mirror of
https://github.com/LNH-team/pico-loader.git
synced 2026-06-02 17:26:48 +02:00
104 lines
2.1 KiB
ArmAsm
104 lines
2.1 KiB
ArmAsm
.cpu arm7tdmi
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.section "dstt_readsd_helper", "ax"
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.syntax unified
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.thumb
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// r0 = src sector
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.global dstt_readSd_applySectorCommand
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.type dstt_readSd_applySectorCommand, %function
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dstt_readSd_applySectorCommand:
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push {r5-r6,lr}
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.global dstt_readSd_sdsc_shift
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dstt_readSd_sdsc_shift:
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lsls r6, r0, #9
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// request sd read for sector 0xaabbccdd
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// 54 aa bb cc dd 00 00 00
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movs r5, #0x54
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strb r5, [r4,#0x8]
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lsrs r5, r6, #24
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strb r5, [r4,#0x9]
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lsrs r5, r6, #16
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strb r5, [r4,#0xA]
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lsrs r5, r6, #8
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strb r5, [r4,#0xB]
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// make sure the last 3 bytes are zero
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movs r5, #0xFF
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ands r6, r5
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str r6, [r4,#0xC] // storing as little-endian puts the bottom 8 bits as first byte
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pop {r5-r6,pc}
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.balign 4
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.global dstt_readSd_waitDataReady
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.type dstt_readSd_waitDataReady, %function
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dstt_readSd_waitDataReady:
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push {r5-r7,lr}
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movs r6, #0x41
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lsls r6, r6, #20 // r6 = 0x04100000
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// sd fifo full poll
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// 80 xx xx xx xx xx xx xx
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// xx bytes are leftover from previous command
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movs r7, #0x80
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strb r7, [r4,#0x8]
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ldr r7, =0xA7180000
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cmd80_poll_loop:
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str r7, [r4,#4]
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cmd80_wait_loop:
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ldrb r5, [r4,#6]
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lsrs r5, r5, #8
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bcc cmd80_wait_loop
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ldr r5, [r6, #0x10]
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cmp r5, #0
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bne cmd80_poll_loop
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pop {r5-r7,pc}
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.balign 4
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// r1 = dst, will be incremented by 512
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.global dstt_readSd_transferData
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.type dstt_readSd_transferData, %function
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dstt_readSd_transferData:
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push {r5-r7,lr}
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ldr r5, =0xA7180000
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movs r6, #0x41
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lsls r6, r6, #20 // r6 = 0x04100000
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// read sd fifo
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// 81 xx xx xx xx xx xx xx
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// xx bytes are leftover from previous command
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movs r5, #0x81
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strb r5, [r4,#0x8]
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movs r5, #0xA1
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strb r5, [r4,#7]
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cmd81_data_loop:
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ldrb r5, [r4,#6]
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lsrs r5, r5, #8 // check if data is ready
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bcc cmd81_data_loop_check_transfer_end // if not skip reading
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ldr r5, [r6, #0x10]
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stmia r1!, {r5}
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cmd81_data_loop_check_transfer_end:
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ldrb r5, [r4,#7]
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lsrs r5, r5, #8 // check if transfer is done
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bcs cmd81_data_loop
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pop {r5-r7,pc}
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.balign 4
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.pool
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.end
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