void HuffmanDecoder::Initialize(const unsigned int *codeBits, unsigned int nCodes)
{
// the Huffman codes are represented in 3 ways in this code:
//
// 1. most significant code bit (i.e. top of code tree) in the least significant bit position
// 2. most significant code bit (i.e. top of code tree) in the most significant bit position
// 3. most significant code bit (i.e. top of code tree) in n-th least significant bit position,
// where n is the maximum code length for this code tree
//
// (1) is the way the codes come in from the deflate stream
// (2) is used to sort codes so they can be binary searched
// (3) is used in this function to compute codes from code lengths
//
// a code in representation (2) is called "normalized" here
// The BitReverse() function is used to convert between (1) and (2)
// The NormalizeCode() function is used to convert from (3) to (2)
if (nCodes == 0)
throw Err("null code");
m_maxCodeBits = *std::max_element(codeBits, codeBits+nCodes);
if (m_maxCodeBits > MAX_CODE_BITS)
throw Err("code length exceeds maximum");
if (m_maxCodeBits == 0)
throw Err("null code");
// count number of codes of each length
SecBlockWithHint<unsigned int, 15+1> blCount(m_maxCodeBits+1);
std::fill(blCount.begin(), blCount.end(), 0);
unsigned int i;
for (i=0; i<nCodes; i++)
blCount[codeBits[i]]++;
// compute the starting code of each length
code_t code = 0;
SecBlockWithHint<code_t, 15+1> nextCode(m_maxCodeBits+1);
nextCode[1] = 0;
for (i=2; i<=m_maxCodeBits; i++)
{
// compute this while checking for overflow: code = (code + blCount[i-1]) << 1
if (code > code + blCount[i-1])
throw Err("codes oversubscribed");
code += blCount[i-1];
if (code > (code << 1))
throw Err("codes oversubscribed");
code <<= 1;
nextCode[i] = code;
}
if (code > (1 << m_maxCodeBits) - blCount[m_maxCodeBits])
throw Err("codes oversubscribed");
else if (m_maxCodeBits != 1 && code < (1 << m_maxCodeBits) - blCount[m_maxCodeBits])
throw Err("codes incomplete");
// compute a vector of <code, length, value> triples sorted by code
m_codeToValue.resize(nCodes - blCount[0]);
unsigned int j=0;
for (i=0; i<nCodes; i++)
{
unsigned int len = codeBits[i];
if (len != 0)
{
code = NormalizeCode(nextCode[len]++, len);
m_codeToValue[j].code = code;
m_codeToValue[j].len = len;
m_codeToValue[j].value = i;
j++;
}
}
std::sort(m_codeToValue.begin(), m_codeToValue.end());
// initialize the decoding cache
m_cacheBits = STDMIN(9U, m_maxCodeBits);
m_cacheMask = (1 << m_cacheBits) - 1;
m_normalizedCacheMask = NormalizeCode(m_cacheMask, m_cacheBits);
CRYPTOPP_ASSERT(m_normalizedCacheMask == BitReverse(m_cacheMask));
if (m_cache.size() != size_t(1) << m_cacheBits)
m_cache.resize(1 << m_cacheBits);
for (i=0; i<m_cache.size(); i++)
m_cache[i].type = 0;
}
void statement() /* 문 */
{
CodeSet save;
int top_line, end_line, varAdrs;
double wkVal, endDt, stepDt;
if (Pc>maxLine || exit_Flg) return; /* 프로그램 종료 */
code = save = firstCode(Pc);
top_line = Pc; end_line = code.jmpAdrs; /* 제어 범위의 시작과 끝 */
if (code.kind == If ) end_line = endline_of_If(Pc); /* if문일 때의 끝 */
switch (code.kind) {
case If:
// if
if (get_expression(If, 0)) { /* 참(TRUE)이면 */
++Pc; block(); Pc = end_line + 1; /* 실행하고 */
return; /* 종료 */
}
Pc = save.jmpAdrs; /* 다음으로 */
// elif
while (lookCode(Pc) == Elif) {
save = firstCode(Pc); code = nextCode();
if (get_expression()) { /* 참(TRUE)이면 */
++Pc; block(); Pc = end_line + 1; /* 실행하고 */
return; /* 종료 */
}
Pc = save.jmpAdrs; /* 다음으로 */
}
// else
if (lookCode(Pc) == Else) { /* else를 */
++Pc; block(); Pc = end_line + 1; /* 실행하고 */
return; /* 종료 */
}
// end
++Pc;
break;
case While:
for (;;) { /* */
if (!get_expression(While, 0)) break; /* false 종료 */
++Pc; block(); /* [실행] */
if (break_Flg || return_Flg || exit_Flg) { /* */
break_Flg = false; break; /* 중단 */
} /* */
Pc = top_line; code = firstCode(Pc); /* 맨 앞으로 */
} /* */
Pc = end_line + 1; /* */
break;
case For: /* for 제어변수, 초깃값, 최종값, 증분식 */
save = nextCode();
varAdrs = get_memAdrs(save); /* 제이변수 주소 구하기 */
expression('=', 0); /* 초깃값 */
set_dtTyp(save, DBL_T); /* 형 확정 */
Dmem.set(varAdrs, stk.pop()); /* 초깃값을 설정 */
endDt = get_expression(To, 0); /* 최종값을 보존 */
/* 증분값을 보존 */
if (code.kind == Step) stepDt = get_expression(Step, 0); else stepDt = 1.0;
for (;; Pc=top_line) { /* */
if (stepDt >= 0) { /* 증가 루프 */
if (Dmem.get(varAdrs) > endDt) break; /* 거짓이면 종료 */
} else { /* 감소 루프 */
if (Dmem.get(varAdrs) < endDt) break; /* 거짓이면 종료 */
} /* */
++Pc; block(); /* [ 실행 ] */
if (break_Flg || return_Flg || exit_Flg) { /* */
break_Flg = false; break; /* 중단 */
} /* */
Dmem.add(varAdrs, stepDt); /* 값 갱신 */
} /* */
Pc = end_line + 1; /* */
break;
case Fcall: /* 대입이 없는 함수 호출 */
fncCall(code.symNbr);
(void)stk.pop(); /* 반환 값 불필요 */
++Pc;
break;
case Func: /* 함수 정의는 건너뀜 */
Pc = end_line + 1;
break;
case Print: case Println:
sysFncExec(code.kind);
++Pc;
break;
case Gvar: case Lvar: /* 대입문 */
varAdrs = get_memAdrs(code);
expression('=', 0);
set_dtTyp(save, DBL_T); /* 대입할 때 형 확정*/
Dmem.set(varAdrs, stk.pop());
++Pc;
break;
case Return:
wkVal = returnValue;
code = nextCode();
if (code.kind!='?' && code.kind!=EofLine) /* '식'이 있으면 반환 값을 계산 */
wkVal = get_expression();
post_if_set(return_Flg); /* ?가 있으면 처리 */
if (return_Flg) returnValue = wkVal;
if (!return_Flg) ++Pc;
break;
case Break:
code = nextCode(); post_if_set(break_Flg); /* ? 가 있으면 처리 */
if (!break_Flg) ++Pc;
break;
case Exit:
code = nextCode(); exit_Flg = true;
break;
case Option: case Var: case EofLine: /* 실행 시는 무시 */
++Pc;
break;
default:
err_exit("잘못된 기술입니다: ", kind_to_s(code.kind));
}
}
void statement() /* 文のコンパイル */
{
int tIndex;
KindT k;
int backP, backP2,backP3; /* バックパッチ用 */
while(1) {
switch (token.kind) {
case Id: /* 代入文のコンパイル */
tIndex = searchT(token.u.id, varId); /* 左辺の変数のインデックス */
setIdKind(k=kindT(tIndex)); /* 印字のための情報のセット */
if (k != varId && k != parId) /* 変数名かパラメタ名のはず */
errorType("var/par");
token = checkGet(nextToken(), Assign); /* ":="のはず */
expression(); /* 式のコンパイル */
genCodeT(sto, tIndex); /* 左辺への代入命令 */
return;
case If: /* if文のコンパイル */
token = nextToken();
condition(); /* 条件式のコンパイル */
token = checkGet(token, Then); /* "then"のはず */
backP = genCodeV(jpc, 0); /* jpc命令 */
statement(); /* 文のコンパイル */
/*-------------*/
token = checkGet(token,Else);
backP2 = genCodeV(jmp,0);
backP3 = nextCode();
statement();
/*変更部分*/
backChange(backP,backP3);
backPatch(backP2);/* 上のjmp命令にバックパッチ */
return;
/*--------------------
変更部分
----------------------*/
case Do:
token = nextToken(); /**/
backP2 = nextCode(); /*while分のconditionが真だった時の飛び先*/
statement(); /*文のコンパイル*/
token = checkGet(nextToken(),While);/*"while"の筈*/
condition();
backP = genCodeV(jpc,0); /*偽の時飛び出すjpc命令*/
genCodeV(jmp,backP2);
backPatch(backP);
return;
case Repeat:
token = nextToken();
backP2 = nextCode();
statement();
token = checkGet(nextToken(),Until);/*untilの筈*/
condition();
genCodeV(jpc,backP2);
backP = genCodeV(jmp,0);
backPatch(backP);
return;
case Ret: /* return文のコンパイル */
token = nextToken();
expression(); /* 式のコンパイル */
genCodeR(); /* ret命令 */
return;
case Begin: /* begin . . end文のコンパイル */
token = nextToken();
while(1){
statement(); /* 文のコンパイル */
while(1){
if (token.kind==Semicolon){ /* 次が";"なら文が続く */
token = nextToken();
break;
}
if (token.kind==End){ /* 次がendなら終り */
token = nextToken();
return;
}
if (isStBeginKey(token)){ /* 次が文の先頭記号なら */
errorInsert(Semicolon); /* ";"を忘れたことにする */
break;
}
errorDelete(); /* それ以外ならエラーとして読み捨てる */
token = nextToken();
}
}
case While: /* while文のコンパイル */
token = nextToken();
backP2 = nextCode(); /* while文の最後のjmp命令の飛び先 */
condition(); /* 条件式のコンパイル */
token = checkGet(token, Do); /* "do"のはず */
backP = genCodeV(jpc, 0); /* 条件式が偽のとき飛び出すjpc命令 */
statement(); /* 文のコンパイル */
genCodeV(jmp, backP2); /* while文の先頭へのジャンプ命令 */
backPatch(backP); /* 偽のとき飛び出すjpc命令へのバックパッチ */
return;
case Write: /* write文のコンパイル */
token = nextToken();
expression(); /* 式のコンパイル */
genCodeO(wrt); /* その値を出力するwrt命令 */
return;
case WriteLn: /* writeln文のコンパイル */
token = nextToken();
genCodeO(wrl); /* 改行を出力するwrl命令 */
return;
case End: case Semicolon: /* 空文を読んだことにして終り */
return;
default: /* 文の先頭のキーまで読み捨てる */
errorDelete(); /* 今読んだトークンを読み捨てる */
token = nextToken();
continue;
}
}
}
