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Add pseudocode for all instructions.

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This is intended to make the code possible to follow without knowledge
of the ARM instruction set.
This commit is contained in:
Martin Ling
2021-12-21 21:09:45 +00:00
parent 030898315d
commit 59be1fef5a
1 changed files with 45 additions and 45 deletions
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90
firmware/hackrf_usb/sgpio_m0.s
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@ -139,20 +139,20 @@ buf_ptr .req r5
main: // Cycle counts: main: // Cycle counts:
// Initialise registers used for constant values. // Initialise registers used for constant values.
value .req r0 value .req r0
ldr sgpio_int, =SGPIO_EXCHANGE_INTERRUPT_BASE // 2 ldr sgpio_int, =SGPIO_EXCHANGE_INTERRUPT_BASE // sgpio_int = SGPIO_INT_BASE // 2
ldr sgpio_data, =SGPIO_SHADOW_REGISTERS_BASE // 2 ldr sgpio_data, =SGPIO_SHADOW_REGISTERS_BASE // sgpio_data = SGPIO_REG_SS // 2
ldr value, =TARGET_DATA_BUFFER // 2 ldr value, =TARGET_DATA_BUFFER // value = TARGET_DATA_BUFFER // 2
mov buf_base, value // 1 mov buf_base, value // buf_base = value // 1
ldr value, =TARGET_BUFFER_MASK // 2 ldr value, =TARGET_BUFFER_MASK // value = TARGET_DATA_MASK // 2
mov buf_mask, value // 1 mov buf_mask, value // buf_mask = value // 1
ldr value, =STATE_BASE // 2 ldr value, =STATE_BASE // value = STATE_BASE // 2
mov state, value // 1 mov state, value // state = value // 1
// Initialise state. // Initialise state.
zero .req r0 zero .req r0
mov zero, #0 // 1 mov zero, #0 // zero = 0 // 1
str zero, [state, #OFFSET] // 2 str zero, [state, #OFFSET] // state.offset = zero // 2
str zero, [state, #TX] // 2 str zero, [state, #TX] // state.tx = zero // 2
loop: loop:
// The worst case timing is assumed to occur when reading the interrupt // The worst case timing is assumed to occur when reading the interrupt
@ -174,68 +174,68 @@ loop:
// Spin until we're ready to handle an SGPIO packet: // Spin until we're ready to handle an SGPIO packet:
// Grab the exchange interrupt staus... // Grab the exchange interrupt staus...
ldr int_status, [sgpio_int, #INT_STATUS] // 10, twice ldr int_status, [sgpio_int, #INT_STATUS] // int_status = SGPIO_STATUS_1 // 10, twice
// ... check to see if bit #0 (slice A) was set, by shifting it into the carry bit... // ... check to see if bit #0 (slice A) was set, by shifting it into the carry bit...
lsr scratch, int_status, #1 // 1, twice lsr scratch, int_status, #1 // scratch = int_status >> 1 // 1, twice
// ... and if not, jump back to the beginning. // ... and if not, jump back to the beginning.
bcc loop // 3, then 1 bcc loop // if !carry: goto loop // 3, then 1
// Clear the interrupt pending bits that were set. // Clear the interrupt pending bits that were set.
str int_status, [sgpio_int, #INT_CLEAR] // 8 str int_status, [sgpio_int, #INT_CLEAR] // SGPIO_CLR_STATUS_1 = int_status // 8
// ... and grab the address of the buffer segment we want to write to / read from. // ... and grab the address of the buffer segment we want to write to / read from.
ldr buf_ptr, [state, #OFFSET] // buf_ptr = position_in_buffer // 2 ldr buf_ptr, [state, #OFFSET] // buf_ptr = state.offset // 2
add buf_ptr, buf_base // buf_ptr = &buffer + position_in_buffer // 1 add buf_ptr, buf_base // buf_ptr += buf_base // 1
tx .req r0 tx .req r0
// Load direction (TX or RX) // Load direction (TX or RX)
ldr tx, [state, #TX] // 2 ldr tx, [state, #TX] // tx = state.tx // 2
// TX? // TX?
lsr tx, #1 // 1 lsr tx, #1 // tx >>= 1 // 1
bcc direction_rx // 1 thru, 3 taken bcc direction_rx // if !carry: goto direction_rx // 1 thru, 3 taken
direction_tx: direction_tx:
ldm buf_ptr!, {r0-r3} // 5 ldm buf_ptr!, {r0-r3} // r0-r3 = buf_ptr[0:16]; buf_ptr += 16 // 5
str r0, [sgpio_data, #SLICE0] // 8 str r0, [sgpio_data, #SLICE0] // SGPIO_REG_SS[SLICE0] = r0 // 8
str r1, [sgpio_data, #SLICE1] // 8 str r1, [sgpio_data, #SLICE1] // SGPIO_REG_SS[SLICE1] = r1 // 8
str r2, [sgpio_data, #SLICE2] // 8 str r2, [sgpio_data, #SLICE2] // SGPIO_REG_SS[SLICE2] = r2 // 8
str r3, [sgpio_data, #SLICE3] // 8 str r3, [sgpio_data, #SLICE3] // SGPIO_REG_SS[SLICE3] = r3 // 8
ldm buf_ptr!, {r0-r3} // 5 ldm buf_ptr!, {r0-r3} // r0-r3 = buf_ptr[0:16]; buf_ptr += 16 // 5
str r0, [sgpio_data, #SLICE4] // 8 str r0, [sgpio_data, #SLICE4] // SGPIO_REG_SS[SLICE4] = r0 // 8
str r1, [sgpio_data, #SLICE5] // 8 str r1, [sgpio_data, #SLICE5] // SGPIO_REG_SS[SLICE5] = r1 // 8
str r2, [sgpio_data, #SLICE6] // 8 str r2, [sgpio_data, #SLICE6] // SGPIO_REG_SS[SLICE6] = r2 // 8
str r3, [sgpio_data, #SLICE7] // 8 str r3, [sgpio_data, #SLICE7] // SGPIO_REG_SS[SLICE7] = r3 // 8
b done // 3 b done // goto done // 3
direction_rx: direction_rx:
ldr r0, [sgpio_data, #SLICE0] // 10 ldr r0, [sgpio_data, #SLICE0] // r0 = SGPIO_REG_SS[SLICE0] // 10
ldr r1, [sgpio_data, #SLICE1] // 10 ldr r1, [sgpio_data, #SLICE1] // r1 = SGPIO_REG_SS[SLICE1] // 10
ldr r2, [sgpio_data, #SLICE2] // 10 ldr r2, [sgpio_data, #SLICE2] // r2 = SGPIO_REG_SS[SLICE2] // 10
ldr r3, [sgpio_data, #SLICE3] // 10 ldr r3, [sgpio_data, #SLICE3] // r3 = SGPIO_REG_SS[SLICE3] // 10
stm buf_ptr!, {r0-r3} // 5 stm buf_ptr!, {r0-r3} // buf_ptr[0:16] = r0-r3; buf_ptr += 16 // 5
ldr r0, [sgpio_data, #SLICE4] // 10 ldr r0, [sgpio_data, #SLICE4] // r0 = SGPIO_REG_SS[SLICE4] // 10
ldr r1, [sgpio_data, #SLICE5] // 10 ldr r1, [sgpio_data, #SLICE5] // r1 = SGPIO_REG_SS[SLICE5] // 10
ldr r2, [sgpio_data, #SLICE6] // 10 ldr r2, [sgpio_data, #SLICE6] // r2 = SGPIO_REG_SS[SLICE6] // 10
ldr r3, [sgpio_data, #SLICE7] // 10 ldr r3, [sgpio_data, #SLICE7] // r3 = SGPIO_REG_SS[SLICE7] // 10
stm buf_ptr!, {r0-r3} // 5 stm buf_ptr!, {r0-r3} // buf_ptr[0:16] = r0-r3; buf_ptr += 16 // 5
done: done:
offset .req r0 offset .req r0
// Finally, update the buffer location... // Finally, update the buffer location...
mov offset, buf_mask // 1 mov offset, buf_mask // offset = buf_mask // 1
and offset, buf_ptr // offset = (pos_in_buffer + size_copied) % buffer_size // 1 and offset, buf_ptr // offset &= buf_ptr // 1
// ... and store the new position. // ... and store the new position.
str offset, [state, #OFFSET] // 2 str offset, [state, #OFFSET] // state.offset = offset // 2
b loop // 3 b loop // goto loop // 3