86 lines
2.1 KiB
C
86 lines
2.1 KiB
C
#include <stdio.h>
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#include <alloca.h>
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#include <stdlib.h>
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#include <string.h>
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#include <rom/crc.h>
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#include "crc16-ccitt.h"
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#include "mipi.h"
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//Reminder; MIPI is very LSB-first.
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typedef struct {
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uint8_t sot; //should be 0xB8
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uint8_t datatype;
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uint16_t wordcount;
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uint8_t ecc; //0
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uint8_t data[];
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//Footer is 2 bytes of checksum.
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} __attribute__((packed)) DsiLPHdr;
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typedef struct {
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uint8_t sot; //should be 0xB8
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uint8_t datatype;
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uint8_t data[];
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//Footer is 1 byte of ECC
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} __attribute__((packed)) DsiSPHdr;
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// calc XOR parity bit of all '1's in 24 bit value
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static char parity (uint32_t val) {
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uint32_t i,p;
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p=0;
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for(i=0; i!=24; i++) {
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p^=val;
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val>>=1;
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}
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return (p&1);
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}
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static uint8_t calc_ecc(uint8_t *buf) {
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int ret=0;
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uint32_t cmd=(buf[0])+(buf[1]<<8)+(buf[2]<<16);
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if(parity(cmd & 0b111100010010110010110111)) ret|=0x01;
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if(parity(cmd & 0b111100100101010101011011)) ret|=0x02;
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if(parity(cmd & 0b011101001001101001101101)) ret|=0x04;
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if(parity(cmd & 0b101110001110001110001110)) ret|=0x08;
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if(parity(cmd & 0b110111110000001111110000)) ret|=0x10;
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if(parity(cmd & 0b111011111111110000000000)) ret|=0x20;
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return ret;
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}
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static uint16_t mipiword(uint16_t val) {
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uint16_t ret;
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uint8_t *pret=(uint8_t*)&ret;
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pret[0]=(val&0xff);
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pret[1]=(val>>8);
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return ret;
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}
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//Warning: CRC isn't tested (my display does not use it)
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void mipiDsiSendLong(int type, uint8_t *data, int len) {
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DsiLPHdr p;
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uint8_t footer[3];
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uint8_t *datas[3]={(uint8_t*)&p, data, footer};
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int lengths[3]={sizeof(DsiLPHdr), len, sizeof(footer)};
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p.sot=0xB8;
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p.datatype=type;
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p.wordcount=mipiword(len);
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p.ecc=calc_ecc((uint8_t*)&p.datatype);
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int crc=crc16_ccitt(0xFFFF, data, len);
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footer[0]=(crc&0xff);
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footer[1]=(crc>>8);
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footer[2]=(crc&0x8000)?0:0xff; //need one last level transition at end
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mipiSendMultiple(datas, lengths, 3);
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}
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void mipiDsiSendShort(int type, uint8_t *data, int len) {
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DsiSPHdr *p=alloca(sizeof(DsiSPHdr)+2+len);
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p->sot=0xB8;
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p->datatype=type;
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memcpy(p->data, data, len);
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p->data[len]=calc_ecc((uint8_t*)&p->datatype);
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p->data[len+1]=(p->data[len]&0x80)?0:0xff; //need one last level transition at end
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mipiSend((uint8_t*)p, sizeof(DsiSPHdr)+2+len);
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}
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