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2ad61ff6b2
The preprocessing is done sointu-cli and (almost) nothing is done by the NASM preprocessor anymore (some .strucs are still there. Now, sointu-cli loads the .yml song, defines bunch of macros (go functions / variables) and passes the struct to text/template parses. This a lot more powerful way to generate .asm code than trying to fight with the nasm preprocessor. At the moment, tests pass but the repository is a bit of monster, as the library is still compiled using the old approach. Go should generate the library also from the templates.
24 lines
1.3 KiB
NASM
24 lines
1.3 KiB
NASM
{{- if .Opcode "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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