extmod: Add a2b_base64 and b2a_base64 functions to ubinascii.

1 files changed, 102 insertions, 2 deletions

diff --git a/extmod/modubinascii.c b/extmod/modubinascii.c
index 187c2d3d16..e4ae8c1572 100644
--- a/extmod/modubinascii.c
+++ b/extmod/modubinascii.c
@@ -89,14 +89,114 @@ mp_obj_t mod_binascii_unhexlify(mp_obj_t data) {
 }
 MP_DEFINE_CONST_FUN_OBJ_1(mod_binascii_unhexlify_obj, mod_binascii_unhexlify);
 
+mp_obj_t mod_binascii_a2b_base64(mp_obj_t data) {
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(data, &bufinfo, MP_BUFFER_READ);
+    if (bufinfo.len % 4 != 0) {
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "incorrect padding"));
+    }
+
+    vstr_t vstr;
+    byte *in = bufinfo.buf;
+    if (bufinfo.len == 0) {
+        vstr_init_len(&vstr, 0);
+    }
+    else {
+        vstr_init_len(&vstr, ((bufinfo.len / 4) * 3) - ((in[bufinfo.len-1] == '=') ? ((in[bufinfo.len-2] == '=') ? 2 : 1 ) : 0)); 
+    }
+    byte *out = (byte*)vstr.buf;
+    for (mp_uint_t i = bufinfo.len; i; i -= 4) {
+        char hold[4];
+        for (int j = 4; j--;) {
+            if (in[j] >= 'A' && in[j] <= 'Z') {
+                hold[j] = in[j] - 'A';
+            } else if (in[j] >= 'a' && in[j] <= 'z') {
+                hold[j] = in[j] - 'a' + 26;
+            } else if (in[j] >= '0' && in[j] <= '9') {
+                hold[j] = in[j] - '0' + 52;
+            } else if (in[j] == '+') {
+                hold[j] = 62;
+            } else if (in[j] == '/') {
+                hold[j] = 63;
+            } else if (in[j] == '=') {
+                if (j < 2 || i > 4) {
+                    nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "invalid padding"));
+                }
+                hold[j] = 64;
+            } else {
+                nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "invalid character"));
+            }
+        }
+        in += 4;
+
+        *out++ = (hold[0]) << 2 | (hold[1]) >> 4;
+        if (hold[2] != 64) {
+            *out++ = (hold[1] & 0x0F) << 4 | hold[2] >> 2;
+            if (hold[3] != 64) {
+                *out++ = (hold[2] & 0x03) << 6 | hold[3];
+            }
+        }
+    }
+    return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
+}
+MP_DEFINE_CONST_FUN_OBJ_1(mod_binascii_a2b_base64_obj, mod_binascii_a2b_base64);
+
+mp_obj_t mod_binascii_b2a_base64(mp_obj_t data) {
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(data, &bufinfo, MP_BUFFER_READ);
+
+    vstr_t vstr;
+    vstr_init_len(&vstr, ((bufinfo.len != 0) ? (((bufinfo.len - 1) / 3) + 1) * 4 : 0) + 1);
+    byte *in = bufinfo.buf, *out = (byte*)vstr.buf;
+    for (mp_uint_t i = bufinfo.len; i >= 3; i -= 3) {
+        *out++ = (in[0] & 0xFC) >> 2;
+        *out++ = (in[0] & 0x03) << 4 | (in[1] & 0xF0) >> 4;
+        *out++ = (in[1] & 0x0F) << 2 | (in[2] & 0xC0) >> 6;
+        *out++ = in[2] & 0x3F;
+        in += 3;
+    }
+    if (bufinfo.len % 3 != 0) {
+        *out++ = (in[0] & 0xFC) >> 2;
+        if (bufinfo.len % 3 == 2) {
+            *out++ = (in[0] & 0x03) << 4 | (in[1] & 0xF0) >> 4;
+            *out++ = (in[1] & 0x0F) << 2;
+        }
+        else {
+            *out++ = (in[0] & 0x03) << 4;
+            *out++ = 64;
+        }
+        *out++ = 64;
+    }
+    out = (byte*)vstr.buf;
+    for (mp_uint_t i = vstr.len - 1; i--;) {
+        if (*out < 26) {
+            *out += 'A';
+        } else if (*out < 52) {
+            *out += 'a' - 26;
+        } else if (*out < 62) {
+            *out += '0' - 52;
+        } else if (*out == 62) {
+            *out ='+';
+        } else if (*out == 63) {
+            *out = '/';
+        } else {
+            *out = '=';
+        }
+        out++;
+    }
+    *out = '\n';
+    return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
+}
+MP_DEFINE_CONST_FUN_OBJ_1(mod_binascii_b2a_base64_obj, mod_binascii_b2a_base64);
+
 #if MICROPY_PY_UBINASCII
 
 STATIC const mp_map_elem_t mp_module_binascii_globals_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_ubinascii) },
     { MP_OBJ_NEW_QSTR(MP_QSTR_hexlify), (mp_obj_t)&mod_binascii_hexlify_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_unhexlify), (mp_obj_t)&mod_binascii_unhexlify_obj },
-//    { MP_OBJ_NEW_QSTR(MP_QSTR_a2b_base64), (mp_obj_t)&mod_binascii_a2b_base64_obj },
-//    { MP_OBJ_NEW_QSTR(MP_QSTR_b2a_base64), (mp_obj_t)&mod_binascii_b2a_base64_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_a2b_base64), (mp_obj_t)&mod_binascii_a2b_base64_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_b2a_base64), (mp_obj_t)&mod_binascii_b2a_base64_obj },
 };
 
 STATIC MP_DEFINE_CONST_DICT(mp_module_binascii_globals, mp_module_binascii_globals_table);