[_CDCSL_93-16_]<1>Cedar>release>IntCode>IntCodeTarget.mesa

IntCodeTarget.mesa

Russ Atkinson (RRA) September 18, 1987 5:59:39 pm PDT

JKF July 27, 1988 8:12:07 am PDT

Willie-s, September 23, 1991 5:57 pm PDT

DIRECTORY

Basics32 USING [BITLSHIFT, BITRSHIFT],

Rope USING [ROPE];

IntCodeTarget: CEDAR DEFINITIONS

IMPORTS Basics32

= BEGIN OPEN Rope;

This file has definitions that allow us to be parameterized according to the target. Most of the variables are not constants to allow us to share more code without recompilation.

Machine description

name: READONLY ROPE;

Gives a human-readable name for the target machine. Useful for messages.

Addressing units

bitsPerAU: READONLY NAT;

logBitsPerAU: READONLY NAT;

bytesPerAU: READONLY NAT;

logBytesPerAU: READONLY NAT;

Bit order

bitOrder: READONLY BitOrder;

BitOrder: TYPE = {msBit, lsBit};

Arguments & returns

maxBitsArgumentRecord: READONLY NAT;

gives the # of bits for the largest "fast" argument record

minBitsPerArgument: READONLY NAT;

logMinBitsPerArgument: READONLY NAT;

Gives the minimum # of bits for an argument

(to get the bits for an argument, round up & shift by logMinBitsPerArgument)

maxBitsReturnRecord: READONLY NAT;

gives the # of bits for the largest "fast" return record

minBitsPerReturn: READONLY NAT;

logMinBitsPerReturn: READONLY NAT;

Gives the minimum # of bits for an return value

Global frame

bitsPerGlobal: READONLY NAT;

logBitsPerGlobal: READONLY NAT;

Gives the minimum # of bits for an global variable

firstGlobalOffset: READONLY NAT;

First offset usable for global variables (in bits)

directGlobals: READONLY BOOL;

TRUE => target supports direct use of global variables

FALSE => target requires global frame pointer

Local frame & stack

lastRegister: READONLY NAT;

Gives # of registers to be used for local variables

lastStack: READONLY NAT;

Gives last stack location to be used for passing arguments

bitsPerLocal: READONLY NAT;

logBitsPerLocal: READONLY NAT;

Gives the minimum # of bits for an local variable

bitsPerLink: READONLY NAT;

logBitsPerLink: READONLY NAT;

Gives the minimum # of bits for a link

(uniform for static link, global link, & frame extension if any).

Utility routines

ToUnits: PROC [bits: INT, minBits: NAT, logMinBits: NAT] RETURNS [INT] = INLINE {

SELECT bits FROM

<= 0 => RETURN [0];

<= minBits => RETURN [1];

ENDCASE => RETURN [Basics32.BITRSHIFT[bits+minBits-1, logMinBits]];

};

ToBits: PROC [units: INT, logBitsPerUnit: NAT] RETURNS [INT] = INLINE {

SELECT units FROM

<= 0 => RETURN [0];

ENDCASE => RETURN [Basics32.BITLSHIFT[units, logBitsPerUnit]];

};

END.