fix bug in SSE version of ...autocorrelation...

diff --git a/src/libFLAC/i386/lpc_asm.s b/src/libFLAC/i386/lpc_asm.s
index 0bf46172cbe0ab5a6f026d0a343a0213e8dfc698..53c94603cb6c87b1aeadc011aed8d9ac4b1f5bec 100644 (file)
--- a/src/libFLAC/i386/lpc_asm.s
+++ b/src/libFLAC/i386/lpc_asm.s
@@ -57,10 +57,10 @@ cglobal FLAC__lpc_restore_signal_asm_i386_mmx
        ALIGN 16
 cident FLAC__lpc_compute_autocorrelation_asm_i386
 
-       ; esp + 32 == autoc[]
-       ; esp + 28 == lag
-       ; esp + 24 == data_len
-       ; esp + 20 == data[]
+       ;[esp + 32] == autoc[]
+       ;[esp + 28] == lag
+       ;[esp + 24] == data_len
+       ;[esp + 20] == data[]
 
        push    ebp
        push    ebx
@@ -208,10 +208,10 @@ cident FLAC__lpc_compute_autocorrelation_asm_i386
        ALIGN 16
 cident FLAC__lpc_compute_autocorrelation_asm_i386_sse
 
-       ; esp + 16 == autoc[]
-       ; esp + 12 == lag
-       ; esp + 8 == data_len
-       ; esp + 4 == data[]
+       ;[esp + 16] == autoc[]
+       ;[esp + 12] == lag
+       ;[esp + 8] == data_len
+       ;[esp + 4] == data[]
 
        ;       for(coeff = 0; coeff < lag; coeff++)
        ;               autoc[coeff] = 0.0;
@@ -227,45 +227,38 @@ cident FLAC__lpc_compute_autocorrelation_asm_i386_sse
        shufps  xmm0, xmm0, 0                   ; xmm0 = data[0],data[0],data[0],data[0]
        movaps  xmm1, xmm0                      ; xmm1 = data[0],data[0],data[0],data[0]
        xorps   xmm3, xmm3                      ; xmm3 = 0,0,0,0
-.warmup:                                       ; xmm3:xmm2 = data[sample-[7..0]]
-       movaps  xmm4, xmm0
-       movaps  xmm5, xmm1                      ; xmm5:xmm4 = xmm1:xmm0 = data[sample]*8
-       mulps   xmm4, xmm2
-       mulps   xmm5, xmm3                      ; xmm5:xmm4 = xmm1:xmm0 * xmm3:xmm2
-       addps   xmm6, xmm4
-       addps   xmm7, xmm5                      ; xmm7:xmm6 += xmm1:xmm0 * xmm3:xmm2
+.warmup:                                       ; xmm3:xmm2 == data[sample-7],data[sample-6],...,data[sample]
+       mulps   xmm0, xmm2
+       mulps   xmm1, xmm3                      ; xmm5:xmm4 = xmm1:xmm0 * xmm3:xmm2
+       addps   xmm6, xmm0
+       addps   xmm7, xmm1                      ; xmm7:xmm6 += xmm1:xmm0 * xmm3:xmm2
        dec     edx
        ;* there's no need to even check for this because we know that lag == 8
        ;* and data_len >= lag, so our 1-sample warmup cannot finish the loop
        ; jz    .loop_end
        ALIGN 16
 .loop_8:
-       ; read the next sample
+       ; start by reading the next sample
        movss   xmm0, [eax]                     ; xmm0 = 0,0,0,data[sample]
-       add     eax, 4
-       shufps  xmm0, xmm0, 0                   ; xmm0 = data[sample],data[sample],data[sample],data[sample]
-       movaps  xmm1, xmm0                      ; xmm1 = data[sample],data[sample],data[sample],data[sample]
-       ; now shift the lagged samples
-       movaps  xmm4, xmm2
-       movaps  xmm5, xmm3
-       shufps  xmm2, xmm4, 93h                 ; 93h=2-1-0-3 => xmm2 gets rotated left by one float
-       shufps  xmm3, xmm5, 93h                 ; 93h=2-1-0-3 => xmm3 gets rotated left by one float
-       movss   xmm3, xmm2
-       movss   xmm2, xmm0
-
-       movaps  xmm4, xmm0
-       movaps  xmm5, xmm1                      ; xmm5:xmm4 = xmm1:xmm0 = data[sample]*8
-       mulps   xmm4, xmm2
-       mulps   xmm5, xmm3                      ; xmm5:xmm4 = xmm1:xmm0 * xmm3:xmm2
-       addps   xmm6, xmm4
-       addps   xmm7, xmm5                      ; xmm7:xmm6 += xmm1:xmm0 * xmm3:xmm2
+       ; here we reorder the instructions; see the (#) indexes for a logical order
+       shufps  xmm2, xmm2, 93h                 ; (3) 93h=2-1-0-3 => xmm2 gets rotated left by one float
+       add     eax, 4                          ; (0)
+       shufps  xmm3, xmm3, 93h                 ; (4) 93h=2-1-0-3 => xmm3 gets rotated left by one float
+       shufps  xmm0, xmm0, 0                   ; (1) xmm0 = data[sample],data[sample],data[sample],data[sample]
+       movss   xmm3, xmm2                      ; (5)
+       movaps  xmm1, xmm0                      ; (2) xmm1 = data[sample],data[sample],data[sample],data[sample]
+       movss   xmm2, xmm0                      ; (6)
+       mulps   xmm1, xmm3                      ; (8)
+       mulps   xmm0, xmm2                      ; (7) xmm5:xmm4 = xmm1:xmm0 * xmm3:xmm2
+       addps   xmm7, xmm1                      ; (10)
+       addps   xmm6, xmm0                      ; (9) xmm7:xmm6 += xmm1:xmm0 * xmm3:xmm2
        dec     edx
        jnz     .loop_8
 .loop_end:
        ; store autoc
        mov     edx, [esp + 16]                 ; edx == autoc
-       movups  xmm6, [edx]
-       movups  xmm7, [edx + 4]
+       movups  [edx], xmm6
+       movups  [edx + 4], xmm7
 
 .end:
        ret