py/formatfloat: Fix rounding of %f format with edge-case FP values.

Prior to this patch the %f formatting of some FP values could be off by up
to 1, eg '%.0f' % 123 would return "122" (unix x64).  Depending on the FP
precision (single vs double) certain numbers would format correctly, but
others wolud not.  This patch should fix all cases of rounding for %f.
This commit is contained in:
Damien George 2018-03-01 15:47:17 +11:00
parent 90e719a232
commit bc12eca461
3 changed files with 13 additions and 2 deletions

View File

@ -341,7 +341,7 @@ int mp_format_float(FPTYPE f, char *buf, size_t buf_size, char fmt, int prec, ch
// Round
// If we print non-exponential format (i.e. 'f'), but a digit we're going
// to round by (e) is too far away, then there's nothing to round.
if ((org_fmt != 'f' || e <= 1) && f >= FPCONST(5.0)) {
if ((org_fmt != 'f' || e <= num_digits) && f >= FPCONST(5.0)) {
char *rs = s;
rs--;
while (1) {

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@ -0,0 +1,11 @@
# test float formatting
# general rounding
for val in (116, 1111, 1234, 5010, 11111):
print('%.0f' % val)
print('%.1f' % val)
print('%.3f' % val)
# make sure rounding is done at the correct precision
for prec in range(8):
print(('%%.%df' % prec) % 6e-5)

View File

@ -56,7 +56,7 @@ Warning: test
+1e+00
+1e+00
# binary
122
123
456
# VM
2 1