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AP_HAL: ftoa_engine: replace tabs with spaces
This commit is contained in:
Lucas De Marchi
parent
e751d632e6
commit
29ed01189d
@ -44,186 +44,186 @@
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* e = exponentTable[i]
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*/
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static const int8_t exponentTable[32] = {
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-36, -33, -31, -29, -26, -24, -21, -19,
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-17, -14, -12, -9, -7, -4, -2, 0,
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3, 5, 8, 10, 12, 15, 17, 20,
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22, 24, 27, 29, 32, 34, 36, 39
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-36, -33, -31, -29, -26, -24, -21, -19,
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-17, -14, -12, -9, -7, -4, -2, 0,
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3, 5, 8, 10, 12, 15, 17, 20,
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22, 24, 27, 29, 32, 34, 36, 39
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};
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static const uint32_t factorTable[32] = {
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2295887404UL,
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587747175UL,
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1504632769UL,
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3851859889UL,
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986076132UL,
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2524354897UL,
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646234854UL,
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1654361225UL,
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4235164736UL,
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1084202172UL,
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2775557562UL,
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710542736UL,
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1818989404UL,
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465661287UL,
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1192092896UL,
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3051757813UL,
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781250000UL,
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2000000000UL,
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512000000UL,
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1310720000UL,
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3355443200UL,
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858993459UL,
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2199023256UL,
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562949953UL,
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1441151881UL,
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3689348815UL,
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944473297UL,
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2417851639UL,
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618970020UL,
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1584563250UL,
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4056481921UL,
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1038459372UL
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2295887404UL,
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587747175UL,
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1504632769UL,
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3851859889UL,
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986076132UL,
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2524354897UL,
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646234854UL,
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1654361225UL,
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4235164736UL,
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1084202172UL,
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2775557562UL,
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710542736UL,
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1818989404UL,
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465661287UL,
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1192092896UL,
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3051757813UL,
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781250000UL,
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2000000000UL,
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512000000UL,
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1310720000UL,
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3355443200UL,
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858993459UL,
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2199023256UL,
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562949953UL,
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1441151881UL,
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3689348815UL,
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944473297UL,
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2417851639UL,
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618970020UL,
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1584563250UL,
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4056481921UL,
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1038459372UL
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};
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int16_t ftoa_engine(float val, char *buf, uint8_t precision, uint8_t maxDecimals)
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{
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uint8_t flags;
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uint8_t flags;
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// Bit reinterpretation hacks. This will ONLY work on little endian machines.
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uint8_t *valbits = (uint8_t*)&val;
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union {
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float v;
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uint32_t u;
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} x;
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x.v = val;
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uint32_t frac = x.u & 0x007fffffUL;
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// Bit reinterpretation hacks. This will ONLY work on little endian machines.
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uint8_t *valbits = (uint8_t*)&val;
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union {
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float v;
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uint32_t u;
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} x;
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x.v = val;
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uint32_t frac = x.u & 0x007fffffUL;
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if (precision>7) precision=7;
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if (precision>7) precision=7;
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// Read the sign, shift the exponent in place and delete it from frac.
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if (valbits[3] & (1<<7)) flags = FTOA_MINUS; else flags = 0;
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uint8_t exp = valbits[3]<<1;
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if(valbits[2] & (1<<7)) exp++; // TODO possible but in case of subnormal
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// Read the sign, shift the exponent in place and delete it from frac.
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if (valbits[3] & (1<<7)) flags = FTOA_MINUS; else flags = 0;
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uint8_t exp = valbits[3]<<1;
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if(valbits[2] & (1<<7)) exp++; // TODO possible but in case of subnormal
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// Test for easy cases, zero and NaN
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if(exp==0 && frac==0) {
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buf[0] = flags | FTOA_ZERO;
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uint8_t i;
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for(i=0; i<=precision; i++) {
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buf[i+1] = '0';
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}
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return 0;
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}
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// Test for easy cases, zero and NaN
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if(exp==0 && frac==0) {
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buf[0] = flags | FTOA_ZERO;
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uint8_t i;
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for(i=0; i<=precision; i++) {
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buf[i+1] = '0';
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}
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return 0;
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}
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if(exp == 0xff) {
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if(frac == 0) flags |= FTOA_INF; else flags |= FTOA_NAN;
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}
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if(exp == 0xff) {
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if(frac == 0) flags |= FTOA_INF; else flags |= FTOA_NAN;
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}
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// The implicit leading 1 is made explicit, except if value subnormal.
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if (exp != 0) frac |= (1UL<<23);
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// The implicit leading 1 is made explicit, except if value subnormal.
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if (exp != 0) frac |= (1UL<<23);
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uint8_t idx = exp>>3;
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int8_t exp10 = exponentTable[idx];
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uint8_t idx = exp>>3;
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int8_t exp10 = exponentTable[idx];
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// We COULD try making the multiplication in situ, where we make
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// frac and a 64 bit int overlap in memory and select/weigh the
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// upper 32 bits that way. For starters, this is less risky:
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int64_t prod = (int64_t)frac * (int64_t)factorTable[idx];
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// We COULD try making the multiplication in situ, where we make
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// frac and a 64 bit int overlap in memory and select/weigh the
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// upper 32 bits that way. For starters, this is less risky:
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int64_t prod = (int64_t)frac * (int64_t)factorTable[idx];
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// The expConvFactorTable are factor are correct iff the lower 3 exponent
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// bits are 1 (=7). Else we need to compensate by divding frac.
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// If the lower 3 bits are 7 we are right.
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// If the lower 3 bits are 6 we right-shift once
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// ..
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// If the lower 3 bits are 0 we right-shift 7x
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prod >>= (15-(exp & 7));
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// The expConvFactorTable are factor are correct iff the lower 3 exponent
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// bits are 1 (=7). Else we need to compensate by divding frac.
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// If the lower 3 bits are 7 we are right.
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// If the lower 3 bits are 6 we right-shift once
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// ..
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// If the lower 3 bits are 0 we right-shift 7x
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prod >>= (15-(exp & 7));
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// Now convert to decimal.
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uint8_t hadNonzeroDigit = 0; // a flag
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uint8_t outputIdx = 0;
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int64_t decimal = 100000000000000ull;
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// Now convert to decimal.
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uint8_t hadNonzeroDigit = 0; // a flag
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uint8_t outputIdx = 0;
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int64_t decimal = 100000000000000ull;
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do {
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char digit = '0';
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while(1) {// find the first nonzero digit or any of the next digits.
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while ((prod -= decimal) >= 0)
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digit++;
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// Now we got too low. Fix it by adding again, once.
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// it might appear more efficient to check before subtract, or
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// to save and restore last nonnegative value - but in fact
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// they take as long time and more space.
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prod += decimal;
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decimal /= 10;
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do {
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char digit = '0';
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while(1) {// find the first nonzero digit or any of the next digits.
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while ((prod -= decimal) >= 0)
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digit++;
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// Now we got too low. Fix it by adding again, once.
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// it might appear more efficient to check before subtract, or
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// to save and restore last nonnegative value - but in fact
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// they take as long time and more space.
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prod += decimal;
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decimal /= 10;
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// If already found a leading nonzero digit, accept zeros.
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if (hadNonzeroDigit) break;
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// If already found a leading nonzero digit, accept zeros.
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if (hadNonzeroDigit) break;
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// Else, don't return results with a leading zero! Instead
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// skip those and decrement exp10 accordingly.
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if(digit == '0') {
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exp10--;
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continue;
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}
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// Else, don't return results with a leading zero! Instead
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// skip those and decrement exp10 accordingly.
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if(digit == '0') {
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exp10--;
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continue;
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}
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hadNonzeroDigit = 1;
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hadNonzeroDigit = 1;
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// Compute how many digits N to output.
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if(maxDecimals != 0) { // If limiting decimals...
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int8_t beforeDP = exp10+1; // Digits before point
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if (beforeDP < 1) beforeDP = 1; // Numbers < 1 should also output at least 1 digit.
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/*
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* Below a simpler version of this:
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int8_t afterDP = outputNum - beforeDP;
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if (afterDP > maxDecimals-1)
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afterDP = maxDecimals-1;
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outputNum = beforeDP + afterDP;
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*/
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maxDecimals = maxDecimals+beforeDP-1;
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if (precision > maxDecimals)
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precision = maxDecimals;
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// Compute how many digits N to output.
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if(maxDecimals != 0) { // If limiting decimals...
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int8_t beforeDP = exp10+1; // Digits before point
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if (beforeDP < 1) beforeDP = 1; // Numbers < 1 should also output at least 1 digit.
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/*
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* Below a simpler version of this:
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int8_t afterDP = outputNum - beforeDP;
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if (afterDP > maxDecimals-1)
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afterDP = maxDecimals-1;
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outputNum = beforeDP + afterDP;
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*/
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maxDecimals = maxDecimals+beforeDP-1;
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if (precision > maxDecimals)
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precision = maxDecimals;
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} else {
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precision++; // Output one more digit than the param value.
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}
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} else {
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precision++; // Output one more digit than the param value.
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}
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break;
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}
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break;
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}
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// Now have a digit.
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outputIdx++;
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if(digit < '0' + 10) // normal case.
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buf[outputIdx] = digit;
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else {
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// Abnormal case, write 9s and bail.
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// We might as well abuse hadNonzeroDigit as counter, it will not be used again.
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for(hadNonzeroDigit=outputIdx; hadNonzeroDigit>0; hadNonzeroDigit--)
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buf[hadNonzeroDigit] = '9';
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goto roundup; // this is ugly but it _is_ code derived from assembler :)
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}
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} while (outputIdx<precision);
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// Now have a digit.
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outputIdx++;
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if(digit < '0' + 10) // normal case.
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buf[outputIdx] = digit;
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else {
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// Abnormal case, write 9s and bail.
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// We might as well abuse hadNonzeroDigit as counter, it will not be used again.
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for(hadNonzeroDigit=outputIdx; hadNonzeroDigit>0; hadNonzeroDigit--)
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buf[hadNonzeroDigit] = '9';
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goto roundup; // this is ugly but it _is_ code derived from assembler :)
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}
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} while (outputIdx<precision);
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// Rounding:
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decimal *= 10;
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// Rounding:
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decimal *= 10;
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if (prod - (decimal >> 1) >= 0) {
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if (prod - (decimal >> 1) >= 0) {
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roundup:
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// Increment digit, cascade
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while(outputIdx != 0) {
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if(++buf[outputIdx] == '0' + 10) {
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if(outputIdx == 1) {
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buf[outputIdx] = '1';
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exp10++;
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flags |= FTOA_CARRY;
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break;
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} else
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buf[outputIdx--] = '0'; // and the loop continues, carrying to next digit.
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}
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else break;
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}
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}
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roundup:
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// Increment digit, cascade
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while(outputIdx != 0) {
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if(++buf[outputIdx] == '0' + 10) {
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if(outputIdx == 1) {
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buf[outputIdx] = '1';
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exp10++;
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flags |= FTOA_CARRY;
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break;
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} else
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buf[outputIdx--] = '0'; // and the loop continues, carrying to next digit.
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}
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else break;
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}
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}
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buf[0] = flags;
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return exp10;
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buf[0] = flags;
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return exp10;
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}
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