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109 lines
4.7 KiB
Plaintext
109 lines
4.7 KiB
Plaintext
(NOTE: view this file with a monospaced font)
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eLua generic modules
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================================================================================
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Before you read this file, please make sure that you read and understood the
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theory from "platform_modules.txt" (at least the first part which describes
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the platform modules implementation). The generic modules use the exact same
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mechanism. In fact, the only difference between them is that the generic modules
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are exactly what their name implies: generic. They don't depend on the platform
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interface, so they don't need specific support for each platform, but they still
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behave identically on all platforms. They are selected by the same mechanism
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used by the platform modules (platform_libs.h). Following is a list of these
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modules and their exported functions.
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The "term" module
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================================================================================
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The "term" component (see terminal_support.txt) exports its functions to Lua via
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the "term" module. The methods of the "term" module are presented below.
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term.clrscr(): clear the screen
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term.clreol(): clear from the current cursor position to the end of the line
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term.gotoxy( x, y ): position the cursor at the given coordinates
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term.up( delta ): move the cursor up "delta" lines
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term.down( delta ): move the cursor down "delta" lines
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term.left( delta ): move the cursor left "delta" lines
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term.right( delta ): move the cursor right "delta" lines
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Lines = term.lines(): returns the number of lines
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Cols = term.cols(): returns the number of columns
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term.put( c1, c2, ... ): writes the specified character(s) to the terminal
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term.putstr( s1, s2, ... ): writes the specified string(s) to the terminal
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Cx = term.cursorx(): return the cursor X position
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Cy = term.cursory(): return the cursor Y position
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c = term.getch( term.WAIT | term.NOWAIT ): returns a char read from the
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terminal. If term.WAIT is specified the function will wait for a character to
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be ready, with term.NOWAIT it returns -1 if no char is available or the char
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code if a char is available. The return of getch can be checked against the
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char codes defined in inc/term.h, by appending "term." to the constant name
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(for example: term.KC_UP, term.KC_LEFT, term.KC_ESC ... )
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The "pack" module
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================================================================================
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Pack allows packing/unpacking of binary data. For example, it allows one to save
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a specific data type (for example a 16-bit integer) from Lua to a file and then
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read it back to a Lua variable without having to worry about the different
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physical representations of a Lua number and a 16-bit integer. It's originally
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written by Luiz Henrique de Figueiredo, one of the "fathers" of Lua.
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It exports just two methods ("pack" and "unpack"), but it uses some format
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specifiers for the pack/unpack operations that take a while to get used to. For
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more information download the original distribution and check its documentation
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and examples (http://www.tecgraf.pub-rio.br/~lhf/ftp/lua/~lpack).
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The "bit" module
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================================================================================
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As Lua doesn't have built-in operators for bit operations (and, or, xor, not)
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they are provided by this module. It's based on "bitlib" by Reuben Thomas and
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was slightly adapted and augmented for eLua.
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Res = bit.bnot( value ): unary negation
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Res = bit.band( v1, v2, ... ): binary "and"
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Res = bit.bor( v1, v2, ... ): binary "or"
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Res = bit.bxor( v1, v2, ... ): binary "exclusive or"
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Res = bit.lshift( value, pos ): shift "value" left "pos" positions.
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Res = bit.rshift( value, pos ): shift "value" right "pos" positions. The sign is
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not propagated.
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Res = bit.arshift( value, pos ): shift "value" right "pos" positions. The sign
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is propagated ("arithmetic shift").
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Res = bit.bit( bitno ): a shortcut for bit.lshift( 1, bitno )
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Res1, Res2, ... = bit.set( bitno, v1, v2, ... ): set the bit at position "bitno"
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in v1, v2, ... to 1.
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Res1, Res2, ... = bit.clear( bitno, v1, v2, ... ): set the bit at position
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"bitno"in v1, v2, ... to 0.
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Res = bit.isset( value, bitno ): returns true if bit at position "bitno" in
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"value" is 1, false otherwise.
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Res = bit.isclear( value, bitno ): returns true if bit at position "bitno" in
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"value" is 0, false otherwise.
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The "math" module
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================================================================================
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This is actually part of the official Lua distribution, not a separate module.
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Its purpose is to provide mathematic functiosn (sin, cos, tan...) to Lua. Since
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these kind of functions are rarely needed in an embedded environment, the "math"
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module can be enabled and disabled just like the other generic and platform
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modules in eLua.
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