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Refactor print receiver to calculate checksums and raise CRC error when necessary

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This commit is contained in:
XANTRONIX Development 2016-06-07 17:59:23 -05:00
parent eb8ac6acb6
commit 5b27cf9c79
1 changed files with 28 additions and 4 deletions
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32
avr/recv.c
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@ -9,7 +9,14 @@
static volatile uint16_t offset_header = 0,
offset_body = 0,
size_body = 0;
size_body = 0,
sum_calc = 0,
sum_footer = 0;
static volatile tabby_printer_response response = {
.device = TABBY_PRINTER_DEVICE_ID,
.status = TABBY_PRINTER_OK
};
/*
* SPI byte receipt interrupt vector
@ -25,6 +32,9 @@ ISR(SPI_STC_vect) {
if (in == TABBY_PRINTER_SYNC_1) {
offset_header++;
offset_body = 0;
sum_calc = 0;
response.status = TABBY_PRINTER_OK;
}
break;
@ -43,6 +53,7 @@ ISR(SPI_STC_vect) {
case 2:
case 3: {
offset_header++;
sum_calc += in;
break;
}
@ -50,6 +61,7 @@ ISR(SPI_STC_vect) {
case 4: {
size_body = in;
sum_calc += in;
offset_header++;
break;
@ -64,20 +76,32 @@ ISR(SPI_STC_vect) {
offset_header++;
}
sum_calc += in;
break;
}
default: {
if (offset_body <= size_body) {
if (offset_body < size_body) {
offset_body++;
sum_calc += in;
} else if (offset_body == size_body) {
offset_body++;
sum_footer = in;
} else if (offset_body == size_body + 1) {
offset_body++;
out = TABBY_PRINTER_DEVICE_ID;
sum_footer |= in << 8;
if (sum_footer != sum_calc) {
response.status |= TABBY_PRINTER_SUM;
}
out = response.device;
} else if (offset_body == size_body + 2) {
offset_body++;
out = TABBY_PRINTER_OK;
out = response.status;
} else if (offset_body == size_body + 3) {
offset_header = 0;
}