Change loadnote to load values from [-1,1], to allow using notes for both positive and negative modulations.

Also change SPEED to take this change into account.

src/opcodes/arithmetic.asm

@@ -65,7 +65,7 @@ su_op_addp_mono:
 %endif
 
 ;-------------------------------------------------------------------------------
-;   LOADNOTE opcode: load the current note, scaled to [0,1]
+;   LOADNOTE opcode: load the current note, scaled to [-1,1]
 ;-------------------------------------------------------------------------------
 ;   Mono:   (empty) -> n, where n is the note
 ;   Stereo: (empty) -> n n
@@ -80,6 +80,8 @@ su_op_loadnote_mono:
 %endif
     fild    dword [INP-su_voice.inputs+su_voice.note]
  do fmul    dword [,c_i128,]
+ do fsub    dword [,c_0_5,]              ; s-.5
+    fadd    st0, st0                     ; 2*s-1
     ret
 
 %endif

src/opcodes/flowcontrol.asm

@@ -47,8 +47,6 @@ su_op_advance_finish:
 SECT_TEXT(suspeed)
 
 EXPORT MANGLE_FUNC(su_op_speed,0)
- do fsub    dword [,c_0_5,]              ; s-.5
-    fadd    st0, st0                     ; 2*s-1
  do fmul    dword [,c_bpmscale,]         ; (2*s-1)*64/24, let's call this p from now on
     call    MANGLE_FUNC(su_power,0)      ; 2^p, this is how many ticks we should be taking
     fld1                                 ; 1 2^p