mirror of
https://github.com/mmorearty/hardware-breakpoints
synced 2026-06-08 16:06:04 +00:00
Mike Morearty
87 lines
2.0 KiB
C++
87 lines
2.0 KiB
C++
// Copyright (c) 2000 Mike Morearty <mike@morearty.com>
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// Original source and docs: http://www.morearty.com/code/breakpoint
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#include <windows.h>
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#include <assert.h>
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#include "hardwarebp.h"
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#ifdef _DEBUG
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void HardwareBreakpoint::Set(void* address, int len, Condition when)
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{
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// make sure this breakpoint isn't already set
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assert(m_index == -1);
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CONTEXT cxt;
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HANDLE thisThread = GetCurrentThread();
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switch (len)
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{
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case 1: len = 0; break;
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case 2: len = 1; break;
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case 4: len = 3; break;
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default: assert(false); // invalid length
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}
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// The only registers we care about are the debug registers
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cxt.ContextFlags = CONTEXT_DEBUG_REGISTERS;
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// Read the register values
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if (!GetThreadContext(thisThread, &cxt))
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assert(false);
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// Find an available hardware register
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for (m_index = 0; m_index < 4; ++m_index)
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{
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if ((cxt.Dr7 & (1 << (m_index*2))) == 0)
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break;
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}
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assert(m_index < 4); // All hardware breakpoint registers are already being used
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switch (m_index)
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{
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case 0: cxt.Dr0 = (DWORD) address; break;
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case 1: cxt.Dr1 = (DWORD) address; break;
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case 2: cxt.Dr2 = (DWORD) address; break;
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case 3: cxt.Dr3 = (DWORD) address; break;
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default: assert(false); // m_index has bogus value
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}
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SetBits(cxt.Dr7, 16 + (m_index*4), 2, when);
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SetBits(cxt.Dr7, 18 + (m_index*4), 2, len);
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SetBits(cxt.Dr7, m_index*2, 1, 1);
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// Write out the new debug registers
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if (!SetThreadContext(thisThread, &cxt))
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assert(false);
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}
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void HardwareBreakpoint::Clear()
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{
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if (m_index != -1)
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{
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CONTEXT cxt;
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HANDLE thisThread = GetCurrentThread();
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// The only registers we care about are the debug registers
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cxt.ContextFlags = CONTEXT_DEBUG_REGISTERS;
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// Read the register values
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if (!GetThreadContext(thisThread, &cxt))
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assert(false);
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// Zero out the debug register settings for this breakpoint
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assert(m_index >= 0 && m_index < 4); // m_index has bogus value
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SetBits(cxt.Dr7, m_index*2, 1, 0);
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// Write out the new debug registers
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if (!SetThreadContext(thisThread, &cxt))
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assert(false);
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m_index = -1;
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}
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}
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#endif // _DEBUG
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