Added Berry ``bytes().reverse()`` method

CHANGELOG.md

@@ -8,6 +8,7 @@ All notable changes to this project will be documented in this file.
 - Support for Digital Addressable Lighting Interface (DALI) by Andrei Kazmirtsuk (#16938)
 - Support for two phase power calibration using commands ``PowerSet2``, ``VoltageSet2`` and ``CurrentSet2``
 - Support for NTAG2xx tags read and write on PN532 NFC reader (#16939)
+- Added Berry ``bytes().reverse()`` method
 
 ### Breaking Changed
 

lib/libesp32/berry/src/be_byteslib.c

@@ -957,7 +957,6 @@ static int m_setfloat(bvm *vm)
  * `setbytes(index:int, fill:bytes [, from:int, len:int]) -> nil`
  * 
  */
-#include <stdio.h>
 static int m_setbytes(bvm *vm)
 {
     int argc = be_top(vm);
@@ -968,7 +967,7 @@ static int m_setbytes(bvm *vm)
         size_t from_len_total;
         const uint8_t* buf_ptr = (const uint8_t*) be_tobytes(vm, 3, &from_len_total);
         if (idx < 0) { idx = 0; }
-        if ((size_t)idx >= attr.len) { idx = attr.len; }
+        if (idx >= attr.len) { idx = attr.len; }
 
         int32_t from_byte = 0;
         if (argc >= 4 && be_isint(vm, 4)) {
@@ -981,9 +980,9 @@ static int m_setbytes(bvm *vm)
         if (argc >= 5 && be_isint(vm, 5)) {
             from_len = be_toint(vm, 5);
             if (from_len < 0) { from_len = 0; }
-            if (from_len >= from_len_total) { from_len = from_len_total; }
+            if (from_len >= (int32_t)from_len_total) { from_len = from_len_total; }
         }
-        if ((size_t) idx + (size_t)from_len >= attr.len) { from_len = attr.len - idx; }
+        if (idx + from_len >= attr.len) { from_len = attr.len - idx; }
 
         // all parameters ok
         if (from_len > 0) {
@@ -993,6 +992,66 @@ static int m_setbytes(bvm *vm)
     be_return_nil(vm);
 }
 
+
+/*
+ * Reverses in-place a sub-buffer composed of groups of n-bytes packets
+ *
+ * This is useful for pixel manipulation when displaying RGB pixels
+ * 
+ * `reverse([index:int, len:int, grouplen:int]) -> self`
+ * 
+ */
+static int m_reverse(bvm *vm)
+{
+    int argc = be_top(vm);
+    buf_impl attr = bytes_check_data(vm, 0); /* we reserve 4 bytes anyways */
+    check_ptr(vm, &attr);
+
+    int32_t idx = 0;            /* start from index 0 */
+    int32_t len = attr.len;     /* entire len */
+    int32_t grouplen = 1;       /* default to 1-byte group */
+
+    if (argc >= 2 && be_isint(vm, 2)) {
+        idx = be_toint(vm, 2);
+        if (idx < 0) { idx = 0; }               /* railguards */
+        if (idx > attr.len) { idx = attr.len; }
+    }
+    if (argc >= 3 && be_isint(vm, 3)) {
+        len = be_toint(vm, 3);
+        if (len < 0) { len = attr.len - idx; }  /* negative len means */
+    }
+    if (idx + len >= attr.len) { len = attr.len - idx; }
+
+    // truncate len to multiple of grouplen
+    if (argc >= 4 && be_isint(vm, 4)) {
+        grouplen = be_toint(vm, 4);
+        if (grouplen <= 0) { grouplen = 1; }
+    }
+    len = len - (len % grouplen);
+
+    // apply reverse
+    if (len > 0) {
+        if (grouplen == 1) {
+            /* fast version if simple byte inversion */
+            for (int32_t i = idx, j = idx + len -1; i < j; i++, j--) {
+                uint8_t temp = attr.bufptr[i];
+                attr.bufptr[i] = attr.bufptr[j];
+                attr.bufptr[j] = temp;
+            }
+        } else {
+            for (int32_t i = idx, j = idx + len - grouplen; i < j; i += grouplen, j -= grouplen) {
+                for (int32_t k = 0; k < grouplen; k++) {
+                    uint8_t temp = attr.bufptr[i+k];
+                    attr.bufptr[i+k] = attr.bufptr[j+k];
+                    attr.bufptr[j+k] = temp;
+                }
+            }
+        }
+    }
+    be_pushvalue(vm, 1);    /* push bytes object */
+    be_return(vm);
+}
+
 static int m_setitem(bvm *vm)
 {
     int argc = be_top(vm);
@@ -1627,6 +1686,7 @@ void be_load_byteslib(bvm *vm)
         { "size", m_size },
         { "resize", m_resize },
         { "clear", m_clear },
+        { "reverse", m_reverse },
         { "copy", m_copy },
         { "+", m_merge },
         { "..", m_connect },
@@ -1672,6 +1732,7 @@ class be_class_bytes (scope: global, name: bytes) {
     size, func(m_size)
     resize, func(m_resize)
     clear, func(m_clear)
+    reverse, func(m_reverse)
     copy, func(m_copy)
     +, func(m_merge)
     .., func(m_connect)

lib/libesp32/berry/tests/bytes.be

@@ -225,3 +225,26 @@ assert(a == bytes('112233445566CCDD99'))
 a = b.copy()
 a.setbytes(0, a0)
 assert(a == bytes('112233445566'))
+
+# reverse
+assert(bytes().reverse() == bytes())
+assert(bytes("AA").reverse() == bytes("AA"))
+assert(bytes("1122334455").reverse() == bytes("5544332211"))
+assert(bytes("11223344").reverse() == bytes("44332211"))
+
+assert(bytes("0011223344").reverse(1) == bytes("0044332211"))
+assert(bytes("0011223344").reverse(3) == bytes("0011224433"))
+assert(bytes("0011223344").reverse(4) == bytes("0011223344"))
+assert(bytes("0011223344").reverse(5) == bytes("0011223344"))
+assert(bytes("0011223344").reverse(15) == bytes("0011223344"))
+assert(bytes("0011223344").reverse(-2) == bytes("4433221100"))
+
+assert(bytes("0011223344").reverse(1,3) == bytes("0033221144"))
+assert(bytes("0011223344").reverse(1,0) == bytes("0011223344"))
+assert(bytes("0011223344").reverse(2,2) == bytes("0011332244"))
+assert(bytes("0011223344").reverse(0,2) == bytes("1100223344"))
+assert(bytes("0011223344").reverse(nil,2) == bytes("1100223344"))
+assert(bytes("0011223344").reverse(1, nil) == bytes("0044332211"))
+
+assert(bytes("0011223344").reverse(nil, nil, 2) == bytes("2233001144"))
+assert(bytes("001122334455").reverse(nil, nil, 3) == bytes("334455001122"))