Changed callbacks to take user-provided context directly

This is a style change to make littlefs's callbacks consistent with most
callback declarations found in C. That is, taking in a user-provided
`void*`.

Previously, these callbacks took a pointer to the config struct itself,
which indirectly contained a user provided context, and this gets the
job done, but taking in a callback with a `void*` is arguably more
expected, has a better chance of integrating with C++/OS-specific code,
and is more likely to be optimized out by a clever compiler.

---

As a part of these changes, the geometry for the test bds needed to be
moved into bd specific configuration objects. This is a good change as
it also allows for testing situations where littlefs's geometry does not
match the underlying bd.

scripts/test.py

@@ -34,13 +34,43 @@ $(foreach target,$(SRC),$(eval $(FLATTEN)))
 %.test: %.test.o $(foreach f,$(subst /,.,$(SRC:.c=.o)),%.$f)
     $(CC) $(CFLAGS) $^ $(LFLAGS) -o $@
 """
-GLOBALS = """
+BEFORE_MAIN = """
+const char *lfs_testbd_path;
+uint32_t lfs_testbd_cycles;
+
+int lfs_testbd_readctx(void *ctx, lfs_block_t block,
+        lfs_off_t off, void *buffer, lfs_size_t size) {
+    return lfs_testbd_read((lfs_testbd_t*)ctx, block, off, buffer, size);
+}
+
+int lfs_testbd_progctx(void *ctx, lfs_block_t block,
+        lfs_off_t off, const void *buffer, lfs_size_t size) {
+    return lfs_testbd_prog((lfs_testbd_t*)ctx, block, off, buffer, size);
+}
+
+int lfs_testbd_erasectx(void *ctx, lfs_block_t block) {
+    return lfs_testbd_erase((lfs_testbd_t*)ctx, block);
+}
+
+int lfs_testbd_syncctx(void *ctx) {
+    return lfs_testbd_sync((lfs_testbd_t*)ctx);
+}
+"""
+BEFORE_TESTS = """
 //////////////// AUTOGENERATED TEST ////////////////
 #include "lfs.h"
 #include "bd/lfs_testbd.h"
 #include <stdio.h>
+
 extern const char *lfs_testbd_path;
 extern uint32_t lfs_testbd_cycles;
+
+extern int lfs_testbd_readctx(void *ctx, lfs_block_t block,
+        lfs_off_t off, void *buffer, lfs_size_t size);
+extern int lfs_testbd_progctx(void *ctx, lfs_block_t block,
+        lfs_off_t off, const void *buffer, lfs_size_t size);
+extern int lfs_testbd_erasectx(void *ctx, lfs_block_t block);
+extern int lfs_testbd_syncctx(void *ctx);
 """
 DEFINES = {
     'LFS_READ_SIZE': 16,
@@ -67,11 +97,11 @@ PROLOGUE = """
     __attribute__((unused)) int err;
     
     __attribute__((unused)) const struct lfs_cfg cfg = {
-        .context        = &bd,
-        .read           = lfs_testbd_read,
-        .prog           = lfs_testbd_prog,
-        .erase          = lfs_testbd_erase,
-        .sync           = lfs_testbd_sync,
+        .ctx            = &bd,
+        .read           = lfs_testbd_readctx,
+        .prog           = lfs_testbd_progctx,
+        .erase          = lfs_testbd_erasectx,
+        .sync           = lfs_testbd_syncctx,
         .read_size      = LFS_READ_SIZE,
         .prog_size      = LFS_PROG_SIZE,
         .block_size     = LFS_BLOCK_SIZE,
@@ -82,17 +112,21 @@ PROLOGUE = """
     };
 
     __attribute__((unused)) const struct lfs_testbd_cfg bdcfg = {
+        .read_size          = LFS_READ_SIZE,
+        .prog_size          = LFS_PROG_SIZE,
+        .erase_size         = LFS_BLOCK_SIZE,
+        .erase_count        = LFS_BLOCK_COUNT,
         .erase_value        = LFS_ERASE_VALUE,
         .erase_cycles       = LFS_ERASE_CYCLES,
         .badblock_behavior  = LFS_BADBLOCK_BEHAVIOR,
         .power_cycles       = lfs_testbd_cycles,
     };
 
-    lfs_testbd_createcfg(&cfg, lfs_testbd_path, &bdcfg) => 0;
+    lfs_testbd_createcfg(&bd, lfs_testbd_path, &bdcfg) => 0;
 """
 EPILOGUE = """
     // epilogue
-    lfs_testbd_destroy(&cfg) => 0;
+    lfs_testbd_destroy(&bd) => 0;
 """
 PASS = '\033[32m✓\033[0m'
 FAIL = '\033[31m✗\033[0m'
@@ -468,7 +502,7 @@ class TestSuite:
     def build(self, **args):
         # build test files
         tf = open(self.path + '.test.c.t', 'w')
-        tf.write(GLOBALS)
+        tf.write(BEFORE_TESTS)
         if self.code is not None:
             tf.write('#line %d "%s"\n' % (self.code_lineno, self.path))
             tf.write(self.code)
@@ -483,14 +517,13 @@ class TestSuite:
                     for line in f:
                         tfs[case.in_].write(line)
                 tfs[case.in_].write('\n')
-                tfs[case.in_].write(GLOBALS)
+                tfs[case.in_].write(BEFORE_TESTS)
 
             tfs[case.in_].write('\n')
             case.build(tfs[case.in_], **args)
 
+        tf.write(BEFORE_MAIN)
         tf.write('\n')
-        tf.write('const char *lfs_testbd_path;\n')
-        tf.write('uint32_t lfs_testbd_cycles;\n')
         tf.write('int main(int argc, char **argv) {\n')
         tf.write(4*' '+'int case_         = (argc > 1) ? atoi(argv[1]) : 0;\n')
         tf.write(4*' '+'int perm          = (argc > 2) ? atoi(argv[2]) : 0;\n')