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e4490faa2e
The working principle is similar as before with x86, but instead of outputting .asm, it outputs .wat. This can be compiled into .wasm by using the wat2wasm assembler.
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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