gno.land/p/samcrew/launchpad/safemath/v1⧉

1// Package safemath is checked, non-negative int64 arithmetic for launchpad amounts.2package safemath34import "math/bits"56const (7	MaxInt64       int64 = 1<<63 - 18	BPSDenominator int64 = 10_0009)1011func mustNonNegative(v int64) {12	if v < 0 {13		panic("launchpad/safemath: negative value")14	}15}1617func Add(a, b int64) int64 {18	mustNonNegative(a)19	mustNonNegative(b)20	if a > MaxInt64-b {21		panic("launchpad/safemath: overflow")22	}23	return a + b24}2526func Sub(a, b int64) int64 {27	mustNonNegative(a)28	mustNonNegative(b)29	if b > a {30		panic("launchpad/safemath: underflow")31	}32	return a - b33}3435func Mul(a, b int64) int64 {36	mustNonNegative(a)37	mustNonNegative(b)38	if a != 0 && b > MaxInt64/a {39		panic("launchpad/safemath: overflow")40	}41	return a * b42}4344// MulDiv returns floor(a*b/d) using a 128-bit intermediate.45func MulDiv(a, b, d int64) int64 {46	q, _ := mulDivRem(a, b, d)47	return q48}4950// MulDivUp returns ceil(a*b/d) using a 128-bit intermediate.51func MulDivUp(a, b, d int64) int64 {52	q, rem := mulDivRem(a, b, d)53	if rem {54		if q == MaxInt64 {55			panic("launchpad/safemath: overflow")56		}57		q++58	}59	return q60}6162func mulDivRem(a, b, d int64) (int64, bool) {63	mustNonNegative(a)64	mustNonNegative(b)65	if d <= 0 {66		panic("launchpad/safemath: division by zero")67	}68	hi, lo := bits.Mul64(uint64(a), uint64(b))69	if hi >= uint64(d) {70		panic("launchpad/safemath: overflow")71	}72	q, r := bits.Div64(hi, lo, uint64(d))73	if q > uint64(MaxInt64) {74		panic("launchpad/safemath: overflow")75	}76	return int64(q), r != 077}7879// BPS returns floor(amount*bps/10000) for 0 <= bps <= 10000.80func BPS(amount, bps int64) int64 {81	if bps < 0 || bps > BPSDenominator {82		panic("launchpad/safemath: basis points out of range")83	}84	return MulDiv(amount, bps, BPSDenominator)85}8687func Min(a, b int64) int64 {88	if a < b {89		return a90	}91	return b92}93