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implement binary format of date and time types
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| %%% Copyright (C) 2008 - Will Glozer. All rights reserved. | ||
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| -module(pgsql_datetime). | ||
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| -export([decode/2, encode/2]). | ||
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| -define(int16, 1/big-signed-unit:16). | ||
| -define(int32, 1/big-signed-unit:32). | ||
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| -define(postgres_epoc_jdate, 2451545). | ||
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| -define(mins_per_hour, 60). | ||
| -define(secs_per_day, 86400.0). | ||
| -define(secs_per_hour, 3600.0). | ||
| -define(secs_per_minute, 60.0). | ||
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| decode(date, <<J:1/big-signed-unit:32>>) -> j2date(?postgres_epoc_jdate + J); | ||
| decode(time, <<N:1/big-float-unit:64>>) -> f2time(N); | ||
| decode(timetz, <<N:1/big-float-unit:64, TZ:?int32>>) -> {f2time(N), TZ}; | ||
| decode(timestamp, <<N:1/big-float-unit:64>>) -> f2timestamp(N); | ||
| decode(timestamptz, <<N:1/big-float-unit:64>>) -> f2timestamp(N); | ||
| decode(interval, <<N:1/big-float-unit:64, D:?int32, M:?int32>>) -> {f2time(N), D, M}. | ||
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| encode(date, D) -> <<4:?int32, (date2j(D) - ?postgres_epoc_jdate):1/big-signed-unit:32>>; | ||
| encode(time, T) -> <<8:?int32, (time2f(T)):1/big-float-unit:64>>; | ||
| encode(timetz, {T, TZ}) -> <<12:?int32, (time2f(T)):1/big-float-unit:64, TZ:?int32>>; | ||
| encode(timestamp, TS) -> <<8:?int32, (timestamp2f(TS)):1/big-float-unit:64>>; | ||
| encode(timestamptz, TS) -> <<8:?int32, (timestamp2f(TS)):1/big-float-unit:64>>; | ||
| encode(interval, {T, D, M}) -> <<16:?int32, (time2f(T)):1/big-float-unit:64, D:?int32, M:?int32>>. | ||
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| j2date(N) -> | ||
| J = N + 32044, | ||
| Q1 = J div 146097, | ||
| Extra = (J - Q1 * 146097) * 4 + 3, | ||
| J2 = J + 60 + Q1 * 3 + Extra div 146097, | ||
| Q2 = J2 div 1461, | ||
| J3 = J2 - Q2 * 1461, | ||
| Y = J3 * 4 div 1461, | ||
| case Y of | ||
| 0 -> J4 = ((J3 + 306) rem 366) + 123; | ||
| _ -> J4 = ((J3 + 305) rem 365) + 123 | ||
| end, | ||
| Year = (Y + Q2 * 4) - 4800, | ||
| Q3 = J4 * 2141 div 65536, | ||
| Day = J4 - 7834 * Q3 div 256, | ||
| Month = (Q3 + 10) rem 12 + 1, | ||
| {Year, Month, Day}. | ||
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| date2j({Y, M, D}) -> | ||
| case M > 2 of | ||
| true -> | ||
| M2 = M + 1, | ||
| Y2 = Y + 4800; | ||
| false -> | ||
| M2 = M + 13, | ||
| Y2 = Y + 4799 | ||
| end, | ||
| C = Y2 div 100, | ||
| J1 = Y2 * 365 - 32167, | ||
| J2 = J1 + (Y2 div 4 - C + C div 4), | ||
| J2 + 7834 * M2 div 256 + D. | ||
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| f2time(N) -> | ||
| {R1, Hour} = tmodulo(N, ?secs_per_hour), | ||
| {R2, Min} = tmodulo(R1, ?secs_per_minute), | ||
| {R3, Sec} = tmodulo(R2, 1.0), | ||
| case timeround(R3) of | ||
| US when US >= 1.0 -> f2time(ceiling(N)); | ||
| US -> {Hour, Min, Sec + US} | ||
| end. | ||
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| time2f({H, M, S}) -> | ||
| ((H * ?mins_per_hour + M) * ?secs_per_minute) + S. | ||
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| f2timestamp(N) -> | ||
| case tmodulo(N, ?secs_per_day) of | ||
| {T, D} when T < 0 -> f2timestamp2(D - 1 + ?postgres_epoc_jdate, T + ?secs_per_day); | ||
| {T, D} -> f2timestamp2(D + ?postgres_epoc_jdate, T) | ||
| end. | ||
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| f2timestamp2(D, T) -> | ||
| {_H, _M, S} = Time = f2time(T), | ||
| Date = j2date(D), | ||
| case tsround(S - trunc(S)) of | ||
| N when N >= 1.0 -> | ||
| case ceiling(T) of | ||
| T2 when T2 > ?secs_per_day -> f2timestamp2(D + 1, 0.0); | ||
| T2 -> f2timestamp2(T2, D) | ||
| end; | ||
| _ -> ok | ||
| end, | ||
| {Date, Time}. | ||
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| timestamp2f({Date, Time}) -> | ||
| D = date2j(Date) - ?postgres_epoc_jdate, | ||
| D * ?secs_per_day + time2f(Time). | ||
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| tmodulo(T, U) -> | ||
| case T < 0 of | ||
| true -> Q = ceiling(T / U); | ||
| false -> Q = floor(T / U) | ||
| end, | ||
| case Q of | ||
| 0 -> {T, Q}; | ||
| _ -> {T - rint(Q * U), Q} | ||
| end. | ||
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| rint(N) -> round(N) * 1.0. | ||
| timeround(J) -> rint(J * 10000000000.0) / 10000000000.0. | ||
| tsround(J) -> rint(J * 1000000.0) / 1000000.0. | ||
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| floor(X) -> | ||
| T = erlang:trunc(X), | ||
| case (X - T) of | ||
| N when N < 0 -> T - 1; | ||
| N when N > 0 -> T; | ||
| _ -> T | ||
| end. | ||
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| ceiling(X) -> | ||
| T = erlang:trunc(X), | ||
| case (X - T) of | ||
| N when N < 0 -> T; | ||
| N when N > 0 -> T + 1; | ||
| _ -> T | ||
| end. |
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