forked from len0rd/rockbox
Resort operands in mul/smull/mla/smlal to use D[] as second multiplication operand. Additionally do not pre-scale D[] for the 64 Bit precision synthesizer. Through this the 64 Bit multiplication is speed up by 1.5MHz without loss of precision.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17719 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Andree Buschmann
parent
95cd24d5a2
commit
c0951d95b3
2 changed files with 73 additions and 63 deletions
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@ -53,10 +53,17 @@
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#define MPC_V_PRESHIFT(X) MPC_SHR_RND(X, 12)
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// in this configuration a post-shift by >>1 is needed after synthesis
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#else
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#if defined(CPU_ARM)
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// do not up-scale D-values to achieve higher speed in smull/mlal
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// operations. saves ~14/8 = 1.75 cycles per multiplication
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#define D(value) (value)
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// in this configuration a post-shift by >>16 is needed after synthesis
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#else
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// saturate to +/- 2^31 (= value << (31-17)), D-values are +/- 2^17
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#define D(value) (value << (14))
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#endif
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// do not perform pre-shift
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#define MPC_V_PRESHIFT(X) (X)
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#endif
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@ -26,7 +26,8 @@
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*
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* 2nd step within synthesis filter. Does the dewindowing.
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* 32=32x32 multiplies (OPTIMIZE_FOR_SPEED)
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* Uses pre-shifted V[] and D[] values.
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* Uses pre-shifted V[] and D[] values. D[] will always be the second operand
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* of mul/mla to achieve higher speed as D[] has lower amplitude than V[].
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****************************************************************************/
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#if defined(OPTIMIZE_FOR_SPEED)
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.align 2
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@ -42,40 +43,40 @@ mpc_decoder_windowing_D:
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mov lr, #32
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.loop32:
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ldmia r2!, { r3-r10 } /* load first 8 window coefficients */
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ldmia r2!, { r3-r10 } /* load D[00..07] */
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ldr r11, [r1] /* 0 */
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mul r12, r3, r11
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mul r12, r11, r3
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ldr r11, [r1, #96*4] /* 1 */
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mla r12, r4, r11, r12
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mla r12, r11, r4, r12
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ldr r11, [r1, #128*4] /* 2 */
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mla r12, r5, r11, r12
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mla r12, r11, r5, r12
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ldr r11, [r1, #224*4] /* 3 */
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mla r12, r6, r11, r12
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mla r12, r11, r6, r12
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ldr r11, [r1, #256*4] /* 4 */
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mla r12, r7, r11, r12
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mla r12, r11, r7, r12
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ldr r11, [r1, #352*4] /* 5 */
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mla r12, r8, r11, r12
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mla r12, r11, r8, r12
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ldr r11, [r1, #384*4] /* 6 */
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mla r12, r9, r11, r12
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mla r12, r11, r9, r12
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ldr r11, [r1, #480*4] /* 7 */
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mla r12, r10, r11, r12
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ldmia r2!, { r3-r10 } /* load last 8 window coefficients */
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mla r12, r11, r10, r12
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ldmia r2!, { r3-r10 } /* load D[08..15] */
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ldr r11, [r1, #512*4] /* 8 */
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mla r12, r3, r11, r12
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mla r12, r11, r3, r12
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ldr r11, [r1, #608*4] /* 9 */
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mla r12, r4, r11, r12
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mla r12, r11, r4, r12
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ldr r11, [r1, #640*4] /* 10 */
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mla r12, r5, r11, r12
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mla r12, r11, r5, r12
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ldr r11, [r1, #736*4] /* 11 */
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mla r12, r6, r11, r12
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mla r12, r11, r6, r12
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ldr r11, [r1, #768*4] /* 12 */
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mla r12, r7, r11, r12
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mla r12, r11, r7, r12
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ldr r11, [r1, #864*4] /* 13 */
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mla r12, r8, r11, r12
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mla r12, r11, r8, r12
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ldr r11, [r1, #896*4] /* 14 */
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mla r12, r9, r11, r12
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mla r12, r11, r9, r12
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ldr r11, [r1, #992*4] /* 15 */
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mla r12, r10, r11, r12
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mla r12, r11, r10, r12
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mov r12, r12, asr #1 /* post shift to compensate for pre-shifting */
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str r12, [r0], #4 /* store Data */
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add r1, r1, #4 /* V++ */
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@ -92,9 +93,8 @@ mpc_decoder_windowing_D:
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*
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* 2nd step within synthesis filter. Does the dewindowing.
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* 64=32x32 multiplies
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* Drops lo-part of 64bit multiply results and will therefor loose 1 bit
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* accuracy. The decoder output is binary identical as this imprecision is
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* far below the output's 16bit resolution.
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* Uses un-shifted D[]-values. D[] will always be the second operand of
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* smull/smlal to achieve higher speed as D[] has lower amplitude than V[].
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****************************************************************************/
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.align 2
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.global mpc_decoder_windowing_D
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@ -105,52 +105,55 @@ mpc_decoder_windowing_D:
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/* r2 = D[] */
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/* lr = counter */
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stmfd sp!, {r4-r12, lr}
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stmfd sp!, {r4-r9, lr}
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mov lr, #32
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.loop32:
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ldmia r2!, { r3-r10 } /* load first 8 window coefficients */
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ldr r11, [r1] /* 0 */
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smull r11, r12, r3, r11
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ldr r11, [r1, #96*4] /* 1 */
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smlal r11, r12, r4, r11
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ldr r11, [r1, #128*4] /* 2 */
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smlal r11, r12, r5, r11
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ldr r11, [r1, #224*4] /* 3 */
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smlal r11, r12, r6, r11
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ldr r11, [r1, #256*4] /* 4 */
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smlal r11, r12, r7, r11
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ldr r11, [r1, #352*4] /* 5 */
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smlal r11, r12, r8, r11
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ldr r11, [r1, #384*4] /* 6 */
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smlal r11, r12, r9, r11
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ldr r11, [r1, #480*4] /* 7 */
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smlal r11, r12, r10, r11
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ldmia r2!, { r3-r10 } /* load last 8 window coefficients */
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ldr r11, [r1, #512*4] /* 8 */
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smlal r11, r12, r3, r11
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ldr r11, [r1, #608*4] /* 9 */
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smlal r11, r12, r4, r11
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ldr r11, [r1, #640*4] /* 10 */
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smlal r11, r12, r5, r11
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ldr r11, [r1, #736*4] /* 11 */
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smlal r11, r12, r6, r11
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ldr r11, [r1, #768*4] /* 12 */
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smlal r11, r12, r7, r11
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ldr r11, [r1, #864*4] /* 13 */
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smlal r11, r12, r8, r11
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ldr r11, [r1, #896*4] /* 14 */
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smlal r11, r12, r9, r11
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ldr r11, [r1, #992*4] /* 15 */
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smlal r11, r12, r10, r11
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mov r4, r12, lsl #2 /* get result from hi-part, loose 2 bits */
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str r4, [r0], #4 /* store Data */
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ldmia r2!, { r3-r6 } /* load D[00..03] */
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ldr r7, [r1] /* 0 */
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smull r8, r9, r7, r3
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ldr r7, [r1, #96*4] /* 1 */
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smlal r8, r9, r7, r4
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ldr r7, [r1, #128*4] /* 2 */
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smlal r8, r9, r7, r5
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ldr r7, [r1, #224*4] /* 3 */
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smlal r8, r9, r7, r6
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ldmia r2!, { r3-r6 } /* load D[04..07] */
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ldr r7, [r1, #256*4] /* 4 */
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smlal r8, r9, r7, r3
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ldr r7, [r1, #352*4] /* 5 */
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smlal r8, r9, r7, r4
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ldr r7, [r1, #384*4] /* 6 */
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smlal r8, r9, r7, r5
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ldr r7, [r1, #480*4] /* 7 */
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smlal r8, r9, r7, r6
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ldmia r2!, { r3-r6 } /* load D[08..11] */
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ldr r7, [r1, #512*4] /* 8 */
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smlal r8, r9, r7, r3
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ldr r7, [r1, #608*4] /* 9 */
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smlal r8, r9, r7, r4
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ldr r7, [r1, #640*4] /* 10 */
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smlal r8, r9, r7, r5
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ldr r7, [r1, #736*4] /* 11 */
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smlal r8, r9, r7, r6
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ldmia r2!, { r3-r6 } /* load D[12..15] */
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ldr r7, [r1, #768*4] /* 12 */
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smlal r8, r9, r7, r3
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ldr r7, [r1, #864*4] /* 13 */
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smlal r8, r9, r7, r4
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ldr r7, [r1, #896*4] /* 14 */
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smlal r8, r9, r7, r5
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ldr r7, [r1, #992*4] /* 15 */
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smlal r8, r9, r7, r6
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mov r8, r8, lsr #16
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orr r8, r8, r9, lsl #16 /* (lo>>16) || (hi<<16) */
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str r8, [r0], #4 /* store Data */
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add r1, r1, #4 /* V++ */
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subs lr, lr, #1
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bgt .loop32
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ldmfd sp!, {r4-r12, pc}
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ldmfd sp!, {r4-r9, pc}
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.mpc_dewindowing_end:
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.size mpc_decoder_windowing_D,.mpc_dewindowing_end-mpc_decoder_windowing_D
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#endif
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