Question

VHDL数据类型BIT、INTEGER和BOOLEAN分别定义在哪个库中？哪些库和程序包总是可见的？

Answer 1

你是用Altera Maxplus II或Quartus II的话,应该在standard.vhd库中 对Maxplus,目录是在altera\maxplus2\vhdl93\std\standard.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;