Implement simple transmit power boost and override

with underflow protection. Making this go all the way to iw or iwconfig is way outsidet of my capabilities but if you want to give it a try, go ahead. Right now this is enough for my needs.

hal/rtl8192e/rtl8192e_phycfg.c

@@ -13,18 +13,34 @@
  *
  *****************************************************************************/
 #define _RTL8192E_PHYCFG_C_
-
-/* #include <drv_types.h> */
-
 #include <rtl8192e_hal.h>
 
-/*---------------------Define local function prototype-----------------------*/
-
-/*----------------------------Function Body----------------------------------*/
-
-/*
- * 1. BB register R/W API
- * */
+/* Manual Transmit Power Control 
+ The following options take values from 0 to 63, where:
+ 0 - disable
+ 1 - lowest transmit power the device can do
+ 2 - highest transmit power the device can do
+ Note that these options may override your country's regulations about transmit power.
+ Setting the device to work at higher transmit powers most of the time may cause premature 
+ failure or damage by overheating. Make sure the device has enough airflow before you increase this.
+ It is currently unknown what these values translate to in dBm.
+*/
+
+// Transmit Power Boost
+// This value is added to the device's calculation of transmit power index.
+// Useful if you want to keep power usage low while still boosting/decreasing transmit power.
+// Can take a negative value as well to reduce power.
+// Zero disables it. Default: 2, for a tiny boost.
+int transmit_power_boost = 2;
+// (ADVANCED) To know what transmit powers this device decides to use dynamically, see:
+// https://github.com/lwfinger/rtl8192ee/blob/42ad92dcc71cb15a62f8c39e50debe3a28566b5f/hal/phydm/rtl8192e/halhwimg8192e_rf.c#L1310
+
+// Transmit Power Override
+// This value completely overrides the driver's calculations and uses only one value for all transmissions.
+// Zero disables it. Default: 0
+int transmit_power_override = 0;
+
+/* Manual Transmit Power Control */
 
 u32
 PHY_QueryBBReg8192E(
@@ -462,6 +478,7 @@ PHY_GetTxPowerLevel8192E(
 )
 {
 #if 0
+ // Doesn't do anything.
  HAL_DATA_TYPE *pHalData = GET_HAL_DATA(Adapter);
  PMGNT_INFO pMgntInfo = &(Adapter->MgntInfo);
  s4Byte TxPwrDbm = 13;
@@ -752,8 +769,12 @@ PHY_GetTxPowerIndex_8192E(
  }
 
  by_rate_diff = by_rate_diff > limit ? limit : by_rate_diff;
- power_idx = base_idx + by_rate_diff + tpt_offset + extra_bias;
-
+ power_idx = base_idx + by_rate_diff + tpt_offset + extra_bias + transmit_power_boost;
+
+ if (transmit_power_override != 0)
+ power_idx = transmit_power_override;
+ if (power_idx < 1)
+ power_idx = 1;
  if (power_idx > MAX_POWER_INDEX)
  power_idx = MAX_POWER_INDEX;