,LSL #1
SUB R2,R2,R4,ASR #4
SUB R2,R2,R4,ASR #5
STRH R2,[R1],#2
SUBS R6,R6,#1
BNE Method2loop
ldmfd sp!, {r0, r1, r4, r5, r6, r7}
STR R2,[R0]
STR R3,[R1]
bx lr
Method3:
ADD R7,R5,#16
Method3loop:
LDRSB R4,[R0], #1
mov r12, r4
BIC R4,R4,#0xF
MOV R4,R4,LSL #8
MOV R4,R4,ASR R5
@ ;Subtract 13/16 of second sample -----
SUB R4,R4,R3
ADD R4,R4,R3,ASR #3
ADD R4,R4,R3,ASR #4
MOV R3,R2
@ ;Add 115/64 of last sample -----------
BIC R2,R2,#3
ADD R4,R4,R2,LSL #1
SUB R4,R4,R2,ASR #3
SUB R4,R4,R2,ASR #4
SUB R4,R4,R2,ASR #6
STRH R4,[R1],#2
MOV R2,R12,LSL #(12+16)
MOV R2,R2,ASR R7
SUB R2,R2,R3
ADD R2,R2,R3,ASR #3
ADD R2,R2,R3,ASR #4
MOV R3,R4
BIC R4,R4,#3
ADD R2,R2,R4,LSL #1
SUB R2,R2,R4,ASR #3
SUB R2,R2,R4,ASR #4
SUB R2,R2,R4,ASR #6
STRH R4,[R1],#2
SUBS R6,R6,#1
BNE Method3loop
ldmfd sp!, {r0, r1, r4, r5, r6, r7}
STR R2,[R0]
STR R3,[R1]
bx lr
.pool
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