xform: now works with "arbitrary" memory sizes

Signed-off-by: Sean Cross <sean@xobs.io>

memtest/memtest.v

@@ -11,7 +11,7 @@ module memtest (
     input clki
 );
 
-    reg [31:0] mem[0:2047];
+    reg [31:0] mem[0:511];
     reg [10:0] memadr;
     assign random_rom_dat_r = mem[memadr];
 

xform.c

@@ -1,25 +1,10 @@
 #include <stdio.h>
 #include <stdint.h>
 #include <assert.h>
+#include <strings.h>
 
 /*
-bit 0 -> bit 7
+For mem = 65536 bits:
-bit 1 -> bit 15
-bit 8192 -> bit 6
-bit 8193 -> bit 14
-bit 16384 -> bit 5
-bit 16385 -> Bit 13
-bit 24576 -> bit 4
-bit 24577 -> bit 12
-bit 32768 -> bit 3
-bit 32769 -> bit 11
-bit 40960 -> bit 2
-bit 40961 -> bit 10
-bit 49152 -> bit 1
-bit 49153 -> Bit 9
-bit 57344 -> bit 0
-bit 57345 -> bit 8
-
 bit 0 <- 0
 bit 1 <- 8192
 bit 2 <- 16384
@@ -36,6 +21,24 @@ bit 12 <- 40961
 bit 13 <- 1281
 bit 14 <- 49153
 bit 15 <- 57345
+
+For mem = 32768 bits:
+bit 0 <- 0
+bit 1 <- 8192
+bit 2 <- 16384
+bit 3 <- 24576
+bit 4 <- 1
+bit 5 <- 8193
+bit 6 <- 16385
+bit 7 <- 24577
+bit 8 <- 2
+bit 9 <- 8194
+bit 10 <- 16386
+bit 11 <- 24578
+bit 12 <- 3
+bit 13 <- 8195
+bit 14 <- 16387
+bit 15 <- 24579
 */
 
 uint32_t xorshift32(uint32_t x)
@@ -95,16 +98,15 @@ static uint16_t reverse_u16(uint16_t nonreversed)
     return reversed;
 }
 
-static uint32_t get_bit_offset(int bit) {
+static uint32_t get_bit_offset(int x, int total_bits) {
-    return (8192 * (bit & 7)) + (bit >> 3);
+    // return (8192 * (x & 7)) + (x >> 3);
+    int bitshift = ffs(total_bits)-1;
+    return ((x * 8192) % total_bits) + ((x*8192) >> bitshift);
 }
 
 int main(int argc, char **argv)
 {
     int i;
-    for (i = 0; i < 32; i++) {
-        printf("bit offset %d: %d\n", i, get_bit_offset(i));
-    }
     // uint32_t test_1[] = {1};
     // uint32_t test_2[] = {0, 1};
     // uint32_t test_3[] = {2, 0};
@@ -127,23 +129,35 @@ int main(int argc, char **argv)
     //         printf("test_4: bit %d set\n", i);
     // }
 
-    uint32_t input[2048] = {};
+    uint32_t input[512] = {};
-    uint32_t output[2048] = {};
+    uint32_t output[512] = {};
+
+    for (i = 0; i < 32; i++) {
+        printf("bit %d: %d\n", i, get_bit_offset(i, sizeof(input)*8));
+    }
 
     uint32_t init = 1;
     for (i = 0; i < sizeof(input) / 4; i++)
     {
         init = get_rand(init);
         input[i] = init;
+        // input[i] = 0;
     }
+    /*
+    input[0] = 0xf0000000;
+    input[256] = 0xf0000000;
+    input[512] = 0xc0000000;
+    input[768] = 0xc0000000;
+    input[1024] = 0xc0000000;*/
     // print_hex(input, sizeof(input), 0);
     // return;
+    // memset(input, 0xff, sizeof(input));
 
     for (i = 0; i < sizeof(input) * 8; i++)
     {
         int bit;
-        assert(get_bit_offset(i) < sizeof(output) * 8);
+        assert(get_bit_offset(i, sizeof(output)*8) < sizeof(output) * 8);
-        bit = get_bit(input, get_bit_offset(i));
+        bit = get_bit(input, get_bit_offset(i, sizeof(input)*8));
         // bit = get_bit(input, i);
         // if (bit)
         //     printf("bit %d is set\n", i);
@@ -189,7 +203,7 @@ int main(int argc, char **argv)
     //     o16[i] = reverse_u16(o16[i]);
 
     // print_hex(output, sizeof(output), 0);
-    FILE *infile = fopen("infile.txt", "w");
+    FILE *infile = fopen("memtest/mem.init", "w");
     FILE *outfile = fopen("outfile.txt", "w");
     for (i = 0; i < sizeof(input)/4; i++) {
         fprintf(infile, "%08x\n", input[i]);