quake: clean up asm mixer
Fixes my ugly formatting.
This commit is contained in:
Franklin Wei
parent
01cccaf2d2
commit
c0cc9aa9e8
1 changed files with 46 additions and 63 deletions
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@ -19,9 +19,11 @@
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*
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***************************************************************************/
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/** Sound mixing code for ARM. **/
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/* Takes 8-bit mono audio and outputs stereo 16-bit samples.
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* stereo volumes are passed as arguments.
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/*
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* Sound mixing code for ARM.
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*
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* Takes an array of 8-bit mono audio and outputs stereo 16-bit
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* samples. Stereo volumes are passed as arguments r0 and r1.
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*
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* Bear with me. This is my first ARM assembly, ever.
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*/
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@ -33,93 +35,74 @@
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#if defined(__ARM_ARCH_5TEJ__)
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SND_PaintChannelFrom8:
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// r0: int true_lvol
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// r1: int true_rvol
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// r2: char *sfx
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// r3: int count
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;; r0: int true_lvol
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;; r1: int true_rvol
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;; r2: char *sfx
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;; r3: int count
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stmfd sp!, {r4, r5, r6, r7, r8, sl}
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ldr ip, =paintbuffer
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ldr ip, [ip]
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mov r0, r0, asl #16 // pre-scale both volumes by 2^16
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mov r0, r0, asl #16 ; prescale by 2^16
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mov r1, r1, asl #16
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sub r3, r3, #1 // we'll count backwards
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// sl = 0xffff0000
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ldrh sl, =0xffff
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sub r3, r3, #1 ; count backwards
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.loop:
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ldrsb r4, [r2, r3] // load *sfx[i] -> r4
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ldrh sl, =0xffff ; halfword mask
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// keep endianness in mind here
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// buffer looks like [left_0, left_1, right_0, right_1] in memory
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// but it is loaded as [right1, right0, left1, left0] to registers
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ldr r8, [ip, r3, lsl #2] // load paintbuffer[0:1] = RIGHTCHANNEL:LEFTCHANNEL
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1:
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ldrsb r4, [r2, r3] ; load input sample
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ldr r8, [ip, r3, lsl #2] ; load output sample pair from paintbuffer
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; (left:right in memory -> right:left in register)
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;; right channel (high half)
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mul r5, r4, r1 ; scaledright = sfx[i] * (true_rvol << 16) -- bottom half is zero
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qadd r7, r5, r8 ; right = scaledright + right (in high half of word)
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bic r7, r7, sl ; zero bottom half of r7
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// handle high half (right channel) first
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mul r5, r4, r1 // SCALEDRIGHT = SFXI * (true_rvol << 16) -- bottom half is zero
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;; left channel (low half)
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mul r5, r4, r0 ; scaledleft = sfx[i] * (true_rvol << 16)
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mov r8, r8, lsl #16 ; extract original left channel from paintbuffer
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qadd r8, r5, r8 ; left = scaledleft + left
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// r7 holds right channel in high half (dirty bottom half)
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qadd r7, r5, r8 // RIGHTCHANORIG = SCALEDRIGHT + RIGHTCHANORIG (high half)
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bic r7, r7, sl // zero bottom bits of r7
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// trash r5, r6 and handle left channel
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mul r5, r4, r0 // SCALEDLEFT = SFXI * (true_rvol << 16)
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mov r8, r8, lsl #16 // extract original left channel from paintbuffer
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// r8 holds left channel in high half with zero bottom half
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qadd r8, r5, r8
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// combine the two 16-bit samples in r7 as 32-bit [left:right]
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// (use lsr to not sign-extend the lower half)
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orr r7, r7, r8, lsr #16
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str r7, [ip, r3, lsl #2] // write 32-bit to paintbuffer
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orr r7, r7, r8, lsr #16 ; combine right:left in r7
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str r7, [ip, r3, lsl #2] ; write right:left to output buffer
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subs r3, r3, #1
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bgt .loop // must use instead of bne because of the corner case count=1
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bgt 1b ; must use bgt instead of bne in case count=1
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ldmfd sp!, {r4, r5, r6, r7, r8, sl}
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bx lr
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#elif defined(__ARM_ARCH_6__) // ARMv6 with QADD16 (disabled)
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#elif defined(__ARM_ARCH_6__) ; ARMv6 with QADD16 (disabled)
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SND_PaintChannelFrom8:
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// r0: int true_lvol
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// r1: int true_rvol
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// r2: char *sfx
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// r3: int count
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;; r0: int true_lvol
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;; r1: int true_rvol
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;; r2: char *sfx
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;; r3: int count
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stmfd sp!, {r4, r5, r6, r7}
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ldr ip, =paintbuffer
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ldr ip, [ip]
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sub r3, r3, #1 // we'll count backwards
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.loop:
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ldrsb r4, [r2, r3] // load *sfx[i] -> r4
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ldr ip, [ip] ; load paintbuffer address
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sub r3, r3, #1 ; we'll count backwards
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1:
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ldrsb r4, [r2, r3] ; load sfx[i] -> r4
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ldr r7, [ip, r3, lsl #2] ; load old sample pair
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// keep endianness in mind here
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// buffer looks like [left_0, left_1, right_0, right_1] in memory
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// but it is loaded as [right1, right0, left1, left0] to registers
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ldr r7, [ip, r3, lsl #2] // load paintbuffer[0:1] = RIGHTCHANNEL:LEFTCHANNEL
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mul r5, r4, r1 ; SCALEDRIGHT = SFXI * true_rvol
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mul r6, r4, r0 ; SCALEDLEFT = SFXI * true_rvol
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// handle high half (right channel) first
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mul r5, r4, r1 // SCALEDRIGHT = SFXI * true_rvol
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mul r6, r4, r0 // SCALEDLEFT = SFXI * true_rvol
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orr r6, r6, r5, lsl #16 ; combine samples as 32-bit
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orr r6, r6, r5, lsl #16
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qadd16 r6, r6, r7 ; parallel 16-bit add
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qadd16 r6, r6, r7
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str r6, [ip, r3, lsl #2] // write 32-bit to paintbuffer
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str r6, [ip, r3, lsl #2] ; write 32-bit to paintbuffer
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subs r3, r3, #1
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bne .loop
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bgt 1b
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ldmfd sp!, {r4, r5, r6, r7}
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