Fast cases for short •rand.Deal𝕩
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@ -425,52 +425,68 @@ B rand_range_c2(B t, B w, B x) {
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return taga(r);
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}
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extern Arr* bitUD[3]; // from fns.c
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extern B bit2x[2];
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B rand_deal_c1(B t, B x) {
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i32 xi = o2i(x);
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if (RARE(xi<0)) thrM("(rand).Deal: Argument cannot be negative");
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if (xi==0) return emptyIVec();
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RAND_START;
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i32* rp; B r = m_i32arrv(&rp, xi);
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// MergeShuffle
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usz sh = 0;
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usz thr = 1<<18;
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while ((xi >> sh) > thr) sh++;
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usz q = 1 << sh;
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u64 n = xi;
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for (usz p = 0, i = 0; p < q; p++) {
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usz e = (n*(p+1)) >> sh;
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for (usz k = i; k < e; k++) rp[k] = k;
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for (; i < e; i++) {
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usz j = wy2u0k(wyrand(&seed), e-i) + i;
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usz c=rp[j]; rp[j]=rp[i]; rp[i]=c;
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}
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if (RARE(xi<=1)) {
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if (xi<0) thrM("(rand).Deal: Argument cannot be negative");
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return xi==0? emptyIVec() : taga(ptr_inc(bitUD[xi]));
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}
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for (usz w = 1; w < q; w <<= 1) {
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usz i = 0;
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for (usz p = 0; p < q; p += 2*w) {
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usz t = i;
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usz j = (n*(p + w)) >> sh;
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usz e = (n*(p + 2*w)) >> sh;
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for (usz i0 = i; ; i0 += 64) {
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for (u64 r = wyrand(&seed); r; r&=r-1) {
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i = i0 + CTZ(r);
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if (i > j) { i=j; goto tail; }
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if (j == e) goto tail;
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usz c=rp[j]; rp[j]=rp[i]; rp[i]=c;
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j++;
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}
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}
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tail:
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RAND_START;
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B r;
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if (xi == 2) {
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r = incG(bit2x[wyrand(&seed)&1]);
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} else if (LIKELY(xi <= 128)) {
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i8* rp; r = m_i8arrv(&rp, xi);
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for (usz i = 0; i < xi; i++) rp[i] = i;
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for (usz i = 0; i < xi-1; i++) {
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usz j = wy2u0k(wyrand(&seed), xi-i) + i;
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usz c=rp[j]; rp[j]=rp[i]; rp[i]=c;
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}
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} else {
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i32* rp; r = m_i32arrv(&rp, xi);
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// MergeShuffle
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usz sh = 0;
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usz thr = 1<<18;
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while ((xi >> sh) > thr) sh++;
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usz q = 1 << sh;
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u64 n = xi;
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for (usz p = 0, i = 0; p < q; p++) {
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usz e = (n*(p+1)) >> sh;
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for (usz k = i; k < e; k++) rp[k] = k;
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for (; i < e; i++) {
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usz j = wy2u0k(wyrand(&seed), 1+i-t) + t;
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usz j = wy2u0k(wyrand(&seed), e-i) + i;
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usz c=rp[j]; rp[j]=rp[i]; rp[i]=c;
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}
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}
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}
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for (usz w = 1; w < q; w <<= 1) {
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usz i = 0;
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for (usz p = 0; p < q; p += 2*w) {
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usz t = i;
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usz j = (n*(p + w)) >> sh;
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usz e = (n*(p + 2*w)) >> sh;
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for (usz i0 = i; ; i0 += 64) {
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for (u64 r = wyrand(&seed); r; r&=r-1) {
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i = i0 + CTZ(r);
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if (i > j) { i=j; goto tail; }
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if (j == e) goto tail;
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usz c=rp[j]; rp[j]=rp[i]; rp[i]=c;
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j++;
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}
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}
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tail:
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for (; i < e; i++) {
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usz j = wy2u0k(wyrand(&seed), 1+i-t) + t;
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usz c=rp[j]; rp[j]=rp[i]; rp[i]=c;
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}
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}
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}
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}
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RAND_END;
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return r;
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}
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@ -478,10 +494,11 @@ B rand_deal_c1(B t, B x) {
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B rand_deal_c2(B t, B w, B x) {
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i32 wi = o2i(w);
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i32 xi = o2i(x);
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if (RARE(wi<0)) thrM("(rand).Deal: 𝕨 cannot be negative");
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if (RARE(xi<0)) thrM("(rand).Deal: 𝕩 cannot be negative");
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if (RARE(wi>xi)) thrM("(rand).Deal: 𝕨 cannot exceed 𝕩");
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if (RARE(wi<0)) thrM("(rand).Deal: 𝕨 cannot be negative");
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if (wi==0) return emptyIVec();
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if (RARE(wi>xi)) thrM("(rand).Deal: 𝕨 cannot exceed 𝕩");
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if (wi==xi) return rand_deal_c1(t, x);
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B r;
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RAND_START;
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if (wi > xi/64) {
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