- Chen
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你是用Altera Maxplus II或Quartus II的话,应该在standard.vhd库中 对Maxplus,目录是在alteramaxplus2vhdl93stdstandard.vhd, 如果是Quartus II的话,你自己搜索一下吧. package STANDARD is -- Predefined enumeration types type BOOLEAN is (FALSE, TRUE); type BIT is ("0", "1"); type CHARACTER IS ( NUL, SOH, STX, ETX, EOT, ENQ, ACK, BEL, BS, HT, LF, VT, FF, CR, SO, SI, DLE, DC1, DC2, DC3, DC4, NAK, SYN, ETB, CAN, EM, SUB, ESC, FSP, GSP, RSP, USP, " ", "!", """, "#", "$", "%", "&", """, "(", ")", "*", "+", ",", "-", ".", "/", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", ":", ";", "<", "=", ">", "?", "@", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"," "[", "", "]", "^", "_", "`", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"," "{", "|", "}", "~", DEL, C128, C129, C130, C131, C132, C133, C134, C135, C136, C137, C138, C139, C140, C141, C142, C143, C144, C145, C146, C147, C148, C149, C150, C151, C152, C153, C154, C155, C156, C157, C158, C159, "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?", "?"); type SEVERITY_LEVEL is (NOTE, WARNING, ERROR, FAILURE); -- Predefined numeric types type INTEGER is range -2147483648 to 2147483647; type REAL is range -1.7e38 to 1.7e38; -- Predefined type TIME type TIME is range -9223372036854775808 to 9223372036854775807 units fs; -- femtosecond ps = 1000 fs; -- picosecond ns = 1000 ps; -- nanosecond us = 1000 ns; -- microsecond ms = 1000 us; -- millisecond sec = 1000 ms; -- second min = 60 sec; -- minute hr = 60 min; -- hour end units; subtype DELAY_LENGTH is TIME range 0 fs to TIME"HIGH; -- A function that returns the current simulation time, Tc (see Section 12.6.4): impure function NOW return DELAY_LENGTH; -- Predefined numeric subtypes: subtype NATURAL is INTEGER range 0 to INTEGER"HIGH; subtype POSITIVE is INTEGER range 1 to INTEGER"HIGH; -- Predefined array types: type STRING is array (POSITIVE range <>) of CHARACTER; type BIT_VECTOR is array (NATURAL range <>) of BIT; -- The predefined types for opening files: type FILE_OPEN_KIND is ( READ_MODE, -- Resulting access mode is read-only. WRITE_MODE, -- Resulting access mode is write-only. APPEND_MODE); -- Resulting access mode is write-only; information -- is appended to the end of the existing file. type FILE_OPEN_STATUS is ( OPEN_OK, -- File open was successful. STATUS_ERROR, -- File object was already open. NAME_ERROR, -- External file not found or inaccessible. MODE_ERROR); -- Could not open file with requested access mode. -- The "FOREIGN attribute: attribute FOREIGN: STRING; end STANDARD;