67 lines
1.5 KiB
C
67 lines
1.5 KiB
C
/*
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* Copyright 2022 Oleg Borodin <borodin@unix7.org>
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*/
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#include <stdint.h>
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#include <stdbool.h>
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#include <string.h>
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#include <ibus.h>
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#define STARTFR_BYTE 0x20
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#define COMMAND_BYTE 0x40
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void ibus_init(ibus_t* bus) {
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memset(bus->iframe, 0, sizeof(bus->iframe));
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memset(bus->rcvalue, 0, sizeof(bus->rcvalue));
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bus->findex = 0;
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}
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bool ibus_recv(ibus_t* bus, uint8_t ibyte) {
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if(bus->findex == 0 && ibyte != STARTFR_BYTE) {
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return false;
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}
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if(bus->findex == 1 && ibyte != COMMAND_BYTE) {
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bus->findex = 0;
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return false;
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}
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if(bus->findex < IBUS_FRAMESIZE) {
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bus->iframe[bus->findex++] = ibyte;
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return false;
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}
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if(bus->findex == IBUS_FRAMESIZE) {
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bus->findex = 0;
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uint16_t chksum = 0xFFFF;
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for (int i = 0; i < 30; i++) {
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chksum -= bus->iframe[i];
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}
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uint16_t rxsum = bus->iframe[30] + (bus->iframe[31] << 8);
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if (chksum == rxsum) {
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for (int c = 0; c < IBUS_CHANNELS; c++) {
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int offset = c * 2 + 2;
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uint16_t hival = ((bus->iframe[offset + 1] & 0x0F) << 8);
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uint16_t loval = bus->iframe[offset] & 0xFF;
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bus->rcvalue[c] = hival + loval;
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}
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return true;
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}
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}
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return false;
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}
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int ibus_chcount(ibus_t* bus) {
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return IBUS_CHANNELS;
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}
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int16_t ibus_getch(ibus_t* bus, int num) {
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if (num < IBUS_CHANNELS) {
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return (int16_t)bus->rcvalue[num];
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}
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return WRONG_RCVAL;
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}
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