diff --git a/A5_1.c b/A5_1.c
index 6e64078..ff1bb96 100644
--- a/A5_1.c
+++ b/A5_1.c
@@ -9,32 +9,104 @@
  */
  
 #include <stdint.h>
+#include <string.h>
 #include "A5_1.h"
+#include <avr/pgmspace.h>
+
+uint8_t a5_1_clock_core(a5_1_ctx_t *c, uint8_t clockoverride);
+
 
 /*
  * length is length of key in bytes!
  */
-#define BYTEn(p,s) (*(((uint8_t*)&(p))+s))
 
-void		a5_1_init(a5_1_ctx_t *c, uint8_t *key, uint8_t length);
-
-bool	 a5_1_clock(a5_1_ctx_t *c){
-	bool x1,x2,x3, maj;
-	x1 = PARITY_LOOKUP & (1<< ((BYTEn(c->r1,2)+BYTEn(c->r1,1)>>5) & 0x7);
-	x2 = PARITY_LOOKUP & (1<< (BYTEn(c->r2,2)>>4));
-	x3 = PARITY_LLOKUP & (1<< ((BYTEn(c->r3,2)>>4+BYTEn(c->r3,0)>>7) & 0x7));
-	maj = (((c->r1 & (1<<R1_CLK))?1:0)+((c->r2 & (1<<R2_CLK))?1:0)+((c->r3 & (1<<R3_CLK))?1:0))>=2;
-	if (((c->r1 & (1<<R1_CLK))>>R1_CLK) == maj)
-		c->r1 = c->r1<<1 + x1;
-	if (((c->r2 & (1<<R2_CLK))>>R2_CLK) == maj)
-		c->r2 = c->r2<<1 + x2;
-	if (((c->r3 & (1<<R3_CLK))>>R3_CLK) == maj)
-		c->r3 = c->r3<<1 + x3;
-		
-	return ((c->r1)>>(R1_LENGTH-1)+(c->r2)>>(R2_LENGTH-1)+(c->r3)>>(R3_LENGTH-1))&0x1;
+void a5_1_init(a5_1_ctx_t *c, void* key, uint8_t keylength_b, void* iv, uint8_t ivlength_b){
+	uint8_t i,t;
+	memset(c->r1, 0, 3);
+	memset(c->r2, 0, 3);
+	memset(c->r3, 0, 3);
+	for(i=0; i<keylength_b; ++i){
+		t=((uint8_t*)key)[i/8];
+		t=1&(t>>i);
+		c->r1[0] ^= t;
+		c->r2[0] ^= t;
+		c->r3[0] ^= t;
+		a5_1_clock_core(c, 0x7);
+	}
+	for(i=0; i<ivlength_b; ++i){
+		t=((uint8_t*)iv)[i/8];
+		t=1&(t>>i);
+		c->r1[0] ^= t;
+		c->r2[0] ^= t;
+		c->r3[0] ^= t;
+		a5_1_clock_core(c, 0x7);
+	}
+	for(i=0; i<100; ++i)
+		a5_1_clock_core(c,0);
 }
 
-uint8_t a5_1_gen(a5_	1_ctx_t *c){
+static
+void shiftreg(uint8_t* d){
+	uint8_t c, c2;
+	c=d[0]>>7;
+	d[0] <<= 1;
+	c2=d[1]>>7;
+	d[1] = (d[1]<<1) | c;
+	d[2] = (d[2]<<1) | c2;
+} 
+
+	uint8_t parity3_lut[] PROGMEM = {0, 1, 1, 0,
+		                             1, 0, 0, 1}; 	
+	uint8_t clock_lut[] PROGMEM =  {0x7, 0x6, 0x5, 0x3,
+		                            0x3, 0x5, 0x6, 0x7}; 
+		                            
+uint8_t a5_1_clock_core(a5_1_ctx_t *c, uint8_t clockoverride){
+	uint8_t ret,clk,fb;
+	ret = (0x04&c->r1[2]) | (0x20&c->r2[2]) | (0x40&c->r3[2]);
+	ret = ret^(ret>>6);
+	ret &= 0x7;
+	ret = pgm_read_byte(parity3_lut+ret);
+	clk = (0x08&c->r1[1]) | (0x10&c->r2[1]) | (0x20&c->r3[1]);
+	clk >>= 3;
+	clk = pgm_read_byte(clock_lut+clk);
+	clk |= clockoverride;
+	
+	if(clk&1){
+		fb = c->r1[2] ^ (1&((c->r1[1])>>5));
+		fb &= 0x7;
+		fb = pgm_read_byte(parity3_lut+fb);
+		shiftreg(c->r1);
+		c->r1[0] |= fb;
+		c->r1[2] &= 0x07;
+	}
+	clk>>=1;
+	if(clk&1){
+		fb = c->r2[2]>>4 ;
+		fb &= 0x7;
+		fb = pgm_read_byte(parity3_lut+fb);
+		shiftreg(c->r2);
+		c->r2[0] |= fb;
+		c->r2[2] &= 0x3F;
+	
+	}
+	clk>>=1;
+	if(clk&1){
+		fb = (c->r3[2]>>4) ^ (1&((c->r3[0])>>7));
+		fb &= 0x7;
+		fb = pgm_read_byte(parity3_lut+fb);
+		shiftreg(c->r3);
+		c->r3[0] |= fb;
+		c->r3[2] &= 0x7F;
+	}
+	return ret;
+}
+
+uint8_t a5_1_clock(a5_1_ctx_t *c){
+	return a5_1_clock_core(c, 0);
+}
+
+
+uint8_t a5_1_gen(a5_1_ctx_t *c){
 	uint8_t ret=0;
 	ret = a5_1_clock(c);
 	ret <<= 1;
diff --git a/A5_1.h b/A5_1.h
index 8803198..a6f963a 100644
--- a/A5_1.h
+++ b/A5_1.h
@@ -35,12 +35,13 @@
 #define PARITY_LOOKUP 0x96
 
 typedef struct {
-	uint32_t r1,r2,r3; /* the three regs, 19,22,23 bit in length  */
+	/* we are wasting one byte here but this allows a much faster implementation */
+	uint8_t r1[3], r2[3], r3[3]; /* the three regs, 19,22,23 bit in length  */
 } a5_1_ctx_t;
  
 
-void		a5_1_init(a5_1_ctx_t *c, uint8_t *key, uint8_t length);
-bool		a5_1_clock(a5_1_ctx_t *c);
-uint8_t a5_1_gen(a5_	1_ctx_t *c);
+void		a5_1_init(a5_1_ctx_t *c, void* key, uint8_t keylength_b, void* iv, uint8_t ivlength_b);
+uint8_t		a5_1_clock(a5_1_ctx_t *c);
+uint8_t 	a5_1_gen(a5_1_ctx_t *c);
 
 #endif