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

IntCodeTargetImpl.mesa

Russ Atkinson (RRA) December 4, 1987 3:35:18 pm PST

JKF July 27, 1988 8:17:08 am PDT

DIRECTORY

IntCodeTarget USING [BitOrder],

Rope USING [ROPE],

Target: TYPE MachineParms USING [BitOrder, bitOrder, bitsPerAU, bitsPerByte, bitsPerWord];

IntCodeTargetImpl: CEDAR PROGRAM

EXPORTS IntCodeTarget

= BEGIN

ROPE: TYPE = Rope.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: PUBLIC ROPE ¬ "Sun-3/4";

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

Addressing units

bitsPerAU: PUBLIC NAT ¬ Target.bitsPerAU;

logBitsPerAU: PUBLIC NAT ¬ ExactLog2[bitsPerAU];

bytesPerAU: PUBLIC NAT ¬ Target.bitsPerAU/Target.bitsPerByte;

logBytesPerAU: PUBLIC NAT ¬ ExactLog2[bytesPerAU];

Bit order

bitOrder: PUBLIC IntCodeTarget.BitOrder ¬ SELECT Target.bitOrder FROM

$msBit => $msBit,

$lsBit => $lsBit,

ENDCASE => ERROR;

Arguments & returns

maxBitsArgumentRecord: PUBLIC NAT ¬ 16*Target.bitsPerWord;

gives the max # of direct argument words

minBitsPerArgument: PUBLIC NAT ¬ Target.bitsPerWord;

logMinBitsPerArgument: PUBLIC NAT ¬ ExactLog2[minBitsPerArgument];

Gives the minimum # of bits for an argument

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

maxBitsReturnRecord: PUBLIC NAT ¬ 1*Target.bitsPerWord;

gives the max # of direct return words

minBitsPerReturn: PUBLIC NAT ¬ Target.bitsPerWord;

logMinBitsPerReturn: PUBLIC NAT ¬ ExactLog2[minBitsPerReturn];

Gives the minimum # of bits for an return value

Global frame

bitsPerGlobal: PUBLIC NAT ¬ Target.bitsPerWord;

logBitsPerGlobal: PUBLIC NAT ¬ ExactLog2[bitsPerGlobal];

Gives the minimum # of bits for an global variable

(can be different than locals)

firstGlobalOffset: PUBLIC NAT ¬ 4*Target.bitsPerWord;

First offset usable for global variables (in bits)

(what should this be?)

directGlobals: PUBLIC BOOL ¬ FALSE;

TRUE => target supports direct use of global variables

FALSE => target requires global frame pointer

Local frame & stack

lastRegister: PUBLIC NAT ¬ 0;

Gives # of registers to be used for local variables

lastStack: PUBLIC NAT ¬ 0;

Gives last stack location to be used for passing arguments

bitsPerLocal: PUBLIC NAT ¬ Target.bitsPerWord;

logBitsPerLocal: PUBLIC NAT ¬ ExactLog2[bitsPerLocal];

Gives the minimum # of bits for a local variable

bitsPerLink: PUBLIC NAT ¬ Target.bitsPerWord;

logBitsPerLink: PUBLIC NAT ¬ ExactLog2[bitsPerLink];

Gives the minimum # of bits for a link

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

ExactLog2: PROC [n: NAT] RETURNS [log2: NAT ¬ 2] = {

RETURN [SELECT n FROM

1 => 0, 2 => 1, 4 => 2, 8 => 3, 16 => 4, 32 => 5, 64 => 6, 128 => 7,

256 => 8, 512 => 9, 1024 => 10, 2048 => 11, 4096 => 12, 8192 => 13, 16384 => 14

ENDCASE => ERROR];

};

END.