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d0bd877b3f
There is no more plain .asms, both library & player are created from the templates using go text/template package.
24 lines
1.3 KiB
NASM
24 lines
1.3 KiB
NASM
{{- if .HasOp "speed" -}}
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;-------------------------------------------------------------------------------
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; SPEED opcode: modulate the speed (bpm) of the song based on ST0
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;-------------------------------------------------------------------------------
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; Mono: adds or subtracts the ticks, a value of 0.5 is neutral & will7
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; result in no speed change.
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; There is no STEREO version.
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;-------------------------------------------------------------------------------
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{{.Func "su_op_speed" "Opcode"}}
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{{- .Float 2.206896551724138 | .Prepare | indent 4}}
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fmul dword [{{.Float 2.206896551724138 | .Use}}] ; (2*s-1)*64/24, let's call this p from now on
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{{.Call "su_power"}}
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fld1 ; 1 2^p
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fsubp st1, st0 ; 2^p-1, the player is advancing 1 tick by its own
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fadd dword [{{.WRK}}] ; t+2^p-1, t is the remainder from previous rounds as ticks have to be rounded to 1
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push {{.AX}}
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fist dword [{{.SP}}] ; Main stack: k=int(t+2^p-1)
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fisub dword [{{.SP}}] ; t+2^p-1-k, the remainder
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pop {{.AX}}
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add dword [{{.Stack "Sample"}}], eax ; add the whole ticks to row tick count
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fstp dword [{{.WRK}}] ; save the remainder for future
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ret
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{{end}}
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