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Counteract inaccuracy of float values in look ahead test

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Bug report by brunt, ticket #49
This commit is contained in:
Robin Stuart 2016-11-26 13:58:54 +00:00
parent 08aefa6aea
commit 0dc3b60c2b
1 changed files with 38 additions and 36 deletions
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74
backend/dmatrix.c
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@ -304,6 +304,7 @@ static int p_r_6_2_1(const unsigned char inputData[], const int position, const
/* 'look ahead test' from Annex P */
static int look_ahead_test(const unsigned char inputData[], const int sourcelen, const int position, const int current_mode, const int gs1) {
float ascii_count, c40_count, text_count, x12_count, edf_count, b256_count, best_count;
const float stiction = (1.0F / 24.0F); // smallest change to act on, to get around floating point inaccuracies
int sp, best_scheme;
best_scheme = DM_NULL;
@ -353,27 +354,27 @@ static int look_ahead_test(const unsigned char inputData[], const int sourcelen,
best_count = c40_count;
best_scheme = DM_C40; // (k)(7)
if (x12_count < best_count) {
if (x12_count < (best_count - stiction)) {
best_count = x12_count;
best_scheme = DM_X12; // (k)(6)
}
if (text_count < best_count) {
if (text_count < (best_count - stiction)) {
best_count = text_count;
best_scheme = DM_TEXT; // (k)(5)
}
if (edf_count < best_count) {
if (edf_count < (best_count - stiction)) {
best_count = edf_count;
best_scheme = DM_EDIFACT; // (k)(4)
}
if (b256_count < best_count) {
if (b256_count < (best_count - stiction)) {
best_count = b256_count;
best_scheme = DM_BASE256; // (k)(3)
}
if (ascii_count <= best_count) {
if (ascii_count <= (best_count + stiction)) {
best_scheme = DM_ASCII; // (k)(2)
}
} else {
@ -453,16 +454,17 @@ static int look_ahead_test(const unsigned char inputData[], const int sourcelen,
/* 4 data characters processed ... step (r) */
/* step (r)(6) */
if (((c40_count + 1.0F) < ascii_count) &&
((c40_count + 1.0F) < b256_count) &&
((c40_count + 1.0F) < edf_count) &&
((c40_count + 1.0F) < text_count)) {
if (((c40_count + 1.0F) < (ascii_count - stiction)) &&
((c40_count + 1.0F) < (b256_count - stiction)) &&
((c40_count + 1.0F) < (edf_count - stiction)) &&
((c40_count + 1.0F) < (text_count - stiction))) {
if (c40_count < x12_count) {
if (c40_count < (x12_count - stiction)) {
best_scheme = DM_C40;
}
if (c40_count == x12_count) {
if ((c40_count >= (x12_count - stiction))
&& (c40_count <= (x12_count + stiction))) {
if (p_r_6_2_1(inputData, sp, sourcelen) == 1) {
// Test (r)(6)(ii)(i)
best_scheme = DM_X12;
@ -473,47 +475,47 @@ static int look_ahead_test(const unsigned char inputData[], const int sourcelen,
}
/* step (r)(5) */
if (((x12_count + 1.0F) < ascii_count) &&
((x12_count + 1.0F) < b256_count) &&
((x12_count + 1.0F) < edf_count) &&
((x12_count + 1.0F) < text_count) &&
((x12_count + 1.0F) < c40_count)) {
if (((x12_count + 1.0F) < (ascii_count - stiction)) &&
((x12_count + 1.0F) < (b256_count - stiction)) &&
((x12_count + 1.0F) < (edf_count - stiction)) &&
((x12_count + 1.0F) < (text_count - stiction)) &&
((x12_count + 1.0F) < (c40_count - stiction))) {
best_scheme = DM_X12;
}
/* step (r)(4) */
if (((text_count + 1.0F) < ascii_count) &&
((text_count + 1.0F) < b256_count) &&
((text_count + 1.0F) < edf_count) &&
((text_count + 1.0F) < x12_count) &&
((text_count + 1.0F) < c40_count)) {
if (((text_count + 1.0F) < (ascii_count - stiction)) &&
((text_count + 1.0F) < (b256_count - stiction)) &&
((text_count + 1.0F) < (edf_count - stiction)) &&
((text_count + 1.0F) < (x12_count - stiction)) &&
((text_count + 1.0F) < (c40_count - stiction))) {
best_scheme = DM_TEXT;
}
/* step (r)(3) */
if (((edf_count + 1.0F) < ascii_count) &&
((edf_count + 1.0F) < b256_count) &&
((edf_count + 1.0F) < text_count) &&
((edf_count + 1.0F) < x12_count) &&
((edf_count + 1.0F) < c40_count)) {
if (((edf_count + 1.0F) < (ascii_count - stiction)) &&
((edf_count + 1.0F) < (b256_count - stiction)) &&
((edf_count + 1.0F) < (text_count - stiction)) &&
((edf_count + 1.0F) < (x12_count - stiction)) &&
((edf_count + 1.0F) < (c40_count - stiction))) {
best_scheme = DM_EDIFACT;
}
/* step (r)(2) */
if (((b256_count + 1.0F) <= ascii_count) ||
(((b256_count + 1.0F) < edf_count) &&
((b256_count + 1.0F) < text_count) &&
((b256_count + 1.0F) < x12_count) &&
((b256_count + 1.0F) < c40_count))) {
if (((b256_count + 1.0F) <= (ascii_count + stiction)) ||
(((b256_count + 1.0F) < (edf_count - stiction)) &&
((b256_count + 1.0F) < (text_count - stiction)) &&
((b256_count + 1.0F) < (x12_count - stiction)) &&
((b256_count + 1.0F) < (c40_count - stiction)))) {
best_scheme = DM_BASE256;
}
/* step (r)(1) */
if (((ascii_count + 1.0F) <= b256_count) &&
((ascii_count + 1.0F) <= edf_count) &&
((ascii_count + 1.0F) <= text_count) &&
((ascii_count + 1.0F) <= x12_count) &&
((ascii_count + 1.0F) <= c40_count)) {
if (((ascii_count + 1.0F) <= (b256_count + stiction)) &&
((ascii_count + 1.0F) <= (edf_count + stiction)) &&
((ascii_count + 1.0F) <= (text_count + stiction)) &&
((ascii_count + 1.0F) <= (x12_count + stiction)) &&
((ascii_count + 1.0F) <= (c40_count + stiction))) {
best_scheme = DM_ASCII;
}
}