lib/kru: fix zero increment

diff --git a/lib/kru.inc.c b/lib/kru.inc.c
index 53a9f97b7103846a5f6178da4e0e2e39306438b2..078c8f067e9a0ecab26ec2cae0781b0a3cfe50e7 100644 (file)
--- a/lib/kru.inc.c
+++ b/lib/kru.inc.c
@@ -229,7 +229,8 @@ struct query_ctx {
        struct load_cl *l[TABLE_COUNT];
        uint32_t time_now;
        kru_price_t price;
-       uint16_t price16, limit16;
+       uint16_t price16;
+       uint32_t limit16;  // 2^16 has to be representable
        uint16_t id;
        uint16_t final_load_value;  // set by kru_limited_update if not blocked
        uint16_t *load;
@@ -360,7 +361,7 @@ static inline bool kru_limited_fetch(struct kru *kru, struct query_ctx *ctx)
                const kru_price_t fract = price & ((((kru_price_t)1) << fract_bits) - 1);
 
                ctx->price16 = price >> fract_bits;
-               ctx->limit16 = -ctx->price16;
+               ctx->limit16 = (1<<16) - ctx->price16;
 
                if ((fract_bits > 0) && (fract > 0)) {
                        ctx->price16 += (rand_bits(fract_bits) < fract);
@@ -474,7 +475,7 @@ static inline bool kru_limited_update(struct kru *kru, struct query_ctx *ctx, bo
 
        static_assert(ATOMIC_CHAR16_T_LOCK_FREE == 2, "insufficient atomics");
        const uint16_t price = ctx->price16;
-       const uint16_t limit = ctx->limit16;
+       const uint32_t limit = ctx->limit16;  // 2^16 has to be representable
        uint16_t load_orig = atomic_load_explicit(load_at, memory_order_relaxed);
        uint16_t load_new;
        do {