116 lines
2.3 KiB
C
116 lines
2.3 KiB
C
#include <fonts.h>
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#include <render.h>
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#define MAXCHR (20*10)
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static uint8_t buf[MAXCHR];
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// Local function: Get next nibble.
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int ctr=0; // offset for next nibble
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int hilo=0; // 0= high nibble next, 1=low nibble next
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const uint8_t * data;
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char gnn(){ // Get next nibble
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static int byte;
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int val;
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hilo=1-hilo;
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if(hilo==1){
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byte=data[ctr];
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ctr++;
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val=byte>>4;
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}else{
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val=byte&0x0f;
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};
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return val;
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};
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// Local function: Unpack "long run".
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int upl(int off){
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int retval;
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while((retval=gnn())==0){
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off++;
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};
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while(off-->0){
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retval=retval<<4;
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retval+=gnn();
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};
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return retval;
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};
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uint8_t * pk_decode(const uint8_t * ldata,int * len){
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ctr=0;hilo=0;
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data=ldata;
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int length=*len; // Length of character bytestream
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int height; // Height of character in bytes
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int hoff; // bit position for non-integer heights
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uint8_t * bufptr=buf; // Output buffer for decoded character
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height=(font->u8Height-1)/8+1;
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hoff=font->u8Height%8;
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#define DYN (12) // Decoder parameter: Fixed value for now.
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int repeat=0; // Decoder internal: repeat colum?
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int curbit=0; // Decoder internal: current bit (1 or 0)
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int pos=0; // Decoder internal: current bit position (0..7)
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int nyb; // Decoder internal: current nibble / value
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if(data[ctr]>>4 == 14){ // Char starts with 1-bits.
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gnn();
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curbit=1;
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};
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while(ctr<length){ /* Iterate the whole input stream */
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/* Get next encoded nibble and decode */
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nyb=gnn();
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if(nyb==15){
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repeat++;
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continue;
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}else if(nyb==14){
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nyb=upl(0);
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nyb+=1;
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repeat+=nyb;
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continue;
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}else if(nyb>DYN){
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nyb=(16*(nyb-DYN-1))+gnn()+DYN+1;
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}else if(nyb==0){
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nyb=upl(1);
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nyb+=(16*(13-DYN)+DYN)-16;
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};
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/* Generate & output bits */
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while(nyb-->0){
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if(pos==0) // Clear each byte before we start.
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*bufptr=0;
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if(curbit==1){
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*bufptr|=1<<(7-pos);
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};
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pos++;
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if(((bufptr-buf)%height)==(height-1) && (pos==hoff)){
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// Finish incomplete last byte per column
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pos=8;
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};
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if(pos==8){
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bufptr++;
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if((bufptr-buf)%height==0){ // End of column?
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while(repeat>0){
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for(int y=0;y<height;y++){
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bufptr[0]=bufptr[-height];
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bufptr++;
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};
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repeat--;
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};
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};
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pos=0;
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};
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};
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curbit=1-curbit;
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};
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*len=(bufptr-buf)/height; // return size of output buffer.
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return buf;
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};
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