FallenSigh
52e85aa6fb
dma.h: typedef u32 instead of uint32_t, no stdint.h include dma.c: use u32 instead of uint32_t user-sample.c: unsigned char/int instead of uint8_t/uint32_t Makefile: filter-out -lc -lm -lg -lsemihost from LDFLAGS → picolibc .data section (2.1KB, 532 words) eliminated → startup data-copy loop: ~30000 → ~200 cycles → total start.S latency: ~44000 → ~14000 cycles (~0.42ms at 33MHz)
37 lines
1.1 KiB
C
37 lines
1.1 KiB
C
#include "dma.h"
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void dma_start_transfer(int ch_id, u32 src, u32 dst, u32 bytes, u32 tag) {
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volatile dma_ch_regs_t* ch = DMA_CH(ch_id);
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// 检查通道是否空闲 防止覆盖正在运行的任务
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if (ch->STATUS & STATUS_BUSY_BIT) {
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// printf("channel %d busy\n", ch_id);
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return; // 通道正忙，处理报错或重试
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}
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// 写入基本地址和长度
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ch->SRC_ADDR = src;
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ch->DST_ADDR = dst;
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ch->LENGTH = bytes;
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ch->TAG = tag; // 可选，填入任务ID
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// 置 Burst 属性并触发传输
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// AXI SIZE: 2 (代表 2^2 = 4 Bytes，与 32-bit 数据线匹配)
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// AXI LEN: 15 (代表 16 beats 突发传输，最高效)
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u32 ctrl_val = CTRL_BURST_SIZE(2) | CTRL_BURST_LEN(63);
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// 写入 CTRL 并拉高 Bit 0 (Start)
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ch->CTRL = ctrl_val | CTRL_START_BIT;
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}
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void dma_wait_polling(int ch_id) {
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volatile dma_ch_regs_t* ch = DMA_CH(ch_id);
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// 死等 Done bit 置 1
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while (!(ch->STATUS & STATUS_DONE_BIT)) {
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}
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// 清除 Done 标志位 (Write 1 to Clear Bit 1)
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// 注意：写 1 清 0 的设计，所以我们对 bit 1 写入 1
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ch->STATUS = STATUS_DONE_BIT;
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} |