In rust this looks rather painful. Might I suggest trying this in Julia, might be a good comparison of performance, ease of use, and readability. Julia does a very nice job of compiling directly to SIMD instruction and lets you inspect the low level code generated.

inline function sin9_shaper(x) c0 = 6.28308759 c1 = -41.33318707 c2 = 81.39900205 c3 = -74.66884436 c4 = 33.15324345

    a = abs(x - round(x)) - 0.25
    a2 = a * a
    ((((a2 * c4 + c3) * a2 + c2) * a2 + c1) * a2 + c0) * a

end

function gen_sinwave(freq, init=0.0, step=0.1) wave = [sin9_shaper(x) for x = init:step:freq] end

julia> @code_native gen_sinwave(1113.0); .section __TEXT,__text,regular,pure_instructions ; Function gen_sinwave { ; Location: REPL[60]:2 pushl %ebx decl %eax subl $48, %esp vmovaps %xmm0, %xmm2 ; Function gen_sinwave; { ; Location: REPL[60]:2 decl %eax movl $769501344, %eax ## imm = 0x2DDDA8A0 addl %eax, (%eax) addb %al, (%eax) decl %eax movl $773805120, %ecx ## imm = 0x2E1F5440 addl %eax, (%eax) addb %al, (%eax) vmovsd (%ecx), %xmm1 ## xmm1 = mem[0],zero decl %eax movl %esp, %ebx vxorps %xmm0, %xmm0, %xmm0 decl %eax movl %ebx, %edi calll %eax decl %eax movl $769544608, %eax ## imm = 0x2DDE51A0 addl %eax, (%eax) addb %al, (%eax) decl %eax movl %ebx, %edi calll %eax ;} decl %eax addl $48, %esp popl %ebx retl nopw %cs:(%eax,%eax) ;}

end # module