Get rid of most instance of 'foo == NULL'

core/src/fdrm/crypto/fx_crypt_sha.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "core/include/fdrm/fx_crypt.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ skipping 372 matching lines @@
       ret |= (str[i] - 'a' + 10) & 0xFF;
     } else if (str[i] >= 'A' && str[i] <= 'F') {
       ret |= (str[i] - 'A' + 10) & 0xFF;
     } else {
       FXSYS_assert(FALSE);
     }
   }
   return ret;
 }
 void CRYPT_SHA384Start(void* context) {
-  if (context == NULL) {
+  if (!context) {
     return;
   }
   sha384_context* ctx = (sha384_context*)context;
   FXSYS_memset(ctx, 0, sizeof(sha384_context));
   ctx->state[0] = FX_ato64i("cbbb9d5dc1059ed8");
   ctx->state[1] = FX_ato64i("629a292a367cd507");
   ctx->state[2] = FX_ato64i("9159015a3070dd17");
   ctx->state[3] = FX_ato64i("152fecd8f70e5939");
   ctx->state[4] = FX_ato64i("67332667ffc00b31");
   ctx->state[5] = FX_ato64i("8eb44a8768581511");
@@ skipping 193 matching lines @@
 }
 void CRYPT_SHA384Generate(const uint8_t* data,
                           FX_DWORD size,
                           uint8_t digest[64]) {
   sha384_context context;
   CRYPT_SHA384Start(&context);
   CRYPT_SHA384Update(&context, data, size);
   CRYPT_SHA384Finish(&context, digest);
 }
 void CRYPT_SHA512Start(void* context) {
-  if (context == NULL) {
+  if (!context) {
     return;
   }
   sha384_context* ctx = (sha384_context*)context;
   FXSYS_memset(ctx, 0, sizeof(sha384_context));
   ctx->state[0] = FX_ato64i("6a09e667f3bcc908");
   ctx->state[1] = FX_ato64i("bb67ae8584caa73b");
   ctx->state[2] = FX_ato64i("3c6ef372fe94f82b");
   ctx->state[3] = FX_ato64i("a54ff53a5f1d36f1");
   ctx->state[4] = FX_ato64i("510e527fade682d1");
   ctx->state[5] = FX_ato64i("9b05688c2b3e6c1f");
@@ skipping 30 matching lines @@
                           FX_DWORD size,
                           uint8_t digest[64]) {
   sha384_context context;
   CRYPT_SHA512Start(&context);
   CRYPT_SHA512Update(&context, data, size);
   CRYPT_SHA512Finish(&context, digest);
 }
 #ifdef __cplusplus
 };
 #endif