X-Git-Url: https://plomlompom.com/repos/?a=blobdiff_plain;f=src%2Freadwrite.c;h=96505adf4387cc52f4a83241f03098869b0a67d9;hb=0e6c855b67e0cd3def7196396f3d1f45ff85b692;hp=34ec09beecb86d8ee1e06624163143ca8b71e617;hpb=47d7b87570ce3c79d3e0a6b8e765c74d065b6ba5;p=plomrogue

diff --git a/src/readwrite.c b/src/readwrite.c
index 34ec09b..96505ad 100644
--- a/src/readwrite.c
+++ b/src/readwrite.c
@@ -1,38 +1,158 @@
+/* readwrite.c */
+
 #include "readwrite.h"
-#include <stdio.h>
-#include <stdint.h>
-#include <limits.h>
-
-static const uint16_t uchar_s = UCHAR_MAX + 1;
-
-extern uint16_t read_uint16_bigendian(FILE * file) {
-// Read uint16 from file in big-endian order.
-  unsigned char a = fgetc(file);
-  unsigned char b = fgetc(file);
-  return (a * uchar_s) + b; }
-
-extern void write_uint16_bigendian(uint16_t x, FILE * file) {
-// Write uint16 to file in beg-endian order.
-  unsigned char a = x / uchar_s;
-  unsigned char b = x % uchar_s;
-  fputc(a, file);
-  fputc(b, file); }
-
-extern uint32_t read_uint32_bigendian(FILE * file) {
-// Read uint32 from file in big-endian order.
-  unsigned char a = fgetc(file);
-  unsigned char b = fgetc(file);
-  unsigned char c = fgetc(file);
-  unsigned char d = fgetc(file);
-  return (a * uchar_s * uchar_s * uchar_s) + (b * uchar_s * uchar_s) + (c * uchar_s) + d; }
-
-extern void write_uint32_bigendian(uint32_t x, FILE * file) {
-// Write uint32 to file in beg-endian order.
-  unsigned char a = x / (uchar_s * uchar_s * uchar_s);
-  unsigned char b = (x - (a * uchar_s * uchar_s * uchar_s)) / (uchar_s * uchar_s);
-  unsigned char c = (x - ((a * uchar_s * uchar_s * uchar_s) + (b * uchar_s * uchar_s))) / uchar_s;
-  unsigned char d = x % uchar_s;
-  fputc(a, file);
-  fputc(b, file);
-  fputc(c, file);
-  fputc(d, file); }
+#include <stdio.h> /* for FILE typedef, fgetc(), fputc(), fseek() */
+#include <stdint.h> /* for uint8_t, uint16_t, uint32_t */
+
+
+
+/* Read/write "x" from/to "file" as bigendian representation of "size" bits. On
+ * failure, return 1, else 0. (As of of now, all extern read/write functions
+ * build on top of these.)
+ *
+ * Only use multiples of 8 greater or equal 32 for "size", so that storage
+ * inside uint32_t is possible. Originally a bit number check prefaced the code
+ * of both functions. It was removed as redundant due to all possible "size"
+ * values being hardcoded into the library (i.e. in all extern functions calling
+ * / wrapping around either function). If this ever changes, (re-)insert:
+ *
+ *    if (0 == size || size > 32 || 0 != size % 8)
+ *    {
+ *        return 1;
+ *    }
+ */
+static uint8_t read_uintX_bigendian(FILE * file, uint32_t * x, uint8_t size);
+static uint8_t write_uintX_bigendian(FILE * file, uint32_t x, uint8_t size);
+
+
+
+extern uint8_t textfile_sizes(FILE * file, uint16_t * linemax_p,
+                              uint16_t * n_lines_p)
+{
+    int c = 0;
+    uint16_t c_count = 0;
+    uint16_t n_lines = 0;
+    uint16_t linemax = 0;
+    while (1)
+    {
+        c = fgetc(file);
+        if (EOF == c)
+        {
+            break;
+        }
+        c_count++;
+        if ('\n' == c)
+        {
+            if (c_count > linemax)
+            {
+                linemax = c_count;
+            }
+            c_count = 0;
+            if (n_lines_p)
+            {
+                n_lines++;
+            }
+        }
+    }
+    if (0 == linemax && 0 < c_count) /* Handle files that consist of only one */
+    {                                /* line / lack newline chars.            */
+        linemax = c_count;
+    }
+
+    if (-1 == fseek(file, 0, SEEK_SET))
+    {
+        return 1;
+    }
+    * linemax_p = linemax;
+    if (n_lines_p)
+    {
+        * n_lines_p = n_lines;
+    }
+    return 0;
+}
+
+
+
+static uint8_t read_uintX_bigendian(FILE * file, uint32_t * x, uint8_t size)
+{
+    * x = 0;
+    int16_t bitshift = size - 8;
+    int test;
+    for (; bitshift >= 0; bitshift = bitshift - 8)
+    {
+        test = fgetc(file);
+        if (EOF == test)
+        {
+            return 1;
+        }
+        * x = * x + ((uint32_t) test << bitshift);
+    }
+    return 0;
+}
+
+
+
+static uint8_t write_uintX_bigendian(FILE * file, uint32_t x, uint8_t size)
+{
+    int16_t bitshift = size - 8;
+    for (; bitshift >= 0; bitshift = bitshift - 8)
+    {
+        if (EOF == fputc((x >> bitshift) & 0xFF, file))
+        {
+            return 1;
+        }
+    }
+    return 0;
+}
+
+
+
+extern uint8_t read_uint8(FILE * file, uint8_t * x)
+{
+    /* Since read_uintX_bigendian() works on -- and zeroes -- four bytes, direct
+     * work on values of fewer bytes would corrupt immediate neighbor values.
+     */
+    uint32_t y = * x;
+    uint8_t err = read_uintX_bigendian(file, &y, 8);
+    * x = (uint8_t) y;
+    return err;
+}
+
+
+
+extern uint8_t read_uint16_bigendian(FILE * file, uint16_t * x)
+{
+    /* See read_uint8() introductory code comment for rationale. */
+    uint32_t y = * x;
+    uint8_t err = read_uintX_bigendian(file, &y, 16);
+    * x = (uint16_t) y;
+    return err;
+}
+
+
+
+extern uint8_t read_uint32_bigendian(FILE * file, uint32_t * x)
+{
+    return read_uintX_bigendian(file, x, 32);
+}
+
+
+
+extern uint8_t write_uint8(uint8_t x, FILE * file)
+{
+    return write_uintX_bigendian(file, x, 8);
+}
+
+
+
+extern uint8_t write_uint16_bigendian(uint16_t x, FILE * file)
+{
+    return write_uintX_bigendian(file, x, 16);
+}
+
+
+
+extern uint8_t write_uint32_bigendian(uint32_t x, FILE * file)
+{
+    return write_uintX_bigendian(file, x, 32);
+}