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AP_HAL: ftoa_engine: replace tabs with spaces

mission-4.1.18
Lucas De Marchi 9 years ago
parent
e751d632e6
commit
29ed01189d
1 changed files with 174 additions and 174 deletions
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  1. 348
      libraries/AP_HAL/utility/ftoa_engine.cpp

348
libraries/AP_HAL/utility/ftoa_engine.cpp
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@ -44,186 +44,186 @@ @@ -44,186 +44,186 @@
* e = exponentTable[i]
*/
static const int8_t exponentTable[32] = {
-36, -33, -31, -29, -26, -24, -21, -19,
-17, -14, -12, -9, -7, -4, -2, 0,
3, 5, 8, 10, 12, 15, 17, 20,
22, 24, 27, 29, 32, 34, 36, 39
-36, -33, -31, -29, -26, -24, -21, -19,
-17, -14, -12, -9, -7, -4, -2, 0,
3, 5, 8, 10, 12, 15, 17, 20,
22, 24, 27, 29, 32, 34, 36, 39
};
static const uint32_t factorTable[32] = {
2295887404UL,
587747175UL,
1504632769UL,
3851859889UL,
986076132UL,
2524354897UL,
646234854UL,
1654361225UL,
4235164736UL,
1084202172UL,
2775557562UL,
710542736UL,
1818989404UL,
465661287UL,
1192092896UL,
3051757813UL,
781250000UL,
2000000000UL,
512000000UL,
1310720000UL,
3355443200UL,
858993459UL,
2199023256UL,
562949953UL,
1441151881UL,
3689348815UL,
944473297UL,
2417851639UL,
618970020UL,
1584563250UL,
4056481921UL,
1038459372UL
2295887404UL,
587747175UL,
1504632769UL,
3851859889UL,
986076132UL,
2524354897UL,
646234854UL,
1654361225UL,
4235164736UL,
1084202172UL,
2775557562UL,
710542736UL,
1818989404UL,
465661287UL,
1192092896UL,
3051757813UL,
781250000UL,
2000000000UL,
512000000UL,
1310720000UL,
3355443200UL,
858993459UL,
2199023256UL,
562949953UL,
1441151881UL,
3689348815UL,
944473297UL,
2417851639UL,
618970020UL,
1584563250UL,
4056481921UL,
1038459372UL
};
int16_t ftoa_engine(float val, char *buf, uint8_t precision, uint8_t maxDecimals)
{
uint8_t flags;
// Bit reinterpretation hacks. This will ONLY work on little endian machines.
uint8_t *valbits = (uint8_t*)&val;
union {
float v;
uint32_t u;
} x;
x.v = val;
uint32_t frac = x.u & 0x007fffffUL;
if (precision>7) precision=7;
// Read the sign, shift the exponent in place and delete it from frac.
if (valbits[3] & (1<<7)) flags = FTOA_MINUS; else flags = 0;
uint8_t exp = valbits[3]<<1;
if(valbits[2] & (1<<7)) exp++; // TODO possible but in case of subnormal
// Test for easy cases, zero and NaN
if(exp==0 && frac==0) {
buf[0] = flags | FTOA_ZERO;
uint8_t i;
for(i=0; i<=precision; i++) {
buf[i+1] = '0';
}
return 0;
}
if(exp == 0xff) {
if(frac == 0) flags |= FTOA_INF; else flags |= FTOA_NAN;
}
// The implicit leading 1 is made explicit, except if value subnormal.
if (exp != 0) frac |= (1UL<<23);
uint8_t idx = exp>>3;
int8_t exp10 = exponentTable[idx];
// We COULD try making the multiplication in situ, where we make
// frac and a 64 bit int overlap in memory and select/weigh the
// upper 32 bits that way. For starters, this is less risky:
int64_t prod = (int64_t)frac * (int64_t)factorTable[idx];
// The expConvFactorTable are factor are correct iff the lower 3 exponent
// bits are 1 (=7). Else we need to compensate by divding frac.
// If the lower 3 bits are 7 we are right.
// If the lower 3 bits are 6 we right-shift once
// ..
// If the lower 3 bits are 0 we right-shift 7x
prod >>= (15-(exp & 7));
// Now convert to decimal.
uint8_t hadNonzeroDigit = 0; // a flag
uint8_t outputIdx = 0;
int64_t decimal = 100000000000000ull;
do {
char digit = '0';
while(1) {// find the first nonzero digit or any of the next digits.
while ((prod -= decimal) >= 0)
digit++;
// Now we got too low. Fix it by adding again, once.
// it might appear more efficient to check before subtract, or
// to save and restore last nonnegative value - but in fact
// they take as long time and more space.
prod += decimal;
decimal /= 10;
// If already found a leading nonzero digit, accept zeros.
if (hadNonzeroDigit) break;
// Else, don't return results with a leading zero! Instead
// skip those and decrement exp10 accordingly.
if(digit == '0') {
exp10--;
continue;
}
hadNonzeroDigit = 1;
// Compute how many digits N to output.
if(maxDecimals != 0) { // If limiting decimals...
int8_t beforeDP = exp10+1; // Digits before point
if (beforeDP < 1) beforeDP = 1; // Numbers < 1 should also output at least 1 digit.
/*
* Below a simpler version of this:
int8_t afterDP = outputNum - beforeDP;
if (afterDP > maxDecimals-1)
afterDP = maxDecimals-1;
outputNum = beforeDP + afterDP;
*/
maxDecimals = maxDecimals+beforeDP-1;
if (precision > maxDecimals)
precision = maxDecimals;
} else {
precision++; // Output one more digit than the param value.
}
break;
}
// Now have a digit.
outputIdx++;
if(digit < '0' + 10) // normal case.
buf[outputIdx] = digit;
else {
// Abnormal case, write 9s and bail.
// We might as well abuse hadNonzeroDigit as counter, it will not be used again.
for(hadNonzeroDigit=outputIdx; hadNonzeroDigit>0; hadNonzeroDigit--)
buf[hadNonzeroDigit] = '9';
goto roundup; // this is ugly but it _is_ code derived from assembler :)
}
} while (outputIdx<precision);
// Rounding:
decimal *= 10;
if (prod - (decimal >> 1) >= 0) {
roundup:
// Increment digit, cascade
while(outputIdx != 0) {
if(++buf[outputIdx] == '0' + 10) {
if(outputIdx == 1) {
buf[outputIdx] = '1';
exp10++;
flags |= FTOA_CARRY;
break;
} else
buf[outputIdx--] = '0'; // and the loop continues, carrying to next digit.
}
else break;
}
}
buf[0] = flags;
return exp10;
uint8_t flags;
// Bit reinterpretation hacks. This will ONLY work on little endian machines.
uint8_t *valbits = (uint8_t*)&val;
union {
float v;
uint32_t u;
} x;
x.v = val;
uint32_t frac = x.u & 0x007fffffUL;
if (precision>7) precision=7;
// Read the sign, shift the exponent in place and delete it from frac.
if (valbits[3] & (1<<7)) flags = FTOA_MINUS; else flags = 0;
uint8_t exp = valbits[3]<<1;
if(valbits[2] & (1<<7)) exp++; // TODO possible but in case of subnormal
// Test for easy cases, zero and NaN
if(exp==0 && frac==0) {
buf[0] = flags | FTOA_ZERO;
uint8_t i;
for(i=0; i<=precision; i++) {
buf[i+1] = '0';
}
return 0;
}
if(exp == 0xff) {
if(frac == 0) flags |= FTOA_INF; else flags |= FTOA_NAN;
}
// The implicit leading 1 is made explicit, except if value subnormal.
if (exp != 0) frac |= (1UL<<23);
uint8_t idx = exp>>3;
int8_t exp10 = exponentTable[idx];
// We COULD try making the multiplication in situ, where we make
// frac and a 64 bit int overlap in memory and select/weigh the
// upper 32 bits that way. For starters, this is less risky:
int64_t prod = (int64_t)frac * (int64_t)factorTable[idx];
// The expConvFactorTable are factor are correct iff the lower 3 exponent
// bits are 1 (=7). Else we need to compensate by divding frac.
// If the lower 3 bits are 7 we are right.
// If the lower 3 bits are 6 we right-shift once
// ..
// If the lower 3 bits are 0 we right-shift 7x
prod >>= (15-(exp & 7));
// Now convert to decimal.
uint8_t hadNonzeroDigit = 0; // a flag
uint8_t outputIdx = 0;
int64_t decimal = 100000000000000ull;
do {
char digit = '0';
while(1) {// find the first nonzero digit or any of the next digits.
while ((prod -= decimal) >= 0)
digit++;
// Now we got too low. Fix it by adding again, once.
// it might appear more efficient to check before subtract, or
// to save and restore last nonnegative value - but in fact
// they take as long time and more space.
prod += decimal;
decimal /= 10;
// If already found a leading nonzero digit, accept zeros.
if (hadNonzeroDigit) break;
// Else, don't return results with a leading zero! Instead
// skip those and decrement exp10 accordingly.
if(digit == '0') {
exp10--;
continue;
}
hadNonzeroDigit = 1;
// Compute how many digits N to output.
if(maxDecimals != 0) { // If limiting decimals...
int8_t beforeDP = exp10+1; // Digits before point
if (beforeDP < 1) beforeDP = 1; // Numbers < 1 should also output at least 1 digit.
/*
* Below a simpler version of this:
int8_t afterDP = outputNum - beforeDP;
if (afterDP > maxDecimals-1)
afterDP = maxDecimals-1;
outputNum = beforeDP + afterDP;
*/
maxDecimals = maxDecimals+beforeDP-1;
if (precision > maxDecimals)
precision = maxDecimals;
} else {
precision++; // Output one more digit than the param value.
}
break;
}
// Now have a digit.
outputIdx++;
if(digit < '0' + 10) // normal case.
buf[outputIdx] = digit;
else {
// Abnormal case, write 9s and bail.
// We might as well abuse hadNonzeroDigit as counter, it will not be used again.
for(hadNonzeroDigit=outputIdx; hadNonzeroDigit>0; hadNonzeroDigit--)
buf[hadNonzeroDigit] = '9';
goto roundup; // this is ugly but it _is_ code derived from assembler :)
}
} while (outputIdx<precision);
// Rounding:
decimal *= 10;
if (prod - (decimal >> 1) >= 0) {
roundup:
// Increment digit, cascade
while(outputIdx != 0) {
if(++buf[outputIdx] == '0' + 10) {
if(outputIdx == 1) {
buf[outputIdx] = '1';
exp10++;
flags |= FTOA_CARRY;
break;
} else
buf[outputIdx--] = '0'; // and the loop continues, carrying to next digit.
}
else break;
}
}
buf[0] = flags;
return exp10;
}

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