

DIRECTORY
MesaBasics USING [CHARPtr, WORDPtr],
Basics;

MesaBasicsImpl: PROGRAM 
IMPORTS Basics
EXPORTS MesaBasics
 = {

upw: CARDINAL = UNITS[WORD];
bitsPerWord: CARDINAL = BITS[WORD];
WORDPtr: TYPE ~ MesaBasics.WORDPtr;
CHARPtr: TYPE = MesaBasics.CHARPtr;

ExternalNames: PROC [] = TRUSTED MACHINE CODE  {
"^ExternalNames\n";
"MoveWords XR_MoveWords\n";
"MoveWordsDisjoint XR_MoveWordsDisjoint\n";
"EqualWords XR_EqualWords\n";
"MoveBytes XR_MoveBytes\n";
"MoveBytesDisjoint XR_MoveBytesDisjoint\n";
"ExtractField XR_ExtractField\n";
"DepositField XR_DepositField\n";
"MoveField XR_MoveField\n";
"EqualFields XR_EqualFields\n";
"FillFields XR_FillFields\n";
"FillLongFields XR_FillLongFields\n";
"FillWords XR_FillWords\n";
"FillLongWords XR_FillLongWords\n";};


MoveWords: PUBLIC PROC [dst, src: WORDPtr, len: CARDINAL] = {
Basics.MoveWords[dst: LOOPHOLE[dst], src: LOOPHOLE[src], count: len];
};
MoveWordsDisjoint: PUBLIC PROC [dst, src: WORDPtr, len: CARDINAL] =  {
IF LOOPHOLE[dst, CARD] MOD 4 + LOOPHOLE[src, CARD] MOD 4 = 0
THEN {
Basics.CopyWords[dst: LOOPHOLE[dst], src: LOOPHOLE[src], count: len];
}
ELSE {
MoveBytes[LOOPHOLE[dst], LOOPHOLE[src], len * BYTES[WORD]]
};
};

EqualWords: PUBLIC PROC [src1, src2: WORDPtr, len: CARDINAL] RETURNS[CARD] = {
c: Basics.Comparison ~ Basics.CompareBits[
aBase: LOOPHOLE[src1], aStart: 0,
bBase: LOOPHOLE[src2], bStart: 0,
count: len * BITS[WORD]
];
RETURN [ORD[c=equal]]
};

MoveBytes: PUBLIC PROC [dest, src: CHARPtr, len: CARDINAL] = {
check: [4..4] ~ BYTES[WORD];
dstStart: CARD ~ LOOPHOLE[dest, CARD] MOD BYTES[WORD];
srcStart: CARD ~ LOOPHOLE[src, CARD] MOD BYTES[WORD];
destWP: CARD ~ LOOPHOLE[dest, CARD]-dstStart;
srcWP: CARD ~ LOOPHOLE[src, CARD]-srcStart;
Basics.MoveBytes[
dstBase: LOOPHOLE[destWP], dstStart: dstStart,
srcBase: LOOPHOLE[srcWP], srcStart: srcStart,
count: len
]
};

MoveBytesDisjoint: PUBLIC PROC [dest, src: CHARPtr, len: CARDINAL] = {
check: [4..4] ~ BYTES[WORD];
dstStart: CARD ~ LOOPHOLE[dest, CARD] MOD BYTES[WORD];
srcStart: CARD ~ LOOPHOLE[src, CARD] MOD BYTES[WORD];
destWP: CARD ~ LOOPHOLE[dest, CARD]-dstStart;
srcWP: CARD ~ LOOPHOLE[src, CARD]-srcStart;
Basics.CopyBytes[
dstBase: LOOPHOLE[destWP], dstStart: dstStart,
srcBase: LOOPHOLE[srcWP], srcStart: srcStart,
count: len
];
};

ExtractField: PUBLIC PROC [base: WORDPtr, offset: INT, bits: CARD] RETURNS [WORD] = {
w: WORD м 0;
WHILE offset < 0 DO
offset м offset + BITS[WORD];
base м base - SIZE[WORD];
ENDLOOP;
Basics.CopyBits[
dstBase: LOOPHOLE[@w], dstStart: BITS[WORD]-bits,
srcBase: LOOPHOLE[base], srcStart: offset,
count: bits
];
RETURN[w];
};

DepositField: PUBLIC PROC[base: WORDPtr, offset: INT, bits: CARD, w: WORD] = {
WHILE offset < 0 DO
offset м offset + BITS[WORD];
base м base - SIZE[WORD];
ENDLOOP;
Basics.CopyBits[
dstBase: LOOPHOLE[base], dstStart: offset,
srcBase: LOOPHOLE[@w], srcStart: BITS[WORD]-bits,
count: bits
];
};

MoveField: PUBLIC PROC [dst: WORDPtr, dstOffset: INT, src: WORDPtr, srcOffset: INT, bits: CARD] = {
WHILE dstOffset < 0 DO
dstOffset м dstOffset + BITS[WORD];
dst м dst - SIZE[WORD];
ENDLOOP;
WHILE srcOffset < 0 DO
srcOffset м srcOffset + BITS[WORD];
src м src - SIZE[WORD];
ENDLOOP;
Basics.CopyBits[
dstBase: LOOPHOLE[dst], dstStart: dstOffset,
srcBase: LOOPHOLE[src], srcStart: srcOffset,
count: bits
];
};

EqualFields: PUBLIC PROC[x: WORDPtr, xOffset: INT, y: WORDPtr, yOffset: INT, bits: CARD] RETURNS [INT] = {
WHILE xOffset < 0 DO
xOffset м xOffset + BITS[WORD];
x м x - SIZE[WORD];
ENDLOOP;
WHILE yOffset < 0 DO
yOffset м yOffset + BITS[WORD];
y м y - SIZE[WORD];
ENDLOOP;
RETURN [ORD[Basics.CompareBits[LOOPHOLE[x], xOffset, LOOPHOLE[y], yOffset, bits]=equal]]
};

FillFields: PUBLIC PROC [dst: WORDPtr, dstOffset: INT, bits: CARD, times: CARD, value: CARD] = {
FillLongFields[dst, dstOffset, LOOPHOLE[@value], bitsPerWord - bits, bits, times];
};

FillLongFields: PUBLIC PROC [dst: WORDPtr, dstOffset: INT, src: WORDPtr, srcOffset: INT, bits: CARD, times: CARD] = {
WHILE dstOffset < 0 DO
dstOffset м dstOffset + BITS[WORD];
dst м dst - SIZE[WORD];
ENDLOOP;
WHILE srcOffset < 0 DO
srcOffset м srcOffset + BITS[WORD];
src м src - SIZE[WORD];
ENDLOOP;
WHILE times > 0 DO
Basics.CopyBits[
dstBase: LOOPHOLE[dst], dstStart: dstOffset,
srcBase: LOOPHOLE[src], srcStart: srcOffset,
count: bits
];
dstOffset м dstOffset + bits;
times м times - 1;
ENDLOOP;
};

FillWords: PUBLIC PROC[dst: WORDPtr, times: CARD, value: CARD] = {
IF LOOPHOLE[dst, CARD] MOD 4 # 0
THEN {
WHILE times > 0 DO 
[] м MoveWords[dst, LOOPHOLE[@value], 1];
dst м dst + upw;
times м times - 1;
ENDLOOP;
}
ELSE {
Basics.FillWords[dst: LOOPHOLE[dst], count: times, value: value];
};
};

FillLongWords: PUBLIC PROC[dst, src: WORDPtr, nWords, times: CARD] = {
IF (nWords = 1) THEN FillWords[dst, times, src[0]]
ELSE
WHILE times > 0 DO 
[] м MoveWords[dst, src, nWords];
dst м dst + nWords*upw;
times м times - 1;
ENDLOOP;
};


ExternalNames[];

}...

   ╓  MesaBasicsImpl.mesa
Copyright ╙ 1989, 1990, 1991, 1992 by Xerox Corporation.  All rights reserved.
JKF August 13, 1990 12:20:32 pm PDT -- added EqualFields from Akira
Christian Jacobi, October 12, 1992 2:01 pm PDT
Willie-s, August 5, 1991 5:31 pm PDT
Michael Plass, October 1, 1991 12:27 pm PDT
Mesa translation of basics.c
MoveWords Moves len words (where a word is an 'int') from src to dst. The caller does not assure disjointness.

MoveWordsDisjoint Moves len words (where a word is an 'int') from src to dst. For efficiency, the caller assures disjointedness. 
both pointers are word-aligned! 
Misaligned arguments (should this ever happen)?
Tests the two multi-word variables for equality.
MoveBytes Moves len bytes from src to dest, and returns src. No assumptions are made about disjointedness.  The pointers are not necessarily aligned on word boundaries
MoveBytesDisjoint Moves len bytes from src to dest, and returns src. For efficiency, the caller assures disjointedness. 
ExtractField Extracts the field from any base pointer (pointer to word) at any bit offset. The word given has the bits right-justified. The other bits are set to zero.
DepositField Deposits the field to any base pointer at any bit offset. The word given has the bits right-justified. The other bits are ignored.
MoveField Moves 'bits' bits from src to dest.
EqualFields Tests bitfields for equality.
FillLongFields Fills contiguous fields that each are bits wide in the dst address (plus dstOffset bits) for times number of fields.  The fill value is taken from the src address (plus srcOffset bits).
FillWords Fills times words at the destination with value.
FillLongWords Fills times nWords fields at the destination (dst) with the nWords field at the src.
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