mirror of
https://github.com/LNH-team/pico-loader.git
synced 2026-06-02 17:26:48 +02:00
67 lines
1.3 KiB
ArmAsm
67 lines
1.3 KiB
ArmAsm
.cpu arm7tdmi
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.section "ezp_readsddata", "ax"
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.syntax unified
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.thumb
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// r0 = src sector
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// r1 = dst
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// r2 = sector count
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// r3 = sector count for single read
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.global ezp_readSdData
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.type ezp_readSdData, %function
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ezp_readSdData:
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push {r4-r7,lr}
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ldr r4, =0x040001A0
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// Setup command for data read
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// BA 00 00 00 00 00 00 00
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movs r7, #0xBA
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str r7, [r4,#0x8]
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movs r7, #0
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str r7, [r4,#0xC]
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// Set up MCCNT for required read size
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adr r6, readLengthControlValues
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lsls r7, r3, #2
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ldr r5, [r6,r7]
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str r5, [r4,#4]
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ldr r6, =0x04100010
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// Get number of words to read
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// 1 sector == 128 words
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lsls r3, r3, #7
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BA_data_loop:
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ldrb r7, [r4,#6]
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lsrs r7, r7, #8 // check if data is ready
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bcc BA_data_loop_check_transfer_end // if not skip reading
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ldr r7, [r6]
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// Check if the read word needs to be stored.
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cmp r3, #0
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// If we already read all the needed words, skip
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beq BA_data_loop_check_transfer_end
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subs r3, r3, #1
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stmia r1!, {r7}
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BA_data_loop_check_transfer_end:
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ldrb r7, [r4,#7]
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lsrs r7, r7, #8 // check if transfer is done
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bcs BA_data_loop
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pop {r4-r7,pc}
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.balign 4
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readLengthControlValues:
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.word 0
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.word 0xA15A6000
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.word 0xA25A6000
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.word 0xA35A6000
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.word 0xA35A6000
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.pool
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.end
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