2 Package checked implements basic arithmetic operations
3 with underflow and overflow checks.
12 var ErrOverflow = errors.New("arithmetic overflow")
14 // AddInt64 returns a + b
15 // with an integer overflow check.
16 func AddInt64(a, b int64) (sum int64, ok bool) {
17 if (b > 0 && a > math.MaxInt64-b) ||
18 (b < 0 && a < math.MinInt64-b) {
24 // SubInt64 returns a - b
25 // with an integer overflow check.
26 func SubInt64(a, b int64) (diff int64, ok bool) {
27 if (b > 0 && a < math.MinInt64+b) ||
28 (b < 0 && a > math.MaxInt64+b) {
34 // MulInt64 returns a * b
35 // with an integer overflow check.
36 func MulInt64(a, b int64) (product int64, ok bool) {
37 if (a > 0 && b > 0 && a > math.MaxInt64/b) ||
38 (a > 0 && b <= 0 && b < math.MinInt64/a) ||
39 (a <= 0 && b > 0 && a < math.MinInt64/b) ||
40 (a < 0 && b <= 0 && b < math.MaxInt64/a) {
46 // DivInt64 returns a / b
47 // with an integer overflow check.
48 func DivInt64(a, b int64) (quotient int64, ok bool) {
49 if b == 0 || (a == math.MinInt64 && b == -1) {
55 // ModInt64 returns a % b
56 // with an integer overflow check.
57 func ModInt64(a, b int64) (remainder int64, ok bool) {
58 if b == 0 || (a == math.MinInt64 && b == -1) {
64 // NegateInt64 returns -a
65 // with an integer overflow check.
66 func NegateInt64(a int64) (negated int64, ok bool) {
67 if a == math.MinInt64 {
73 // LshiftInt64 returns a << b
74 // with an integer overflow check.
75 func LshiftInt64(a, b int64) (result int64, ok bool) {
79 if (a >= 0 && a > math.MaxInt64>>uint(b)) || (a < 0 && a < math.MinInt64>>uint(b)) {
82 return a << uint(b), true
85 // AddInt32 returns a + b
86 // with an integer overflow check.
87 func AddInt32(a, b int32) (sum int32, ok bool) {
88 if (b > 0 && a > math.MaxInt32-b) ||
89 (b < 0 && a < math.MinInt32-b) {
95 // SubInt32 returns a - b
96 // with an integer overflow check.
97 func SubInt32(a, b int32) (diff int32, ok bool) {
98 if (b > 0 && a < math.MinInt32+b) ||
99 (b < 0 && a > math.MaxInt32+b) {
105 // MulInt32 returns a * b
106 // with an integer overflow check.
107 func MulInt32(a, b int32) (product int32, ok bool) {
108 if (a > 0 && b > 0 && a > math.MaxInt32/b) ||
109 (a > 0 && b <= 0 && b < math.MinInt32/a) ||
110 (a <= 0 && b > 0 && a < math.MinInt32/b) ||
111 (a < 0 && b <= 0 && b < math.MaxInt32/a) {
117 // DivInt32 returns a / b
118 // with an integer overflow check.
119 func DivInt32(a, b int32) (quotient int32, ok bool) {
120 if b == 0 || (a == math.MinInt32 && b == -1) {
126 // ModInt32 returns a % b
127 // with an integer overflow check.
128 func ModInt32(a, b int32) (remainder int32, ok bool) {
129 if b == 0 || (a == math.MinInt32 && b == -1) {
135 // NegateInt32 returns -a
136 // with an integer overflow check.
137 func NegateInt32(a int32) (negated int32, ok bool) {
138 if a == math.MinInt32 {
144 // LshiftInt32 returns a << b
145 // with an integer overflow check.
146 func LshiftInt32(a, b int32) (result int32, ok bool) {
147 if b < 0 || b >= 32 {
150 if (a >= 0 && a > math.MaxInt32>>uint(b)) || (a < 0 && a < math.MinInt32>>uint(b)) {
153 return a << uint(b), true
156 // AddUint64 returns a + b
157 // with an integer overflow check.
158 func AddUint64(a, b uint64) (sum uint64, ok bool) {
159 if math.MaxUint64-a < b {
165 // SubUint64 returns a - b
166 // with an integer overflow check.
167 func SubUint64(a, b uint64) (diff uint64, ok bool) {
174 // MulUint64 returns a * b
175 // with an integer overflow check.
176 func MulUint64(a, b uint64) (product uint64, ok bool) {
177 if b > 0 && a > math.MaxUint64/b {
183 // DivUint64 returns a / b
184 // with an integer overflow check.
185 func DivUint64(a, b uint64) (quotient uint64, ok bool) {
192 // ModUint64 returns a % b
193 // with an integer overflow check.
194 func ModUint64(a, b uint64) (remainder uint64, ok bool) {
201 // LshiftUint64 returns a << b
202 // with an integer overflow check.
203 func LshiftUint64(a, b uint64) (result uint64, ok bool) {
207 if a > math.MaxUint64>>uint(b) {
210 return a << uint(b), true
213 // AddUint32 returns a + b
214 // with an integer overflow check.
215 func AddUint32(a, b uint32) (sum uint32, ok bool) {
216 if math.MaxUint32-a < b {
222 // SubUint32 returns a - b
223 // with an integer overflow check.
224 func SubUint32(a, b uint32) (diff uint32, ok bool) {
231 // MulUint32 returns a * b
232 // with an integer overflow check.
233 func MulUint32(a, b uint32) (product uint32, ok bool) {
234 if b > 0 && a > math.MaxUint32/b {
240 // DivUint32 returns a / b
241 // with an integer overflow check.
242 func DivUint32(a, b uint32) (quotient uint32, ok bool) {
249 // ModUint32 returns a % b
250 // with an integer overflow check.
251 func ModUint32(a, b uint32) (remainder uint32, ok bool) {
258 // LshiftUint32 returns a << b
259 // with an integer overflow check.
260 func LshiftUint32(a, b uint32) (result uint32, ok bool) {
264 if a > math.MaxUint32>>uint(b) {
267 return a << uint(b), true