sf_emit_exp
sf_emit_exp(b, isupper((unsigned char)conv) ? 'E' : 'e', decpt - 1, 2);
sf_emit_exp(b, isupper((unsigned char)conv) ? 'E' : 'e',
sf_emit_exp(b, isupper((unsigned char)conv) ? 'P' : 'p', decpt - 1, 1);