add checks for l>0 on equal() impls

some Singeli `fn equal` paths already assumed such, this just makes the requirement properly checked for, benefited from, and documented

4 files changed, 7 insertions, 5 deletions

diff --git a/src/builtins/compare.c b/src/builtins/compare.c
index a8b5268f..f55831cf 100644
--- a/src/builtins/compare.c
+++ b/src/builtins/compare.c
@@ -107,13 +107,14 @@ u8 const eqFnData[] = { // for the main diagonal, amount to shift length by; oth
 #else
   #define F(X) equal_##X
   bool F(1_1)(void* w, void* x, u64 l, u64 d) {
+    assert(l>0);
     u64* wp = w; u64* xp = x;
     usz q = l/64;
     for (usz i=0; i<q; i++) if (wp[i] != xp[i]) return false;
     usz r = (-l)%64; return r==0 || (wp[q]^xp[q])<<r == 0;
   }
   #define DEF_EQ_U1(N, T) \
-    bool F(1_##N)(void* w, void* x, u64 l, u64 d) {                    \
+    bool F(1_##N)(void* w, void* x, u64 l, u64 d) { assert(l>0);       \
       if (d!=0) { void* t=w; w=x; x=t; }                               \
       u64* wp = w; T* xp = x;                                          \
       for (usz i=0; i<l; i++) if (bitp_get(wp,i)!=xp[i]) return false; \
@@ -127,7 +128,7 @@ u8 const eqFnData[] = { // for the main diagonal, amount to shift length by; oth
 
   #define DEF_EQ_I(NAME, S, T, INIT) \
     bool F(NAME)(void* w, void* x, u64 l, u64 d) {            \
-      INIT                                                    \
+      assert(l>0); INIT                                       \
       S* wp = w; T* xp = x;                                   \
       for (usz i=0; i<l; i++) if (wp[i]!=xp[i]) return false; \
       return true;                                            \
@@ -143,7 +144,7 @@ u8 const eqFnData[] = { // for the main diagonal, amount to shift length by; oth
   #undef DEF_EQ_I
   #undef DEF_EQ
 #endif
-bool notEq(void* a, void* b, u64 l, u64 data) { return false; }
+bool notEq(void* a, void* b, u64 l, u64 data) { assert(l>0); return false; }
 INIT_GLOBAL EqFn eqFns[] = {
   F(1_1),   F(1_8),    F(1_16),    F(1_32),    F(1_f64),   notEq,    notEq,     notEq,
   F(1_8),   F(8_8),    F(s8_16),   F(s8_32),   F(s8_f64),  notEq,    notEq,     notEq,
diff --git a/src/singeli/src/equal.singeli b/src/singeli/src/equal.singeli
index b80eb02d..3bdd7ff2 100644
--- a/src/singeli/src/equal.singeli
+++ b/src/singeli/src/equal.singeli
@@ -15,6 +15,7 @@ fn equal{W, X}(w:*void, x:*void, l:u64, d:u64) : u1 = {
   def vw = arch_defvw
   def bulk = vw / width{X}
   if (W!=X) if (d!=0) swap{w,x}
+  assert{l>0}
   
   if (W==u1) {
     if (X==u1) { # bitarr ≡ bitarr
diff --git a/src/singeli/src/mask.singeli b/src/singeli/src/mask.singeli
index d9979b7d..adc575e2 100644
--- a/src/singeli/src/mask.singeli
+++ b/src/singeli/src/mask.singeli
@@ -103,6 +103,7 @@ def maskedLoop{bulk} = maskedLoop{bulk,0}
 
 
 def maskedLoopPositive{bulk}{vars,begin==0,end:L,iter} = {
+  assert{end > 0}
   i:L = 0
   while(i < (end-1)/bulk) {
     mlExec{i, iter, vars, bulk, maskNone}
diff --git a/src/utils/calls.h b/src/utils/calls.h
index d38cf376..137b8810 100644
--- a/src/utils/calls.h
+++ b/src/utils/calls.h
@@ -26,14 +26,13 @@ CMP_DEF(le, AS);
 #define CMP_AA_IMM(FN, ELT, WHERE, WP, XP, LEN) CMP_AA_CALL(CMP_AA_FN(FN, ELT), WHERE, WP, XP, LEN)
 #define CMP_AS_IMM(FN, ELT, WHERE, WP, X,  LEN) CMP_AS_CALL(CMP_AS_FN(FN, ELT), WHERE, WP, X, LEN)
 
-// Check if the l elements starting at a and b match
 typedef bool (*EqFn)(void* a, void* b, u64 l, u64 data);
 extern INIT_GLOBAL EqFn eqFns[];
 extern u8 const eqFnData[];
 #define EQFN_INDEX(W_ELT, X_ELT) ((W_ELT)*8 + (X_ELT))
 typedef struct { EqFn fn; u8 data; } EqFnObj;
 #define EQFN_GET(W_ELT, X_ELT) ({ u8 eqfn_i_ = EQFN_INDEX(W_ELT, X_ELT); (EqFnObj){.fn=eqFns[eqfn_i_], .data=eqFnData[eqfn_i_]}; })
-#define EQFN_CALL(FN, W, X, L) (FN).fn(W, X, L, (FN).data)
+#define EQFN_CALL(FN, W, X, L) (FN).fn(W, X, L, (FN).data) // check if L elements starting at a and b match; assumes L≥1
 
 typedef bool (*RangeFn)(void* xp, i64* res, u64 len); // writes min,max in res, assumes len≥1; returns 0 and leaves res undefined if either any (floor(x)≠x or abs>2⋆53), or (x≠(i64)x)
 extern INIT_GLOBAL RangeFn getRange_fns[el_f64+1]; // limited to ≤el_f64