CS 2110 Lecture Notes - Lecture 7: Operand, C Dynamic Memory Allocation, Direct Memory Access
3 Dec 2020
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Another pointer syntax to use: you can use this: , the left operand must be a pointer and the right operand must be a struct member. Dma: direct memory access, hardware supported data copy. Up to 10x as fast as array copies. Set up, cpu is halted, data is transferred, and cpu takes back control. Dma channels: skip 0,1,2 channels, only use 3rd channel. Used for general purpose copies: source memory address: reg_dmaxsad (x = 0, 1, 2, 3) location of data that will be copied typically an image or color treated like a 32 bit register, destination memory address: reg_dmaxdad. Almost always just video buffer: controller: how much to copy. On/off, how many elements to copy over, how to iterate through destination, how to iterate over the source. Malloc: getting memory for work, recycling memory when done, os requests for real memory.
