1 files changed, 54 insertions, 6 deletions

diff --git a/src/math/field.c b/src/math/field.c
index a4b038e..4d62c73 100644
--- a/src/math/field.c
+++ b/src/math/field.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2017 J08nY
  */
 #include "field.h"
+#include "io/input.h"
 #include "poly.h"
 #include "random.h"
 
@@ -27,21 +28,68 @@ int field_random(curve_t *curve, config_t *config, ...) {
 			curve->field = field_binaryr(config->bits);
 			return 1;
 		default:
-			return 0; /* NOT REACHABLE */
+			return INT_MIN; /* NOT REACHABLE */
 	}
 }
 
 int field_input(curve_t *curve, config_t *config, ...) {
-	return INT_MIN;  // NOT IMPLEMENTED
+	pari_sp ltop = avma;
+	switch (config->field) {
+		case FIELD_PRIME: {
+			GEN p = fread_prime(in, "p:", config->bits);
+			if (equalii(p, gen_m1)) {
+				avma = ltop;
+				return 0;
+			}
+			curve->field = p;
+			return 1;
+		}
+		case FIELD_BINARY: {
+			GEN e1 = fread_short(in, "e1:");
+			if (equalii(e1, gen_m1)) {
+				avma = ltop;
+				return 0;
+			}
+			GEN e2 = fread_short(in, "e2:");
+			if (equalii(e2, gen_m1)) {
+				avma = ltop;
+				return 0;
+			}
+			GEN e3 = fread_short(in, "e3:");
+			if (equalii(e3, gen_m1)) {
+				avma = ltop;
+				return 0;
+			}
+
+			if (isintzero(e1) && isintzero(e2) && isintzero(e3)) {
+				fprintf(stderr, "At least one exponent must be nonzero.\n");
+				avma = ltop;
+				return 0;
+			}
+
+			GEN v = gtovec0(gen_0, config->bits + 1);
+			gel(v, config->bits + 1) = gen_1;
+			if (gsigne(e1) == 1) gel(v, itos(e1) + 1) = gen_1;
+			if (gsigne(e2) == 1) gel(v, itos(e2) + 1) = gen_1;
+			if (gsigne(e3) == 1) gel(v, itos(e3) + 1) = gen_1;
+			gel(v, 1) = gen_1;
+
+			GEN poly = gmul(gtopolyrev(v, -1), gmodulss(1, 2));
+
+			GEN field = gerepilecopy(ltop, ffgen(poly, -1));
+			curve->field = field;
+			return 1;
+		}
+		default:
+			return INT_MIN; /* NOT REACHABLE */
+	}
 }
 
 GEN field_params(GEN field) {
 	pari_sp ltop = avma;
 
 	if (typ(field) == t_INT) {
-		GEN p3 = cgetg(2, t_VEC);
-		gel(p3, 1) = gcopy(field);
-		return gerepilecopy(ltop, p3);
+		return gtovec(field);
 	}
 
 	GEN out = gtovec0(gen_0, 3);
@@ -50,7 +98,7 @@ GEN field_params(GEN field) {
 	long l2 = glength(member_mod(field)) - 2;
 	{
 		pari_sp btop = avma;
-		for (long i = 0; i <= l2; ++i) {
+		for (long i = l2; i > 0; --i) {
 			GEN c = polcoeff0(member_mod(field), i, -1);
 			if (cmpis(c, 0) != 0) {
 				gel(out, j) = stoi(i);