add boolean tests and IF/ELSE/END
git-svn-id: http://skia.googlecode.com/svn/trunk@344 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/forth/Forth.cpp b/forth/Forth.cpp
index 722ed08..01ed204 100644
--- a/forth/Forth.cpp
+++ b/forth/Forth.cpp
@@ -1,7 +1,8 @@
#include "Forth.h"
+#include "ForthParser.h"
#include "SkTDArray.h"
-#include "SkTDict.h"
#include "SkString.h"
+#include "SkTDStack.h"
ForthEngine::ForthEngine(ForthOutput* output) : fOutput(output) {
size_t size = 32 * sizeof(intptr_t);
@@ -22,8 +23,6 @@
}
}
-///////////////// ints
-
void ForthEngine::push(intptr_t value) {
if (fStackCurr > fStackBase) {
SkASSERT(fStackCurr <= fStackStop && fStackCurr > fStackBase);
@@ -66,13 +65,19 @@
void ForthWord::call(ForthCallBlock* block) {
ForthEngine engine(NULL);
+
+ // setup the initial stack with the callers input data
if (block) {
// walk the array backwards, so that the top of the stack is data[0]
for (size_t i = 0; i < block->in_count; i++) {
engine.push(block->in_data[i]);
}
}
+
+ // now invoke the word
this->exec(&engine);
+
+ // now copy back the stack into the caller's output data
if (block) {
size_t n = engine.depth();
block->out_depth = n;
@@ -87,220 +92,6 @@
///////////////////////////////////////////////////////////////////////////////
-class drop_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- (void)fe->pop();
- }
-};
-
-class clearStack_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- fe->clearStack();
- }
-};
-
-class dup_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- fe->push(fe->top());
- }
-};
-
-class swap_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- int32_t a = fe->pop();
- int32_t b = fe->top();
- fe->setTop(a);
- fe->push(b);
- }
-};
-
-///////////////// ints
-
-class add_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- intptr_t tmp = fe->pop();
- fe->setTop(fe->top() + tmp);
- }
-};
-
-class sub_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- intptr_t tmp = fe->pop();
- fe->setTop(fe->top() - tmp);
- }
-};
-
-class mul_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- intptr_t tmp = fe->pop();
- fe->setTop(fe->top() * tmp);
- }
-};
-
-class div_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- intptr_t tmp = fe->pop();
- fe->setTop(fe->top() / tmp);
- }
-};
-
-class dot_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- SkString str;
- str.printf("%d ", fe->pop());
- fe->sendOutput(str.c_str());
- }
-};
-
-class abs_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- int32_t value = fe->top();
- if (value < 0) {
- fe->setTop(-value);
- }
- }
-};
-
-class min_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- int32_t value = fe->pop();
- if (value < fe->top()) {
- fe->setTop(value);
- }
- }
-};
-
-class max_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- int32_t value = fe->pop();
- if (value > fe->top()) {
- fe->setTop(value);
- }
- }
-};
-
-///////////////// floats
-
-class fadd_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- float tmp = fe->fpop();
- fe->fsetTop(fe->ftop() + tmp);
- }
-};
-
-class fsub_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- float tmp = fe->fpop();
- fe->fsetTop(fe->ftop() - tmp);
- }
-};
-
-class fmul_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- float tmp = fe->fpop();
- fe->fsetTop(fe->ftop() * tmp);
- }
-};
-
-class fdiv_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- float tmp = fe->fpop();
- fe->fsetTop(fe->ftop() / tmp);
- }
-};
-
-class fdot_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- SkString str;
- str.printf("%g ", fe->fpop());
- fe->sendOutput(str.c_str());
- }
-};
-
-class fabs_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- float value = fe->ftop();
- if (value < 0) {
- fe->fsetTop(-value);
- }
- }
-};
-
-class fmin_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- float value = fe->fpop();
- if (value < fe->ftop()) {
- fe->fsetTop(value);
- }
- }
-};
-
-class fmax_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- float value = fe->fpop();
- if (value > fe->ftop()) {
- fe->fsetTop(value);
- }
- }
-};
-
-class floor_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- fe->fsetTop(floorf(fe->ftop()));
- }
-};
-
-class ceil_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- fe->fsetTop(ceilf(fe->ftop()));
- }
-};
-
-class round_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- fe->fsetTop(floorf(fe->ftop() + 0.5f));
- }
-};
-
-class f2i_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- fe->setTop((int)fe->ftop());
- }
-};
-
-class i2f_ForthWord : public ForthWord {
-public:
- virtual void exec(ForthEngine* fe) {
- fe->fsetTop((float)fe->top());
- }
-};
-
-///////////////////////////////////////////////////////////////////////////////
-
/*
reading an initial 32bit value from the code stream:
@@ -317,22 +108,40 @@
class FCode {
public:
+ enum {
+ kCodeShift = 2,
+ kCodeMask = 7,
+ kCodeDataShift = 5
+ };
+ static unsigned GetCode(intptr_t c) {
+ return ((uint32_t)c >> kCodeShift) & kCodeMask;
+ }
+ static unsigned GetCodeData(intptr_t c) {
+ return (uint32_t)c >> kCodeDataShift;
+ }
+
enum Bits {
kWord_Bits = 0, // must be zero for function address
kDataClear2_Bits = 1,
kDataShift2_Bits = 2,
kCodeShift2_Bits = 3
};
+
enum Code {
- kPushInt_Code,
+ kPushInt_Code, // for data that needs more than 30 bits
+ kIF_Code,
+ kELSE_Code,
kDone_Code
};
-
+ static unsigned MakeCode(Code code) {
+ return (code << kCodeShift) | kCodeShift2_Bits;
+ }
+
void appendInt(int32_t);
void appendWord(ForthWord*);
- void appendIF() {}
- bool appendELSE() { return false; }
- bool appendTHEN() { return false; }
+ void appendIF();
+ bool appendELSE();
+ bool appendTHEN();
void done();
intptr_t* detach() {
@@ -348,13 +157,14 @@
private:
SkTDArray<intptr_t> fData;
+ SkTDStack<size_t> fIfStack;
};
void FCode::appendInt(int32_t value) {
if ((value & 3) == 0) {
*fData.append() = value | kDataClear2_Bits;
- } else if ((value >> 2 << 2) == value) {
- *fData.append() = value | kDataShift2_Bits;
+ } else if ((value << 2 >> 2) == value) {
+ *fData.append() = (value << 2) | kDataShift2_Bits;
} else {
intptr_t* p = fData.append(2);
*p++ = (kPushInt_Code << 2) | kCodeShift2_Bits;
@@ -367,6 +177,43 @@
*fData.append() = reinterpret_cast<intptr_t>(word);
}
+void FCode::appendIF() {
+ size_t ifIndex = fData.count();
+ fIfStack.push(ifIndex);
+ *fData.append() = MakeCode(kIF_Code);
+}
+
+bool FCode::appendELSE() {
+ if (fIfStack.empty()) {
+ return false;
+ }
+
+ size_t elseIndex = fData.count();
+ *fData.append() = MakeCode(kELSE_Code);
+
+ size_t ifIndex = fIfStack.top();
+ // record the offset in the data part of the if-code
+ fData[ifIndex] |= (elseIndex - ifIndex) << kCodeDataShift;
+
+ // now reuse this IfStack entry to track the else
+ fIfStack.top() = elseIndex;
+ return true;
+}
+
+bool FCode::appendTHEN() {
+ if (fIfStack.empty()) {
+ return false;
+ }
+
+ // this is either an IF or an ELSE
+ size_t index = fIfStack.top();
+ // record the offset in the data part of the code
+ fData[index] |= (fData.count() - index - 1) << kCodeDataShift;
+
+ fIfStack.pop();
+ return true;
+}
+
void FCode::done() {
*fData.append() = (kDone_Code << 2) | kCodeShift2_Bits;
}
@@ -385,10 +232,20 @@
engine->push(c >> 2);
break;
case kCodeShift2_Bits:
- switch ((uint32_t)c >> 2) {
+ switch (GetCode(c)) {
case kPushInt_Code:
engine->push(*curr++);
break;
+ case kIF_Code:
+ if (!engine->pop()) {
+ // takes us past the ELSE or THEN
+ curr += GetCodeData(c);
+ }
+ break;
+ case kELSE_Code:
+ // takes us past the THEN
+ curr += GetCodeData(c);
+ break;
case kDone_Code:
return;
}
@@ -415,61 +272,12 @@
///////////////////////////////////////////////////////////////////////////////
-class ForthParser {
-public:
- ForthParser() : fDict(4096) {
- this->addStdWords();
- }
+ForthParser::ForthParser() : fDict(4096) {
+ this->addStdWords();
+}
- const char* parse(const char text[], FCode*);
-
- void addWord(const char name[], ForthWord* word) {
- this->add(name, strlen(name), word);
- }
-
- ForthWord* find(const char name[], size_t len) const {
- ForthWord* word;
- return fDict.find(name, len, &word) ? word : NULL;
- }
-
-private:
- void add(const char name[], size_t len, ForthWord* word) {
- (void)fDict.set(name, len, word);
- }
-
- void addStdWords() {
- this->add("clr", 3, new clearStack_ForthWord);
- this->add("drop", 4, new drop_ForthWord);
- this->add("dup", 3, new dup_ForthWord);
- this->add("swap", 4, new swap_ForthWord);
-
- this->add("+", 1, new add_ForthWord);
- this->add("-", 1, new sub_ForthWord);
- this->add("*", 1, new mul_ForthWord);
- this->add("/", 1, new div_ForthWord);
- this->add(".", 1, new dot_ForthWord);
- this->add("abs", 3, new abs_ForthWord);
- this->add("min", 3, new min_ForthWord);
- this->add("max", 3, new max_ForthWord);
-
- this->add("f+", 2, new fadd_ForthWord);
- this->add("f-", 2, new fsub_ForthWord);
- this->add("f*", 2, new fmul_ForthWord);
- this->add("f/", 2, new fdiv_ForthWord);
- this->add("f.", 2, new fdot_ForthWord);
- this->add("fabs", 4, new fabs_ForthWord);
- this->add("fmin", 4, new fmin_ForthWord);
- this->add("fmax", 4, new fmax_ForthWord);
- this->add("fmax", 4, new fmax_ForthWord);
- this->add("floor", 5, new floor_ForthWord);
- this->add("ceil", 4, new ceil_ForthWord);
- this->add("round", 5, new round_ForthWord);
- this->add("f>i", 3, new f2i_ForthWord);
- this->add("i>f", 3, new i2f_ForthWord);
- }
-
- SkTDict<ForthWord*> fDict;
-};
+ForthParser::~ForthParser() {
+}
static const char* parse_error(const char msg[]) {
SkDebugf("-- parser error: %s\n", msg);
@@ -615,11 +423,11 @@
code->appendInt(num);
} else if (2 == len && memcmp(token, "IF", 2) == 0) {
code->appendIF();
- } else if (2 == len && memcmp(token, "ELSE", 4) == 0) {
+ } else if (4 == len && memcmp(token, "ELSE", 4) == 0) {
if (!code->appendELSE()) {
return parse_error("ELSE with no matching IF");
}
- } else if (2 == len && memcmp(token, "THEN", 4) == 0) {
+ } else if (4 == len && memcmp(token, "THEN", 4) == 0) {
if (!code->appendTHEN()) {
return parse_error("THEN with no matching IF");
}